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

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Corrected proof , doi: 10.1007/s10118-020-2360-7
[Abstract](106) [FullText HTML](4) [PDF 834KB](4)
Abstract:
A general model was developed to predict the temperature-dependent modulus and yield strength of different thermoplastic polymers. This model, which depends on only two parameters with clear and specific physical meanings, can describe the temperature-dependent modulus and yield strength of thermoplastic polymers over the full glass transition region. The temperature-dependent modulus and yield strength of three thermoplastic polymers were measured by uniaxial tension tests over a temperature range of 243−383 K. The predictions showed excellent agreement with the experimental data. Sensitivity analysis of model input parameters showed negligible effect on the present general model. The universality of the present general model was further validated, showing excellent agreement with published experimental data on other thermoplastic polymers and their composites.
Corrected proof , doi: 10.1007/s10118-020-2355-4
[Abstract](123) [FullText HTML](9) [PDF 240KB](6)
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Thermal, mechanical, and viscoelastic properties of polybutadiene-based rubber materials are highly dependent on polybutadiene microstructure. The use of polar modifier in association with alkyllithium is a well-known method to obtain polybutadiene with a high vinyl content. Another approach is to use bimetallic initiating species such as alkyllithium combined to heavier alkali metal alkoxide (RONa, ROK…). The polymerization control is nevertheless not achieved and several parameters were found to influence it. Using bimetallic initiating systems based on alkyllithium and a potassium alkoxide, alkyllithium structure, initiator preformation time, and initiator composition were identified as parameters influencing the anionic polymerization process of butadiene and/or polybutadiene microstructure. In addition, the use of trimetallic systems based on alkyllithium, potassium alkoxide, and alkylaluminum was investigated in order to prevent side reactions regardless of the [K]/[Li] ratio and of the initiator preformation time.
Corrected proof , doi: 10.1007/s10118-020-2350-9
[Abstract](146) [FullText HTML](8) [PDF 368KB](5)
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A generic coarse-grained bead-and-spring model, mapped onto comb-shaped polycarboxylate-based (PCE) superplasticizers, is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions. The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution. The effects of ionic strength, side-chain number, and side-chain length on the conformational behavior of PCEs in solution are explored. Single-chain equilibrium properties, including the radius of gyration, end-to-end distance and persistence length of the polymer backbone, shape-asphericity parameter, and the mean span dimension, are determined. It is found that with the increase of ionic strength, the equilibrium sizes of the polymers decrease only slightly, and a linear dependence of the persistence length of backbone on the Debye screening length is found, in good agreement with the theory developed by Dobrynin. Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes (radius of gyration and mean span) of the polymer as a whole, but also the persistence length of the backbone due to excluded volume interactions.
Corrected proof , doi: 10.1007/s10118-020-2345-6
[Abstract](302) [FullText HTML](24) [PDF 890KB](7)
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Noninvasive ultrasound is a more effective strategy for on-demand drug delivery of polymeric nanoparticles than many other stimuli. However, the preparation of ultrasound-responsive homopolymer nanoparticles is still very challenging. In this study, we disclose the regulating factors of ultrasound responsiveness of homopolymer nanoparticles and the disaggregation behavior of homopolymer nanoparticle aggregates. Homopolymer nanoparticles such as vesicles and large compound micelles (LCMs) are self-assembled from poly(methoxyethyl methacrylate) (PMEMA) and poly(amic acid) (PAA), respectively. The ultrasound responsiveness of PAA vesicles at metastable state could be regulated by tuning the self-assembly temperature (Ts), and was optimized when Ts is around the glass transition temperature (Tg) of PAA. However, the PMEMA LCMs did not respond to ultrasound as they are at stable state. On the other hand, poly(2-(2-ethoxyethoxy)ethyl acrylate) (PEEA) could self-assemble into vesicle aggregates or complex micelle aggregates, which were dissociated upon sonication. Overall, the above findings provide us with a fresh insight for designing ultrasound-responsive polymeric nanoparticles.
Corrected proof , doi: 10.1007/s10118-019-2297-x
[Abstract](277) [FullText HTML](8) [PDF 721KB](3)
Abstract:
The mechanical properties of poly(arylene sulfide sulfone) (PASS) electrospun membrane were significantly enhanced by co-electrospinning with semi-aromatic nylon poly(m-xylene adipamide) (MXD6), another engineering plastic with high thermal stability and good mechanical properties. The tensile strength of PASS membrane increased with increased incorporation of MXD6, and was tripled when 20% MXD6 was incorporated. The mechanism of the mechanical property improvement is the existence of hydrogen bonding interaction between PASS and MXD6 and between adjacent fibers at the intersections. Thermal properties of the PASS/MXD6 membranes were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), which showed that the membranes could be stably utilized up to 180 °C without any change in appearance and without decomposition. Contact angle measurements of all the membranes showed hydrophobic character. To demonstrate the potential applications of PASS/MXD6 blend membranes, their oil absorption capacities were evaluated with three oils of different viscosities, which proved that the PASS/MXD6 membranes are better absorbents than commercial non-woven polypropylene fibers. Therefore, PASS/MXD6 fibrous membranes produced by electrospinning have a great potential in practical applications.
