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Articles in press, not assigned to volumes/issues, but citable by DOI.

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In press , doi: 10.1007/s10118-019-2191-6
[Abstract](0) [FullText HTML](0) [PDF 994KB](0)
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The low melt strength and poor crystallization behavior severely limits the processing and application of PLA as biodegradable film materials. In this work, three-arm PLLA (3A-PLLA) grafted silica nanoparticles with two kinds of topology structures were introduced into PLA matrix to improve the performance. Different methods were used to characterize the structure of grafted 3A-PLLA chains, grafting density, and the thermal decomposition behavior of the nanoparticles. By varying different mass ratios of raw materials and altering the order of dropping solution in the reaction, high grafting density-tangled 3A-PLLA grafted SiO2 were synthesized in " 3A-PLLA grafting to SiO2” (GTS) while low grafting density-stretched 3A-PLLA grafted SiO2 were obtained in " SiO2 grafting to 3A-PLLA” (GTA). Topology of nanoparticles as well as the filler-matrix interaction is critical important to structure bio-nanocomposites with desirable properties. Thus, the GTS and GTA nanoparticles were introduced into PLA matrix to assess the effect. The SEM photographs showed the uniform dispersion of modified nanoparticles. While the shear rheology results revealed that the GTA nanoparticles made a more significant contribution on the melt-strengthen and relaxation time-extension of PLA. Moreover, it is suggested that the GTA nanoparticles are more effective to act as nucleating agent for PLA, which was certified by DSC and POM researches. All of the above improvements of GTA nanocomposites can be ascribed to the stronger entanglements between 3A-PLLA stretched by nano-SiO2 and PLA matrix.
In press , doi: 10.1007/s10118-019-2171-x
[Abstract](2) [PDF 6827KB](0)
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Two-dimensional (2D) polymers are a class of fascinating polymers as they exhibit unique physical, chemical, mechanical, and electronic properties that are completely different from traditional linear or branched polymers. They are very promising for applications in catalysis, separation, optoelectronics, energy storage, and nanomedicine. Recently, ultrathin 2D conjugated polymers have emerged as advanced materials for converting solar energy into chemical energy. The inherent 2D planar structure with in-plane periodicity offers many features that are highly desirable for photon-involved catalytic energy conversion processes, including high absorption coefficients, large surface areas, abundant surface active sites, and efficient charge separation. Moreover, the possibility of fine tuning the optoelectronic and structural properties through precise molecular engineering have opened up new opportunities for design and synthesis of novel 2D polymer nanosheets with unprecedented applications. Here, we highlight recent advances in developing ultrathin 2D conjugated polymer nanosheets for solar-to-chemical energy conversion. Specifically, we discuss emerging applications of ultrathin 2D conjugated polymer nanosheets for solar-driven water splitting and CO2 reduction. Meanwhile, future challenges and prospects for design and synthesis of ultrathin 2D conjugated polymer nanosheets for solar fuel generation are also included.
In press , doi: 10.1007/s10118-019-2190-7
[Abstract](3) [FullText HTML](3) [PDF 852KB](0)
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Two aromatic co-polyamides were synthesized combining two diacid monomers containing bulky pendant groups, 5-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido) isophthalic acid, DEAIA, and 5-tert-butylisophthalic acid, TERT, with 4,4′-(hexafluoroisopropylidene)dianiline, HFA or 2,3,5,6-tetramethyl-1,4-phenylenediamine, Durene, by direct polycondensation. The obtained aromatic co-polyamides were confirmed by FTIR, Raman and 1H-NMR. The co-copolyamide films, DHTH and DDTD, exhibited rms-roughness values between 0.94 nm and 1.60 nm, respectively; moreover, they presented good thermal stability up to 300 °C. Young’s moduli of the co-polyamide films was between 4.1 and 4.3 GPa. X-ray diffraction results showed that the co-polyamide films are amorphous due the incorporation of both bulky pendant groups, tert-butil and dibenzobarrelene. The combination of bulky pendant groups provide intrinsically transparent co-polyamide films with a higher than 88% transmittance in the 400−780 nm range. Due to these outstanding film and optical properties they are suggested as flexible substrates for solar cell applications and other portable electronics devices.
In press , doi: 10.1007/s10118-019-2192-5
[Abstract](10) [FullText HTML](5) [PDF 2328KB](6)
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To investigate the effect of graphene (Gra) modified by ethoxycarbonyl ionic liquid (IL) on the dispersion of Gra, chain mobility of poly(L-lactic acid) (PLLA) and crystallization kinetics of PLLA, a series of PLLA nanocomposites have been prepared using solution-cast method. IL can improve the dispersion of Gra in PLLA matrix and the samples contained IL have higher growth rate of PLLA spherulite than neat PLLA. PLLA/IL/Gra and PLLA/2Gra have the same relaxation strength and time of the αN relaxation that corresponds to the longest normal mode motion at 110−140 °C. PLLA/IL/Gra has the faster crystallization rate than PLLA/2Gra, which might be attributed to the Gra-imidazolium cation interaction in IL modified Gra, the significant dispersion effect of IL at Gra surface, and the increase of nuclei density of PLLA/IL/Gra.
In press , doi: 10.1007/s10118-019-2173-8
[Abstract](15) [FullText HTML](8) [PDF 1138KB](4)
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The thermal and mechanical properties of the chemically imidized polyimide (CIPI) films and thermally imidized polyimide (TIPI) films were investigated systematically. Experimental results indicated that the CIPI films show dramatically enhanced tensile strength and modulus with obviously reduced coefficient of thermal expansion (CTE) in comparison with TIPI films. These enhancements results from the high in-plane orientation and close packing of the CIPI backbones. Compared with thermal imidization which starts at about 140 °C, the chemical imidization activated by acetic anhydride and isoquinoline initiates the cyclization even at room temperature. The resulting imide rings restrict the mobility of polymer chains and lead to the in-plane orientation as the solvent evaporation. Additionally, fever small molecules remain in the films after treated at 120 °C by chemical imidization than by thermal imidization. The polymer chain plasticization caused by the evaporations of small molecules at high temperature is obviously restricted. Moreover, the partially imidized polymer inhibits the decomposition of mainchains that occurs at subsequent high temperature process, being beneficial to the formation of high molecular weight PI films. Hence, chemical imidization pathway shows apparent advantage to produce PI films with great combined properties, including high modulus, strength and toughness, as well as high thermal dimension stability etc.
In press , doi: 10.1007/s10118-019-2172-9
[Abstract](10) [PDF 630KB](1)
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We present here the development of cholesterol (Chol)-modified dendrimer system for targeted chemotherapy of folate (FA) receptor-expressing cancer cells. In our study, poly(amidoamine) (PAMAM) dendrimers of generation 5 (G5) were functionalized step-by-step with Chol, fluorescein isothiocyanate (FI), and FA via a poly(ethylene glycol) (PEG) spacer (PEG-FA), and then acetamide to shield their remaining surface amines. The synthesized G5.NHAc-Chol-FI-PEG-FA (for short, G5-CFPF) dendrimers were utilized to encapsulate 10-hydroxycamptothecin (HCP), a hydrophobic anticancer drug. We find that each G5-CFPF dendrimer can encapsulate 13.8 HCP molecules. The complexes show a slower release profiles of HCP in a pH-dependent manner than the control complexes formed using the same dendrimers without Chol under the same conditions. Thanks to the targeting role played by FA, the complexes display a specific inhibition efficacy to FA receptor-expressing cervical cancer cells. The designed Chol-modified dendrimers may be adopted as a promising carrier for application in targeted cancer therapy.
In press , doi: 10.1007/s10118-018-2146-3
[Abstract](20) [FullText HTML](10) [PDF 862KB](3)
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In this study, a series of aryloxy-aluminoxanes originated directly from the hydrolysis of reaction products of AlMe3 and phenols were synthesized, which could serve as effective polymer-retarding activators for the iron-catalyzed ethylene oligomerization. The molar ratios of [PhOH]/[AlMe3] and [H2O]/[Al] during the preparation were explored and their impacts on the oligomerization activity and product distribution were discussed. To obtain the effective activators with good polymer-retarding effect and relatively high activity, the optimized conditions were proposed to be [PhOH]/[AlMe3] = 0.5 and [H2O]/[Al] = 0.7. Various aluminoxanes with different [―OH] sources confirmed the importance of using phenols in preparing the effective polymer-retarding activators. By utilizing these aryloxy-aluminoxanes, the mass fraction of polymers in the total products could be reduced to lower than 1.0 wt%, which is much lower than that of the MAO-activated systems (> 30 wt%). This is a potential benefit for the industrial application of the iron-catalyzed oligomerization process.
In press , doi: 10.1007/s10118-018-2153-4
[Abstract](8) [FullText HTML](7) [PDF 595KB](0)
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In our present work, a novel controlled radical polymerization system is developed based on xanthene-9-thione (XT). It was found that the radical polymerization of styrene (St) became controlled in the presence of a small amount of XT. At the early stage of the polymerization, the polymerization rate was relatively low and the as-formed polystyrene (PS) had low number-average molecular weight (Mn) and narrow polydispersity (Ð). After XT was consumed, the polymerization rate increased dramatically and the Mn of PS increased gradually with polymerization proceeding. When the polymerization of St was carried out with a proper molar ratio of initiator to XT and at an appropriate temperature, shortened slow polymerization stage and good control over Mn could be achieved. To further improve the regulating ability of XT, a series of substituent groups (―CF3, ―CH(CH3)2, ―N(CH3)2) were introduced onto the xanthene ring of XT, and the effects of these derivatives on the polymerization of St were investigated in detail. UV-Vis spectroscopy was carried out to monitor the concentration of XT during the polymerization and the chemical structure of the as-formed PS was fully characterized by 1H-NMR and ESI-MS analysis. A possible mechanism involving the formation and evolution of the cross-termination products was proposed to interpret the observed polymerization behavior.
In press , doi: 10.1007/s10118-018-2156-1
[Abstract](11) [FullText HTML](6) [PDF 1175KB](1)
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Bacterial infections and the associated morbidity and mortality due to bacterial pathogens in wounds and medical implants have been increasing as most of current coatings cannot fulfill all the requirements including excellent intrinsically antibacterial activity, low cytotoxicity, and favorable physical properties. Herein, we present a kind of antibacterial hydrogel based on ε-poly(L-lysine) (EPL) grafted carboxymethyl chitosan (CMC-g-EPL) as the inherently antibacterial matrix and the surplus EPL as highly efficient antimicrobial agent. Such hydrogels possess tunable swelling abilities with water absorption percentages of 800%–2000% and modulus varying from 10 kPa to 100 kPa, and exhibit two-stage excellent antibacterial behavior. First, the free EPL can be released from the hydrogel network for quick and highly efficient bacteria killing with 99.99% of efficacy; second, the grafted EPL endows hydrogel matrix with prolonged intrinsically antibacterial activity, especially when most of free EPL is released from the hydrogel. Overall, we provide a new insight for preparing highly effective antibacterial hydrogels.
In press , doi: 10.1007/s10118-018-2157-0
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A series of cross-linked poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/octavinyloctasilasesquioxane (PHBV/OVS) composites were obtained by a simple melt reactive processing technique. Dicumyl peroxide (DCP) and OVS were employed as a free radical initiator and a cross-linking agent, respectively. The chemical structure of these produced composites were identified by 1H/13C/29Si-nuclear magnetic resonance spectroscopy (1H/13C/29Si-NMR) and Fourier transform infrared spectroscopy (FTIR). The melting behavior, non-isothermal crystallization, spherulite morphology and thermal stability property of PHBV/OVS composites were also investigated. The nucleation behaviors and crystallization rate of PHBV/OVS were significantly enhanced with the formation of cross-linked networks with different side-chains and cross-linking points. The red shift of crystalline peak temperature with addition of a small amount of OVS content evidenced the higher crystalline ability compared with the neat PHBV. However there was a threshold content, beyond which the crystallization rate weakened again. Additionally, the cross-linked structure of PHBV/OVS composites could be adjusted by changing the amount of OVS.
In press , doi: 10.1007/s10118-018-2161-4
[Abstract](6) [FullText HTML](7) [PDF 515KB](0)
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We present here the thermodynamic investigation of in situ cascade polycondensation-coupling ring-opening polymerization (PROP) for three cyclic aromatic ester monomers, i.e., cyclic oligo(2-methyl-1,3-propylene terephthalate)s (COMPTs), cyclic oligo(neopentylene terephthalate)s (CONTs) and cyclic oligo(2-methyl-2-propyl-1,3-propylene terephthalate)s (COMPPTs). The equibrium monomer to polymer weight ratio in bulk at different polymerization temperatures for each monomer was estimated by the size exclusion chromatography (SEC), and the thermodynamic parameters were estimated by Dainton equation. Quite different from the thermodynamics of aliphatic lactones polymerization, which is an exothermic process with entropy reduction, our results showed the polymerization thermodynamics for three cyclic aromatic ester monomers was a weak exothermic process with slight entropy increment, i.e., a both enthalpy and entropy driving process. Among them, CONTs showed the largest value of enthalpy change, due to its symmetric dimethyl substitution on β-position of propandiol segments.
In press , doi: 10.1007/s10118-018-2165-0
[Abstract](13) [FullText HTML](6) [PDF 1142KB](1)
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A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-aminopropyl ether) and hexanediamine, m-xylylenediamine, or diethylene glycol bis(3-aminopropyl) ether at 100 °C for 6 h under normal pressure. Melt transurethane polycondensation was successively conducted at 170 °C under a reduced pressure of 399 Pa for different time periods. A series of non-isocyanate thermoplastic polyureas (NI-TPUreas) were prepared. The NI-TPUreas were characterized by gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy, and tensile test. NI-TPUreas exhibited Mn of up to 1.67 × 104 g/mol, initial decomposition temperature over 290 °C, and tensile strength of up to 32 MPa. Several crystallizable NI-TPUreas exhibited Tm exceeding 98 °C. NI-TPUreas with good thermal and mechanical properties were prepared through a green and simple one-pot non-isocyanate route.
In press , doi: 10.1007/s10118-018-2168-x
[Abstract](11) [FullText HTML](7) [PDF 788KB](1)
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In this study we report design of stimuli-responsive coating based on poly(2-methyl-2-oxazoline-random-glycidyl methacrylate) (PMOXA-r-GMA) comb copolymer and poly(acrylic acid)-block-poly(glycidyl methacrylate) (PAA-b-PGMA) block copolymers and scrutinize its ability to control protein adsorption. Firstly, PMOXA/PAA based coatings were prepared by simply spin coating the mixture of PMOXA-r-GMA and PAA-b-PGMA copolymer solutions onto silicon substrates followed by annealing at 110 °C. Then coatings were rigorously characterized by X-ray photoelectron spectroscopy (XPS), the static water contact angle (WCA) test, ellipsometry and atomic force microscopy (AFM). After that, the relationship of switchable behavior of PMOXA/PAA based coatings with PAA content and chain length was investigated through the change of thickness and WCA upon pH and ionic strength (I) trigger, which indicated that the change in thickness and WCA was triggered when PAA contents were increased as well as by increasing chain length of PAA in PMOXA/PAA based coatings. Finally, real-time adsorption/desorption of lysozyme (Lyso) on PMOXA/PAA based coatings was monitored using quartz crystal microbalance with dissipation monitoring (QCM-D). The results showed that the Lyso adsorption amount was increased upon increasing chain length and contents of PAA in PMOXA/PAA based coatings. The adsorbed Lyso was then efficiently desorbed by changing pH and I of medium with the maximum desorption (> 90% desorption percentage) observed for the suitable ratio of PMOXA and PAA while chain length of PAA was kept longer than that of PMOXA. Furthermore, the prepared coatings were found to repeatedly adsorb and desorb Lyso for four successive cycles of adsorption/desorption, which confirmed the stability of prepared coatings.
In press , doi: 10.1007/s10118-018-2154-3
[Abstract](15) [FullText HTML](7) [PDF 704KB](0)
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Light polymeric soundproofing materials (density = 63 kg/m3) of interest for the transportation industry were fabricated through electrospinning. Blankets of electrospun polyvinylpyrrolidone (average fiber diameter = (1.6 ± 0.5) or (2.8 ± 0.5) µm) were obtained by stacking disks of electrospun mats. The sound absorption coefficients were measured using the impedance tube instrument based on ASTM E1050 and ISO 10534-2. For a given set of disks (from a minimum of 6) the sound absorption coefficient changed with the frequency (in the range 200–1600 Hz) following a bell shape curve with a maximum (where the coefficient is greater than 0.9) that shifts to lower frequencies at higher piled disks number and greater fiber diameter. This work showed that electrospinning produced sound absorbers with reduced thickness (2–3 cm) and excellent sound-absorption properties in the low and medium frequency range.
In press , doi: 10.1007/s10118-018-2162-3
[Abstract](14) [FullText HTML](6) [PDF 645KB](0)
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Bilayer humidity-responsive actuators are generally composed of actuating and supporting layers of different materials with largely different wettability. Such kinds of bilayer actuators suffer from low adhesive force between the two layers during usage. This study demonstrates the preparation of humidity-responsive bilayer actuators that have the same materials in the actuating and supporting layers to avoid the adhesive issue. The bilayer actuators consist of a porous poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) layer and a nonporous PAA/PAH layer that are fabricated by exponentially layer-by-layer assembly method. At a high/low relative humidity (RH), the nonporous PAA/PAH layer can efficiently expand/shrink by absorbing/desorbing water while the volume expansion/shrinkage of the porous PAA/PAH layer in an environment with changed humidity is significantly suppressed by the micrometer-sized pores. The largely different expansion/shrinkage of the nonporous and porous PAA/PAH layers when subjected to humidity changes enables rapid and reversible rolling/unrolling motions of the bilayer actuator. The bilayer actuator shows a faster rolling speed and a larger bending curvature when subjected to a larger humidity increase.
In press , doi: 10.1007/s10118-018-2167-y
[Abstract](13) [FullText HTML](5) [PDF 730KB](0)
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Response speed is one of the most important evaluation criteria for CO2 sensors. In this work, we report an ultrafast CO2 fluorescent sensor based on poly[oligo(ethylene glycol) methyl ether methacrylate]-b-poly[N,N-diethylaminoethyl methacrylate-r-4-(2-methylacryloyloxyethylamino)-7-nitro-2,1,3-benzoxadiazole] [POEGMA-b-P(DEAEMA-r-NBDMA)], in which DEAEMA units act as the CO2-responsive segment and 4-nitrobenzo-2-oxa-1,3-diazole (NBD) is the chromophore. The micelles composed of this copolymer could disassemble in 2 s upon CO2 bubbling, accompanying with enhanced fluorescence emission with bathochromic shift. Furthermore, the quantum yield of the NBD chromophore increases with both the CO2 aeration time and the NBD content. Thus we attribute the fluorescent enhancement to the inhibition of the photo-induced electron transfer between unprotonated tertiary amine groups and NBD fluorophores. The sensor is durable although it is based on " soft” materials. These micellar sensors could be facilely recycled by alternative CO2/Ar purging for at least 5 times, indicating good reversibility.
In press , doi: 10.1007/s10118-018-2155-2
[Abstract](13) [FullText HTML](7) [PDF 1601KB](0)
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The mesoscopic simulation technique was applied to describe the phase separation behavior of polyimide blends and used for design of immiscible polyimide/BN blend films with enhanced thermal conductivity. The simulation equilibrium morphologies of different poly(amic acid) (PAA) blend systems were investigated and compared with optical images of corresponding polyimide blend films obtained by experiment. The immiscible polyimide blend films containing nano-/micro-sized BN with vertical double percolation structure were prepared. The result indicated that the thermal conductivity of polyimide blend film with 25 wt% nano-sized BN reached 1.16 W/(m·K), which was 236% increment compared with that of the homogenous film containing the same BN ratio. The significant enhancement in thermal conductivity was attributed to the good phase separation of polyimide matrix, which made the inorganic fillers selectively localized in one continuous phase with high packing density, consequently, forming the effective thermal conductive pathway.
In press , doi: 10.1007/s10118-019-2180-9
[Abstract](35) [FullText HTML](20) [PDF 15448KB](5)
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This work is focused on simulating the rheological effects in polyamide. An experimental study is carried out in order to assess such features of polyamide as: the hysteretic behavior, the strain rate dependence, and the stress relaxation. The material response in tension is investigated. Digital images correlation method (DIC) is employed in order to measure the material compressibility. A newly developed constitutive model, which was previously used to simulate the mechanical response of polyethylene subjected to moderate strains and compressive loadings, is applied to capture the large strain, inelastic behavior of polyamide in tension. The gathered experimental data are utilized to determine the values of constitutive constants of viscoelasticity and plasticity, which describe the rheological properties of polyamide. The determined material parameters are included in the text. Different strategies for evaluating the material parameters are discussed. The proposed constitutive equation is implemented into the finite element (FE) system, ABAQUS, by taking advantage of the user subroutine UMAT, which allows to define custom material laws. Some exemplary FE simulations that were used to investigate the performance of the developed subroutine are described.
In press , doi: 10.1007/s10118-019-2178-3
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Blend based polymer nanocomposites, comprising Janus nanoparticles at their polymer/polymer interface, were analytically/experimentally evaluated. The modeling procedure was performed in two stages: first, modeling of polymer/polymer interface region comprising Janus nanoparticles and second, modeling of the entire systems as a function of the variation of the blend morphology. In the first stage, the modeling procedure was performed based on the development of the model proposed by Ji et al. and in the second stage, the fundamental of Kolarik’s model was used in order to propose a developed and more practical model. It was shown that Janus nanoparticles may form dual polymer/particle interphase at polymer/polymer interface which can drastically affect the final mechanical properties of the system. Comparing the results of tensile tests imposed on different prepared samples with the predictions of the model proved its accuracy and reliability (error < 9%).
In press , doi: 10.1007/s10118-019-2183-6
[Abstract](13) [FullText HTML](5) [PDF 701KB](2)
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Four polymers containing five-membered rings in the main chain, with or without conjugation structure along the backbone and with or without conjugated pendent groups, were designed and synthesized by metathesis cyclopolymerization of functionalized α,ω-diynes, and cyclopolymerization of functionalized α,ω-dienes catalyzed by the α-diimine palladium-based catalyst, respectively. High to moderate monomer conversions were achieved. Chain structure, molecular weight, and molecular weight distribution (MWD) of the cyclopolymerization products were characterized by 1H-, 13C-NMR, FTIR, and GPC. The polymers showed regular main chain structures, moderately high molecular weight, and narrow MWD. Thermal properties and chain stacking behaviors of the polymers were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) as well as atomic force microscopy (AFM). The polymer with conjugation system in both the backbone and the pendent groups exhibited UV-Vis absorption at a much longer wavelength than those with the conjugation only in the backbone or only in the side groups. The polymers with conjugated backbone need more space for chain stacking, and the conjugated backbone causes enhanced size of polymer particles assembled from solution. The results showed that primary microstructures of the polymer exerted significant influences on the physical properties.
In press , doi: 10.1007/s10118-019-2174-7
[Abstract](9) [PDF 1067KB](0)
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Polylactide (PLA) films blended with poly(butylene adipate-co-terephthalate) (PBAT) were hot melted using a twin screw extruder with the addition of triethyl citrate (TEC) as a plasticizer and toluene diisocyanate (TDI) as a compatibilizer. The synergistic effects of the two additives on the mechanical, thermal, and morphological properties of the PLA/PBAT blend films were investigated. The influence of TEC content on the plasticized PLA films and the effect of TDI’s presence on the PLA/PBAT blend films were also studied by comparing them with neat PLA. The results showed a pronounced increase in elongation at break of the plasticized PLA films with increasing TEC levels, but a slight reduction in thermal stability. Also, the addition of TEC and TDI to the blend system not only synergistically enhanced the tensile properties and tensile-impact strength of the PLA/PBAT blends, but also affected their crystallinity and cold crystallization rate, a result of the improvement of interfacial interaction between PLA and PBAT, including the enhancement of their chain mobility. The synergy of the plasticization and compatibilization processes led to the improvement of tensile properties, tensile-impact strength, and compatibility of the blends, accelerating cold crystallization without affecting crystallization.
In press , doi: 10.1007/s10118-019-2175-6
[Abstract](46) [FullText HTML](17) [PDF 1071KB](11)
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Phenethyl-bridged DOPO derivative (DiDOPO) was combined with graphene nanosheets (GNSs) in epoxy resin (EP) to improve its flame retardancy. The results indicated that the introduction of only 1.5 wt% DiDOPO/1.5 wt% GNS in EP increased the limited oxygen index (LOI) from 21.8% to 32.2%, hence meeting UL 94 V-0 rating. The thermogravimetric analyses revealed that char yield rose in presence of GNSs to form thermally stable carbonaceous char. The decomposition and pyrolysis products in gas phase were characterized by thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), and the release of large amounts of phosphorus was detected in the gas phase. The evaluation of flame-retardant effect by cone calorimetry demonstrated that GNSs improved the protective-barrier effect of fire residue of EP/DiDOPO/GNS. The latter was further confirmed by digital photography and scanning electron microscopy (SEM). Also, Raman spectroscopy showed that GNSs enhanced graphitization degree of the resin during combustion. Overall, the combination of DiDOPO with GNSs provides an effective way for developing high-performance resins with improved flame retardancy.
In press , doi: 10.1007/s10118-019-2176-5
[Abstract](32) [FullText HTML](13) [PDF 1444KB](3)
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Based on the preparative experiments of the light-emitting diode (LED) encapsulant, three types of monomer models with different functional groups are carried out to study the polymerization process by dynamic Monte Carlo (DMC) simulation and bond fluctuation model (BFM). We calculate the degree of polymerization, the radius of gyration and the frequency of void spheres to discuss the polymerization process, the molecular size and the spatial distribution at different volume fractions and proportions. Our results are in agreement with Grest’s decay rate and Flory’s scale law. Simulations show that the polymerization process depends on the appropriate volume fraction and proportion exceedingly, and the volume contraction in the polymerization process can also be observed in this study. These investigations could provide some insights into the understanding of the polymerization process of the encapsulant and help us to adjust the parameters in later experiments.
In press , doi: 10.1007/s10118-018-2152-5
[Abstract](133) [FullText HTML](61) [PDF 713KB](3)
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Rare attention has been paid to the comparison between a monomer and its corresponding polymer in terms of the optoelectronic characteristics. In this article, a model H-shaped molecule and its corresponding polymer, both of which exhibited similar properties including blue emission and solution processing, were designed and synthesized. Optoelectronic properties and various kinds of stability features, including the thermostabilities, spectral stabilities and amplified spontaneous emission characteristic of the monomer and polymer were investigated. In general, the corresponding polymer PH exhibited similar optoelectronic properties but deteriorated stabilities compared with its H-shaped monomer H-1 probably owing to the similar chemical structure but the wider molecular weight distribution and metal catalyst residue. Importantly, monomer H-1 displayed a comparable ASE threshold value with its polymer PH, suggesting that H-shaped fluorene-based small molecules may be more promising optical gain media in solid state amplifers and lasers.
In press , doi: 10.1007/s10118-019-2179-2
[Abstract](41) [FullText HTML](19) [PDF 914KB](8)
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A series of co-polyimide (PI) fibers containing phenylphosphine oxide (PPO) group were synthesized by incorporating the bis(4-aminophenoxy) phenyl phosphine oxide (DAPOPPO) monomer into the PI molecular chain followed by dry-jet wet spinning. The effects of DAPOPPO molar content on the atomic oxygen (AO) resistance of the fibers were investigated systematically. When the AO fluence increased from 0 atoms·cm−2 to 3.2 × 1020 atoms·cm−2, the mass loss of the fibers showed the dependence on DAPOPPO molar content in co-PI fibers. The PI fiber containing 40% DAPOPPO showed lower mass loss compared to those containing 0% and 20% DAPOPPO. At higher AO fluence, the higher DAPOPPO content gave rise to dense carpet-like surface of fibers. XPS results indicated that the passivated phosphate layer was deposited on the fiber surface when exposed to AO, which effectively prevented fiber from AO erosion. With the DAPOPPO content increasing from 0% to 40%, the retentions of tensile strength and initial modulus for the fibers exhibited obvious growth from 44% to 68%, and 59% to 70%, after AO exposure with the fluence of 3.2 × 1020 atoms·cm−2. The excellent AO resistance benefits the fibers for application in low Earth orbit as flexible construction components.
In press , doi: 10.1007/s10118-018-2158-z
[Abstract](159) [FullText HTML](114) [PDF 831KB](8)
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Chronic inflammatory responses induced by macrophages play a pivotal role in the progression of atherosclerosis. In the present study, a multifunctional nanocarrier based on poly(ethylene glycol)-block-poly(L-aspartic acid) grafted with diethylenetriamine, lysine and cholic acid (PEG-PAsp(DETA)-Lys-CA2) polymer was synthesized for co-delivery of andrographolide and siRNA targeting Notch1 gene to alleviate the inflammatory response in macrophages. The nanocarrier exerted low cytotoxicity as well as high performance in drug/siRNA co-delivery. In vitro studies demonstrated the co-delivery of andrographolide and Notch1 siRNA not only significantly inhibited lipopolysaccharide (LPS)-activated interleukin-6 (IL-6) and monocytes chemotactic protein 1 (MCP-1) expression as well as blocked nuclear factor-κB (NF-κB) signal activation, but also interfered the Notch1 gene expression and increased anti-inflammatory cytokines such as interleukin-10 (IL-10) and arginase-1 expression obviously in macrophages. These results suggested that the combination therapy based on Notch1 siRNA and andrographolide co-delivered nanocarrier, i.e. suppressing the expression of pro-inflammatory cytokines while simultaneously increasing anti-inflammatory factors expression, be a feasible strategy for atherosclerosis treatment.
In press , doi: 10.1007/s10118-018-2150-7
[Abstract](113) [FullText HTML](51) [PDF 748KB](6)
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Despite the good biodegradable and mechanical properties, poly(lactic acid) still suffers from a highly inherent flammability, which restricts its applications in the electric and automobile fields. In order to improve the flame retardancy of PLA, in this work, melamine polyphosphate (MPP) and zinc bisdiethylphosphinate (ZnPi) were firstly incorporated into PLA, and the synergistic effect of them on flame retardance of PLA was investigated using limiting oxygen index (LOI), UL-94 vertical measurement, scanning electron microscopy (SEM) and cone calorimeter tests etc. The results showed that PLA composite with 15 wt% of MPP/ZnPi (3:2) had the best flame-retardant efficiency with LOI value of 30.1 and V0 rating in UL-94 tests, which was far better than using MPP or ZnPi alone. What is more, although a wide range of flame retardants have been developed to reduce the flammability, so far, they normally compromise the mechanical properties of PLA. On the premise of maintaining good flame-retardant performance, we improved the toughness of flame-retardant PLA composite, and the impact strength of flame-retardant PLA composite was more than tripled (8.08 kJ/m2) by adding thermoplastic urethanes (TPU). This work offers an innovative method for the design of the unique integration of extraordinary flame retardancy and toughening reinforcement for PLA materials.
In press , doi: 10.1007/s10118-018-2143-6
[Abstract](143) [FullText HTML](63) [PDF 1328KB](10)
Abstract:
Imidazolium-based elastomeric ionomers (i-BIIR) were facilely synthesized by ionically modified brominated poly(isobutylene-co-isoprene) (BIIR) with different alkyl chain imidazole and thoroughly explored as novel toughening agents for poly(lactic acid) (PLA). The miscibility, thermal behavior, phase morphology and mechanical property of ionomers and blends were investigated through dynamic mechanical analyses (DMA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile and impact testing. DMA and SEM results showed that better compatibility between the PLA and i-BIIR was achieved compared to the PLA/unmodified BIIR elastomer. A remarkable improvement in ductility with an optimum elongation at break up to 235% was achieved for the PLA/i-BIIR blends with 1-dodecylimidazole alkyl chain (i-BIIR-12), more than 10 times higher than that of pure PLA. The impact strengths of PLA were enhanced from 1.9 kJ/m2 to 4.1 kJ/m2 for the PLA/10 wt% i-BIIR-12 blend. Toughening mechanism had been established by systematical analysis of the compatibility, intermolecular interaction and phase structures of the blends. Interfacial cavitations initiated massive shear yielding of the PLA matrix owing to a suitable interfacial adhesion which played a key role in the enormous toughening effect in these blends. We believed that introducing imidazolium group into the BIIR elastomer was vital for the formation of a suitable interfacial adhesion.
In press , doi: 10.1007/s10118-018-2164-1
[Abstract](113) [FullText HTML](53) [PDF 1370KB](27)
Abstract:
The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber (CF) composites. To this end, a facile interfacial strategy for fabricating flame-retardant carbon fibers decorated by bio-based polyelectrolyte complexes (PEC) consisting of chitosan (CH) and ammonium polyphosphate (APP) was developed, and its corresponding fire-retarded epoxy resin composites (EP/(PEC@CF)) without any other additional flame retardants were prepared. The decorated CFs were characterized by SEM-EDX, XPS and XRD, indicating that the flame-retardant PEC coating was successfully constructed on the surface of CF. Thanks to the nitrogen- and phosphorous-containing PEC, the resulting composites exhibited excellent flame retardancy as the limiting oxygen index (LOI) increased from 31.0% of EP/CF to 40.5% and UL-94 V-0 rating was achieved with only 8.1 wt% PEC. EP/(PEC8.1@CF) also performed well in cone calorimetry with the decrease of peak-heat release rate (PHRR) and smoke production rate (SPR) by 50.0% and 30.4%, respectively, and the value of fire growth rate (FIGRA) was also reduced to 3.41 kW·m−2·s−1 from 4.84 kW·m−2·s−1, suggesting a considerably enhanced fire safety. Furthermore, SEM images of the burning residues revealed that the PEC coating exhibited the dominant flame-retardant activity in condensed phase via the formation of compact phosphorus-rich char. In addition, the impact strength of the composite was improved, together with no obvious deterioration of flexural properties and glass transition temperature. Taking advantage of the features, the PEC-decorated carbon fibers and the relevant composites fabricated by the cost-effective and facile strategy would bring more chances for widespread applications.
In press , doi: 10.1007/s10118-018-2160-5
[Abstract](85) [FullText HTML](53) [PDF 1234KB](10)
Abstract:
Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate (DOP) as milling medium without solvent. The obtained mixture could be directly mixed with poly(vinyl chloride) (PVC) for melt-forming, with DOP acting as plasticizer and graphene acting as conductive filler for antistatic performance. The composite showed surface resistance of 2.5 × 106 Ω/□ at 1 wt% carbon additive, significantly lower than approx. 7 wt% of raw graphite required for achieving the same level. This value is low enough for practical antistatic criterion of 3 × 108 Ω/□. The effect of filler addition on mechanical performance was minimal, or even beneficial for the milled carbon in contrast to the case of raw graphite.
In press , doi: 10.1007/s10118-018-2145-4
[Abstract](127) [FullText HTML](59) [PDF 718KB](7)
Abstract:
Modified castor oil-based epoxy resin (EP)/polyurethane (PU) grafted copolymer by glycidyl polyhedral oligomeric silsesquioxane (glycidyl POSS) was synthesized. The damping properties, thermal stability, mechanical properties and morphology of the grafted copolymer modified by glycidyl POSS were studied systematically. The results revealed that the incorporation of glycidyl POSS improved the damping performance evidently and broadened damping temperature range, especially when the glycidyl POSS content was 0.2%–1%. At the same time, there was a slight increase in thermal stability with the increase of POSS content. The tensile properties changed with the change of the copolymer’sTg, decreased at low POSS contents and increased at high POSS contents. This modified copolymer has the potential to be used as film damping material or constrained damping layer.
In press , doi: 10.1007/s10118-018-2159-y
[Abstract](70) [FullText HTML](57) [PDF 1319KB](1)
Abstract:
The synthesis and structure-property correlation of poly(N-(2-hydroxypropyl) methacrylamide) (PHPMA) conjugates with various architectures including random, block, branched or star-like structures and compositions have been thoroughly explored. However, related synthesis and structure-property data are still lacking for comb-like PHPMA. In this work, we report the synthesis of comb-like PHPMA copolymer-doxorubicin (DOX) conjugates with different backbone/side-chain lengths and location of drug moieties. Well-defined comb-like PHPMA-DOX conjugates are obtained via the combination of controlled radical polymerization and fractional precipitation techniques. The influences of structural factors on the biological properties such as cellular uptake, blood circulation and tumor accumulation have been investigated. Long blood circulation and efficient tumor accumulation can be achieved by proper control of the comb number, length and location of drug moieties. These facile comb-like structures possess great potentials in future theranostics for brachytherapy or surgical navigation.
In press , doi: 10.1007/s10118-018-2148-1
[Abstract](81) [FullText HTML](47) [PDF 2562KB](7)
Abstract:
In this study, the effects of halloysite nanotubes (HNTs) reinforcement in expandable graphite based intumescent fire retardant coatings (IFRCs) developed using a polydimethylsiloxane (PDMS)/phenol BA epoxy system were investigated. Intumescent coating formulations were developed by incorporating different weight percentages of HNTs and PDMS in basic intumescent ingredients (ammonium polyphosphate/melamine/boric  acid/expandable  graphite, APP/MEL/BA/EG). The performance of intumescent formulations was investigated by furnace fire test, Bunsen burner fire test, field emission electron microscopy (FESEM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier transform infrared analysis (FTIR). The Bunsen burner fire test results indicated that the fire performance of HNTs and PDMS reinforced intumescent formulation has improved due to the development of silicate network over the char residue. Improved expansion in char residue was also noticed in the formulation, SH(3), due to the minimum decomposition of char carbon. FESEM and TEM results validated the development of silicate network over char layer of coating formulations. A considerable mass loss difference was noticed during thermal gravimetric analysis (TGA) of intumescent coating formulations. Reference formulation, SH(0) with no filler, degraded at 300 °C and lost 50% of its total mass but SH(3), due to synergistic effects between PDMS and HNTs, degraded above 400 °C and showed the maximum thermal stability. XRD analysis showed the development of thermally stable compound mulltie, due to the synergism of HNTs and siloxane during intumescent reactions, which enhanced fire performance. FTIR analysis showed the presence of incorporated siloxane and silicates bonds in char residue, which endorsed the toughness of intumescent char layer produced. Moreover, the synergistic effect of HNTs, PDMS, and other basic intumescent ingredients enhanced the polymer cross-linking in binder system and improved fire resistive performance of coatings.
In press , doi: 10.1007/s10118-018-2139-2
[Abstract](195) [FullText HTML](93) [PDF 617KB](14)
Abstract:
Poly(methyl methacrylate-b-styrene) (PMMA-b-PS) block copolymers are synthesized by two consecutive ATRPs and fractionated into four fractions. The halogen chain end fidelity (CEF) in PMMA-b-PS is quantified based on the analysis of each fraction. Compared to ethyl 2-phenyl-2-bromoacetate/CuBr/2,2′-bipyridine (EPBA/CuBr/bpy) and CuBr/N,N,N′,N″,N″-pentamethyldiethylene-triamine (CuBr/PMDETA) catalysts, PMMA-b-PS synthesized using p-toluenesulfonyl chloride/CuCl/bpy (TsCl/CuCl/bpy) and CuCl/PMDETA catalysts has a higher halogen CEF and a better control on molecular weight.
In press , doi: 10.1007/s10118-018-2163-2
[Abstract](61) [FullText HTML](32) [PDF 852KB](2)
Abstract:
In press , doi: 10.1007/s10118-018-2134-7
[Abstract](176) [FullText HTML](117) [PDF 2251KB](7)
Abstract:
In this study, we attempt to prepare a new blending system of poly(vinylidene fluoride) (PVDF) and aliphatic polyketone (POK) by melt compounding. The latter is a promising engineering plastic with comprehensive mechanical performances. When POK acted as minor phase to homogeneously disperse in and intimately contact with PVDF matrix, the brittle tensile behavior of neat PVDF transferred into a remarkably flexible manner (the elongation at break increased for 20 times), and more interestingly, the room-temperature durability of β-form PVDF in the uniaxially drawn blend film was obviously better than that in the neat PVDF film. Fourier transform infrared spectroscopy revealed that specific dipole interaction existed between CF2 group of PVDF and C＝O group of POK. The intermolecular dipolar interaction induced good compatibility in the PVDF/POK blends, as evidently proved by fine two-phase morphology and decreased melting points of POK crystals. Therefore, the good compatibility and interfacial enhancement are responsible for the improvement of the stretch ductility and β-form room-temperature durability of the PVDF/POK blends.
In press , doi: 10.1007/s10118-018-2135-6
[Abstract](168) [FullText HTML](92) [PDF 666KB](10)
Abstract:
The phase transition from tetragonal form II to hexagonal form I was studied for the butene-1/ethylene and butene-1/1,5-hexadiene random copolymers, which have comparable molecular weight but distinct linear ethylene and ringlike methylene-1,3-cyclopentane (MCP) structural co-units, respectively. It is known that this solid phase transition follows the nucleation-growth mechanism, so the stepwise annealing protocol was utilized to investigate the influences of co-units on the optimal nucleation and growth temperatures. Compared with optimal nucleation and growth temperatures of −10 and 35 °C, respectively, in polybutene-1 homopolymer, two butene-1/ethylene copolymers with 1.5 mol% and 4.3 mol% co-units have the slightly lower optimal nucleation temperature of −15 °C but much higher optimal growth temperature of 50 °C. Clearly, the effect of ethylene co-unit is more significant on varying optimal temperature for growth than for nucleation. Furthermore, when the incorporated co-unit is ringlike MCP, the optimal nucleation temperature is −15 °C for 2.15 mol% co-units, the same with above BE copolymers, but −13 °C for a very low concentration of 0.65 mol%. Interestingly, the optimal growth temperature of butene-1/1,5-hexadiene copolymers with 0.65 mol%−2.15 mol% MCP co-units increases to 55 °C, which is also independent on co-unit concentration. These obtained values of optimal temperatures provide crucial parameters for rapid II-I phase transition.
In press , doi: 10.1007/s10118-019-2177-4
[Abstract](34) [FullText HTML](9) [PDF 735KB](19)
Abstract:
The nature of the crystalline phase of poly(vinylidene fluoride) (PVDF) in compatible blends with poly(ethyl methacrylate) (PEMA) was investigated by using X-ray diffraction (XRD), infrared microscopy (IR) and differential scanning calorimetry (DSC). The β phase of PVDF was observed after quenching from the melt and further annealing above the glass transition temperature over a composition range. The PVDF/PEMA blend with weight ratio of 3:2 has formed higher content of PVDF β crystals than others. By taking advantage of fast cooling rate of ultrafast differential scanning calorimeter (UFDSC), the quenching process of blends was modeled and tested simultaneously, and the melting behavior of β crystals in all blends was investigated. Three types of crystallization behavior of β phase PVDF in blends were found after quenching-annealing at different temperatures.
In press , doi: 10.1007/s10118-019-2187-2
[Abstract](21) [FullText HTML](12) [PDF 1656KB](1)
Abstract:
Cellular foams are widely applied as protective and energy absorption materials in both civil and military fields. A facile and simple one-step heating method to fabricate polymeric foams is measured by adopting thermally expandable microspheres (TEMs). The ideal foaming parameters for various density foams were determined. Moreover, a mechanical testing machine and split Hopkinson bar (SHPB) were utilized to explore the quasi-static and dynamic compressive properties. Results showed that the cell sizes of the as-prepared TEMs foams were in the micrometer range of 11 μm to 20 μm with a uniform cell size distribution. All the foams exhibited good compressive behavior under both quasi-static and high strain rate conditions, and were related to both foam densities and strain rates. The compressive strength of the TEMs foams at 8400 s−1 was up to 4 times higher than that at 10−4 s−1. The effects exerted by the strain rate and sample density were evaluated by a power law equation. With increasing density, the strain rate effect was more prominent. At quasi-static strain rates below 3000 s−1 regime, initial cell wall buckling and subsequent cellular structure flattening were the main failure mechanisms. However, in the high strain rate (HSR) regime (above 5000 s−1), the foams were split into pieces by the following transverse inertia force.
In press , doi: 10.1007/s10118-019-2186-3
[Abstract](31) [FullText HTML](21) [PDF 529KB](8)
Abstract:
The solubility of initiator determines its distribution and the roles played in emulsion polymerization as well as the final products, but this is still lack of systematic investigation. The present work focuses on this issue by comparing the kinetic behaviors and product properties of styrene emulsion polymerization initiated by 2,2-azoisobutyronitrile (AIBN) and potassium persulphate (KPS). Compared to KPS-initiated emulsion polymerization, the AIBN-initiated polymerization was found to be insensitive to the type of emulsifier, and have high polymerization rate as well as narrow molecular weight distribution and particle size distribution. This result indicates the effective free radicals are generated in micelles or colloids, which could decrease the proportion of homogeneous nucleation and make the process and product more controllable. As a consequence, there is a linear relationship between molecular weight of product and AIBN concentration in lg-lg coordinate. It provided a reference for the preparation of latexes with specified molecular weight and supported the possibility of the coexistence of multiple free radicals in one micelle or colloid when using oil-soluble initiator.
In press , doi: 10.1007-S10118-019-2188-1
[Abstract](23) [FullText HTML](5) [PDF 1144KB](1)
Abstract:
We present here a series of perylene diimide (PDI) based isomeric conjugated polymers for the application as efficient electron acceptors in all-polymer solar cells (all-PSCs). By copolymerizing PDI monomers with 1,4-diethynylbenzene (para-linkage) and 1,3-diethynylbenzene (meta-linkage), isomeric PDI based conjugated polymers with parallel and non-parallel PDI units inside backbones were obtained. It was found that para-linked conjugated polymer (PA) showed better solubility, stronger π-π stacking, more favorable blend morphology, and better photovoltaic performance than those of meta-linked conjugated polymers (PM) did. Device based on PTB7-Th:PA (PTB7-Th:poly{4,8-bis[5-(2-ethylhexyl)-thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophene-4,6-diyl}) showed significantly enhanced photovoltaic performance than that of PTB7-Th:MA (3.29% vsrsus 0.92%). Moreover, the photovoltaic performance of these polymeric acceptors could be further improved via a terpolymeric strategy. By copolymerizing a small amount of meta-linkages into PA, the optimized terpolymeric acceptors enabled to enhance photovoltaic performance with improved the short-circuit current density (Jsc) and fill factor (FF), resulting in an improved power conversion efficiency (PCE) of 4.03%.
In press , doi: 10.1007/s10118-019-2185-4
[Abstract](18) [FullText HTML](14) [PDF 808KB](0)
Abstract:
The SiO2 nanoparticles were coated on the surface of graphene oxide (GO) by sol-gel method to get the SiO2-G compound. The SiO2-G was restored and oleophylically modified to prepare hydrophobic modified SiO2-G (HM-SiO2-G) which was subsequently added to silicone rubber matrix to prepare two-component room temperature vulcanized (RTV-2) thermal conductive silicone rubber. The morphology, chemical structure and dispersity of the modified graphene were characterized with SEM, FTIR, Raman, and XPS methods. In addition, the heat-resistance behavior, mechanical properties, thermal conductivity, and electrical conductivity of the RTV-2 silicone rubber were also studied systematically. The results showed that the SiO2 nanoparticles were coated on graphene oxide successfully, and HM-SiO2-G was uniformly dispersed in RTV-2 silicone rubber. The addition of HM-SiO2-G could effectively improve the thermal stability, mechanical properties and thermal conductivity of RTV-2 silicone rubber and had no great influence on the electrical insulation performance.
In press , doi: 10.1007/s10118-019-2184-5
[Abstract](21) [FullText HTML](11) [PDF 686KB](7)
Abstract:
The structural transformation of mesophase to crystalline phase of strain-induced poly(L-lactic acid) has been investigated by differential scanning calorimetry (DSC) and in situ temperature dependent polarized Fourier transform infrared (FTIR) spectroscopy. It is found that, as the drawing temperature increases, melting of strain-induced mesophase in the heating process can remarkably interfere the crystallization behavior subsequently. Coupling with in situ polarized FTIR, from 60 °C to 76 °C, the mesophase melts partially rather than completely melting, and changes immediately to three-dimensional ordered structure. Of particular note, through monitoring the subtle spectral change in the critical phase transformation temperature from 60 °C to 64 °C, it is clearly demonstrated that relaxation of oriented amorphous chains initially takes place prior to the melting of mesophase.
In press , doi: 10.1007/s10118-019-2181-8
[Abstract](25) [FullText HTML](21) [PDF 896KB](7)
Abstract:
An electrochromic copolymer film of 2-(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-6-yl)-7-(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-8-yl)-9H-carbazole (M1) and 4,7-bis(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (M2) was prepared via electrochemical technique. The copolymerization was performed with one to one monomer feed ratio. Electrochemical and optical properties of the resulting copolymer film (P3) and the homopolymer films of M1 and M2 (P1 and P2) were investigated by using cyclic voltammetry and UV-Vis spectrometry techniques, and the corresponding results were compared. Incorporation of M1 and M2 into copolymer matrix was clearly observed on the resulting cyclic voltammograms and UV-Vis spectra. P3 covered the visible regions coming from both P1 and P2, and exhibited a neutral state darker color than those of homopolymers. P3 film was found to have a multichromic behavior, appearing as brown in its neutral state while changing its color upon oxidation to dark-gray (at about 0.3 V), to blue (at about 0.6 V) and finally to grayish cyan (beyond 0.9 V), with a corresponding optical band gap of 1.65 eV.
In press , doi: 10.1007/s10118-019-2182-7
[Abstract](93) [FullText HTML](20) [PDF 1005KB](15)
Abstract:
Microgels with a thermo-sensitive poly(N-isopropylacrylamide) (polyNIPAm) backbone and bis-imidazolium (VIM) ionic cross-links, denoted as poly(NIPAm-co-VIM), were successfully prepared. The as-synthesized ionic microgels were converted to nanoreactors, denoted as Au@PNI MGs, upon generation and immobilization of gold nanoparticles (Au NPs) of 5–8 nm in size into poly(NIPAm-co-VIM). The content of Au NPs in microgels could be regulated by controlling the 1,6-dibromohexane/vinylimidazole molar ratio in the quaternization reaction. The microgel-based nanoreactors were morphologically spherical and uniform in size, and presented reversible thermo-sensitive behavior with volume phase transition temperatures (VPTTs) at 39–40 °C. The Au@PNI MGs were used for the reduction of 4-nitrophenol, of which the catalytic activity could be modulated by temperature.

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2018, 36(10): -
[Abstract](27) [PDF 51128KB](2)
Abstract:
2018, 36(10): 1093-1102   doi: 10.1007/s10118-018-2169-9
[Abstract](32) [FullText HTML](4) [PDF 21461KB](4)
Abstract:
Synchrotron radiation (SR) provides highly brilliant light with tunable wavelength from hard X-ray to far infrared, on which scattering, spectroscopy and imaging techniques with high time and spatial resolutions have been developed for in situ study on biological system and materials like polymer. With examples on flow-induced crystallization of polymer, deformation of nanoparticle filler network in rubber composite and necking propagation in tensile stretch, current work attempts to demonstrate the advantages of in situ synchrotron radiation X-ray scattering, X-ray nano-CT and infrared imaging in the study of deformation-induced multi-scale structural evolutions of polymers. With time resolution up to sub-ms, synchrotron radiation is expected to play a great role in understanding non-equilibrium polymer physics under processing and service conditions, while high-throughput characterization platform based on synchrotron radiation opens the possibility to establish polymer Materials Genome database in processing parameter space within reasonable time, which can serve as the roadmap for industrial polymer processing and accelerate material innovation.
2018, 36(10): 1103-1113   doi: 10.1007/s10118-018-2170-3
[Abstract](18) [PDF 0KB](3)
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The interfacing study of biopolymer and supramolecular chemistry enables a better understanding of fundamental biochemical processes and the creating of new high-performance biomaterials. In this review, we introduced an " in vivo self-assembly” strategy which means in situ construction of functional self-assembled superstructures in specific physiological or pathological conditions in cell, tissue or animal levels that exhibit diverse biomedical effects. By using this strategy, unexpected phenomena and insights, e.g, assembly/aggregation induced retention (AIR) effect have been demonstrated where the self-assembled nanostructures showed extraordinary enhanced accumulation and retention of therapeutics in targeted sites.
2018, 36(10): 1114-1122   doi: 10.1007/s10118-018-2133-8
[Abstract](209) [FullText HTML](106) [PDF 1239KB](7)
Abstract:
The siliceous frustules of diatom algae contain complex proteins known as silaffins, which consist of a peptide chain with grafted polyamine chains. These polyamines contain twenty or more nitrogen atoms with trimethylene groups between the nitrogens. We synthesized a set of polymers containing grafted long-chain polyamine fragments by using acryloyl chloride (ACh) polymers and activated acrylic acid copolymers as the starting materials. The new polymers contained 0.05 mol%−3.2 mol% of polyamine chains, which corresponded to 0.06−3.56 mmol·g−1 amine groups. The new amine-containing polymers formed complexes with short (19-21-mer) deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) strands, and these complexes penetrated into model yeast cells and A549 lung cancer cell. This study demonstrates the potential of these species based on long-chain polyamines to serve as novel gene delivery systems.
2018, 36(10): 1123-1128   doi: 10.1007/s10118-018-2129-4
[Abstract](171) [FullText HTML](149) [PDF 509KB](8)
Abstract:
A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and ε-caprolactone, exhibiting notably high activity at ambient temperature. The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading (0.025 mol%) within 18 min. The influence of various monomers as well as the polymerization mechanism have also been discussed.
2018, 36(10): 1129-1138   doi: 10.1007/s10118-018-2128-5
[Abstract](188) [FullText HTML](126) [PDF 1848KB](8)
Abstract:
A series of random terpolymers P2P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol% and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor (D-A) type copolymer PTB7-Th (P1). All polymers showed similar molecular weight with number-average molecular weight (Mn) and weight-average molecular weight (Mw) in the range of (59−74) and (93−114) kg·mol−1, respectively, to ensure a fair comparison on the structure-property relationships. Compared with the control copolymer PTB7-Th, the random terpolymers exhibited enhanced absorption intensity in a wide range from 400 nm to 650 nm in both solution and film as well as in polymer/PC71BM blends. From grazing incident wide-angle X-ray diffraction (GIWAXS), compared with the regularly alternated copolymer PTB7-Th, the random terpolymers demonstrated mild structural disorder with reduced (100) lamellar stacking and slightly weakened (010) π-π stacking for the polymers as well as slightly reduced PC71BM aggregation in polymer/PC71BM blends. However, the measured hole mobility for terpolymers ((1.20−3.73) × 10−4 cm2·V−1·s−1) was evaluated to be comparable or even higher than 1.35 × 10−4 cm2·V−1·s−1 of the alternative copolymer. Enhanced average power conversion efficiency (PCE) from 7.35% to 8.11% and 7.79% to 8.37% was observed in both conventional and inverted device architectures from copolymer P1 to terpolymers P4, while further increasing the 2,2-bithiophene feed ratio decreased the PCE.
2018, 36(10): 1139-1149   doi: 10.1007/s10118-018-2141-8
[Abstract](188) [FullText HTML](64) [PDF 2760KB](29)
Abstract:
Photothermo-chemotherapy, as a new strategy for cancer treatment, incorporates the complementary advantages of photothermal therapy and chemotherapy. In this study, a pH-sensitive diblock copolymer poly(aspartic acid-butanediamine)-poly(2-(diisopropylamino)ethyl methacrylate) (PAsp(DAB)-PDPA) was synthesized and self-assembled into doxorubicin-loaded micelle, which was further used as a template to form a gold nanoshell. After further modification with poly(ethylene glycol), the resulting nanoplatform provided good biocompatibility and desirable photo-thermal conversion efficiency to facilitate photothermal therapy. Meanwhile the nanoparticle also exhibited pH sensitivity, which prevented drug loss while circulating in the blood but enabled rapid drug release after endocytosis. An improved effect was achieved with the combination of photothermal therapy and chemotherapy. In addition, systemic delivery of the nanoplatform could be monitored by photoacoustic tomography. Thereby, this multifunctional nanoplatform would be highly potential for the diagnosis and therapy of cancer.
2018, 36(10): 1150-1156   doi: 10.1007/s10118-018-2130-y
[Abstract](256) [FullText HTML](123) [PDF 772KB](19)
Abstract:
Polyureas (PU) are well known as a class of high impact engineering materials, and widely used also in emerging advanced applications. As a general observation, most of them are only soluble in a very limited number of highly protonic solvents, which makes their chemical structure analysis a great challenge. Besides the presence of abundant hydrogen bonding, the poor solubility of PU in common organic solvents is often ascribed to the formation of biuret crosslinking in their molecular chains. To clarify the presence of biuret groups in PU has been of great interest. To this end, two samples, based on hexamethylene diisocyanate (HDI) and toluene diisocyanate (TDI) respectively, were synthesized by precipitation polymerization of each of these diisocyanates in water-acetone at 30 °C. Their chemical structures were analyzed by high resolution magic angle spinning (HR-MAS) NMR, and through comparison of their NMR spectra with those of specially prepared biuret-containing polyurea oligomers, it was concluded that biuret group was absent in all the PU prepared at 30 °C. In addition, this NMR analysis was also applied to a PU obtained by copolymerization of TDI with ethylene diamine (EDA) and water at 65 °C in EDA aqueous solution. It was confirmed that biuret unit was also absent in this PU and that EDA was more active than water towards TDI. The presence of EDA was crucial to the formation of uniform PU microspheres. This study provides therefore a reliable method for the analysis of PU chemical structure.
2018, 36(10): 1157-1167   doi: 10.1007/s10118-018-2144-5
[Abstract](161) [FullText HTML](99) [PDF 8923KB](50)
Abstract:
Poly(ether imide) (PEI) membrane with enhanced antifouling property was successfully prepared in a mild and simple procedure. The virgin membrane was firstly functionalized with an aqueous solution of diamino-terminated poly(ethylene oxide) block copolymer (PEG-diamine). Glutaraldehyde was used in a second step as a linker to chemically attach additional PEG-diamine to the primary amine groups grafted on PEI membrane surface. Immobilization of PEG segments was confirmed using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. Ultrafiltration experiments revealed that the enhancement of a PEG coverage on the membrane surface provided superior anti-protein-fouling property. Cycles of protein filtration also demonstrated that the antifouling surface was stable over time and excellent ultrafiltration performance could be maintained without the need of harsh cleansing operation.
2018, 36(10): 1168-1174   doi: 10.1007/s10118-018-2127-6
[Abstract](201) [FullText HTML](128) [PDF 737KB](12)
Abstract:
Hyper-crosslinked polymers (HCPs) are promising materials for gas capture and storage because of their low cost and easy preparation. In this work, we report the massive preparation of coumarone-indene resin-based hyper-crosslinked polymers via one-step Friedel-Crafts alkylation. Low-cost coumarone-indene resin serves as the new building block and chloroform is employed as both solvent and external crosslinker. A maximum surface area of 966 m2·g−1 is achieved, which is comparable with that of previously-reported coal tar-based porous organic polymers. Most importantly, a large number of heteroatoms including inherent oxygen atoms and introduced chlorine atoms in obtianed HCPs further enhance the interaction between specific sorbate molecule and adsorbent. Therefore, optimal structural and chemical property endow the new coumarone-indene resin-based HCPs with decent gas storage capacity (14.60 wt% at 273 K and 0.1 MPa for CO2; 1.18 wt% at 77.3 K and 0.1 MPa for H2). These results demonstrate that new HCPs are potential candidates for applications in CO2 and H2 capture.
2018, 36(10): 1175-1186   doi: 10.1007/s10118-018-2138-3
[Abstract](175) [FullText HTML](70) [PDF 3125KB](10)
Abstract:
In this work, hybrid conductive fillers of carbon black (CB) and carbon nanotubes (CNTs) were introduced into polylactide (PLA)/thermoplastic poly(ether)urethane (TPU) blend (70/30 by weight) to tune the phase morphology and realize rapid electrically actuated shape memory effect (SME). Particularly, the dispersion of conductive fillers, the phase morphology, the electrical conductivities and the shape memory properties of the composites containing CB or CB/CNTs were comparatively investigated. The results suggested that both CB and CNTs were selectively localized in TPU phase, and induced the morphological change from the sea-island structure to the co-continuous structure. The presence of CNTs resulted in a denser CB/CNTs network, which enhanced the continuity of TPU phase. Because the formed continuous TPU phase provided stronger recovery driving force, the PLA/TPU/CB/CNTs composites showed better shape recovery properties compared with the PLA/TPU/CB composites at the same CB content. Moreover, the CB and CNTs exerted a synergistic effect on enhancing the electrical conductivities of the composites. As a result, the prepared composites exhibited excellent electrically actuated SME and the shape recovery speed was also greatly enhanced. This work demonstrated a promising strategy to achieve rapid electrically actuated SME via the addition of hybrid nanoparticles with self-networking ability in binary PLA/TPU blends over a much larger composition range.
2018, 36(10): 1187-1194   doi: 10.1007/s10118-018-2132-9
[Abstract](185) [FullText HTML](127) [PDF 1492KB](9)
Abstract:
The dynamic properties of polymer melts are investigated in the range of normal liquid regime to the supercooled liquid regime. The polymer is modeled as a coarse-grained bead-spring model with chain length ranging from 5 to 160. The mean squared displacement and non-Gaussian parameter are used to describe the self diffusion of polymer beads. We find slow dynamics with decreasing temperature and increasing chain length. The time evolution of non-Gaussian parameters shows two peaks (or one peak one shoulder) in the α-relaxation time, τα, regime and sub-diffusion time regime, respectively, where the first primary peak indicates the dynamic heterogeneity stemmed from the motion of beads, and the secondary peak is the result of correlated motion along a polymer chain. Moreover, the relaxation of polymer beads shows clear two-step decay in supercooled melts and the dynamics shows growing heterogeneity with decreasing temperature. As chain length is increased, a peak of the dynamic susceptibility occurs, and the peak height, χ \begin{document}$_4^*$\end{document} , increases and then reaches a plateau. The curves of the height of the first peak of \begin{document}$\textit {α}_2^{}$\end{document} , \begin{document}$\textit {α}_2^*$\end{document} , versus \begin{document}${\textit {τ}_{\textit {α}}}$\end{document} and the curves of χ \begin{document}$_4^*$\end{document} versus \begin{document}${\textit {τ}_{\textit {α}}}$\end{document} follow two master curves for different chain lengths. Our results indicate the similarity of dynamic heterogeneity dominated by the motion of single bead even the chain length is different. It is interesting to find that the Stokes-Einstein (SE) relation between \begin{document}${\textit {τ}_{\textit {α}}}$\end{document} and diffusion coefficient D, D~τ \begin{document}${_{q}^{-1}}$\end{document} , is highly length-scale dependent. The SE relation breaks down in both normal melts regime and supercooled regime at large magnitude of wave vectors, attributed to the non-Brownian motion arising from the chain connectivity and growing heterogeneity due to supercooling. However, the SE relation is reconstructed when the probing length scale is large (at small magnitude of wave vectors). Our results show a hierarchical physical picture of the supercooled polymeric dynamics.
2018, 36(10): 1195-1199   doi: 10.1007/s10118-018-2123-x
[Abstract](196) [FullText HTML](119) [PDF 952KB](10)
Abstract:
By using polybutene-1 as a typical example, we illustrate the initiation, development and stabilization of cavities in the sample during tensile deformation. Samples with the same crystallinity, long spacing and crystalline lamellar thickness but very different sizes of spherulites were prepared via changing the melt history. Dimension of cavities during stretching the samples was determined by in situ ultra small angle X-ray scattering techniques. It turned out that the size of the cavities was bigger in the sample with larger spherulites than the one with smaller spherulites. The results show clear evidence of initiating cavities within crystalline phase at the grain-boundary of crystalline blocks, growing of cavities passing through parallel stacked lamellar crystals and amorphous layers and finally stablized by tilted lamellae at both ends of the plate-like cavities within the spherulites.
2018, 36(10): 1200-1206   doi: 10.1007/s10118-018-2122-y
[Abstract](174) [FullText HTML](118) [PDF 2219KB](5)
Abstract:
The liquid-crystal assembly of semiflexible-coil diblock copolymers with coil or semiflexible homopolymers is studied by dissipative particle dynamics simulation. Phase diagrams of the blends and orientation ordering parameters among semiflexible blocks are constructed as a function of chain stiffness and homopolymer volume fraction. For semiflexible-coil/coil blends with varying stiffness of semiflexible blocks, we display the rich phase behaviors of the system transited from coil-coil/coil to rod-coil/coil blends. The disorder-lamellae or lamellae-liquid crystalline transition and " dry brush” phenomenon induced by coil homopolymers are observed. For semiflexible-coil/semiflexible blends, adding semiflexible homopolymers also leads to a disorder-order transition and even a transition between monolayer and bilayer smectic-A phase. The results demonstrate that blending homopolymers into semiflexible copolymers can induce liquid-crystal assembly and even improve the orientation ordering of semiflexible blocks effectively.

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