Corrected proof , doi: 10.1007/s10118-019-2323-z
[Abstract](257) [FullText HTML](11) [PDF 495KB](6)
Abstract:
Poly(L-lactic acid) (PLLA)-based composites exhibit wide applications in many fields. However, most of hydrophilic fillers usually accelerate the hydrolytic degradation of PLLA, which is unfavorable for the prolonging of the service life of the articles. In this work, a small quantity of poly(methyl methacrylate) (PMMA) (2 wt%−10 wt%) was incorporated into the PLLA/carbon nanotubes (CNTs) composites. The effects of PMMA content on the dispersion of CNTs as well as the microstructure and hydrolytic degradation behaviors of the composites were systematically investigated. The results showed that PMMA promoted the dispersion of CNTs in the composites. Amorphous PLLA was obtained in all the composites. Largely enhanced hydrolytic degradation resistance was achieved by incorporating PMMA, especially at relatively high PMMA content. Incorporating 10 wt% PMMA led to a dramatic decrease in the hydrolytic degradation rate from 0.19 %/h of the PLLA/CNT composite sample to 0.059 %/h of the PLLA/PMMA-10/CNT composite sample. The microstructure evolution of the composites was also detected, and the results showed that no crystallization occurred in the PLLA matrix. Further results based on the interfacial tension calculation showed that the enhanced hydrolytic degradation resistance of the PLLA matrix was mainly attributed to the relatively strong interfacial affinity between PMMA and CNTs, which prevented the occurrence of hydrolytic degradation at the interface between PLLA and CNTs. This work provides an alternative method for tailoring the hydrolytic degradation ability of the PLLA-based composites.
Corrected proof , doi: 10.1007/s10118-019-2314-0
[Abstract](263) [FullText HTML](9) [PDF 324KB](5)
Abstract:
Liquid-liquid (L-L) de-mixing and vitrification of solutions of either crystallizable poly(L-lactic acid) (PLLA) or non-crystallizable poly(D/L-lactic acid) (PDLLA) with 50 m% N,N-diethyl-3-methylbenzamide (DEET) were analyzed by calorimetry and cloud-point measurements, which allows drawing conclusions about the effect of polymer stereochemistry on the phase behavior. Regardless of the PLA stereochemistry, vitrification of the solutions on fast cooling, hindering crystallization of PLLA, occurred below −20 °C and suppressed prior L-L de-mixing. The experimental results prove that crystallization in samples containing crystallizable PLLA, observed at around 55 °C on slow cooling, is not preceded by L-L de-mixing.
Corrected proof , doi: 10.1007/s10118-019-2307-z
[Abstract](282) [FullText HTML](12) [PDF 412KB](23)
Abstract:
In this study, two new dendronized nonlinear optical (NLO) polymers were synthesized with high FTC chromophore loading density by introduction of high generation chromophore dendrons on the side chains. Due to their suitable molecular weights, both of them possessed good solubility in common solvents. They also inherited the advantages of dendrimers (large NLO coefficient), especially for PG2 whose NLO coefficient d33 value was as high as 282 pm·V–1. Also, PG2 had a good temporal stability with 80% of its maximum value being retained at the temperature as high as 129 °C.
Corrected proof , doi: 10.1007/s10118-019-2303-3
[Abstract](269) [FullText HTML](11) [PDF 1556KB](11)
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Polymerization-induced self-assembly (PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast majority of emulsion PISA formulations using insoluble monomers leads to kinetically-trapped spheres. Herein, we present aqueous emulsion PISA formulations generating worms and vesicles besides spheres. Two monomers with different butyl groups, n-butyl (nBHMA) and tert-butyl (tBHMA) α-hydroxymethyl acrylate, and thus possessing different water solubilities were synthesized via Baylis-Hillman reaction. Photoinitiated aqueous emulsion polymerizations of nBHMA and tBHMA employing poly(ethylene glycol) macromolecular chain transfer agents (macro-CTAs, PEG45-CTA, and PEG113-CTA) at 40 °C were systematically investigated to evaluate the effect of monomer structure and solubility on the morphology of the generated block copolymer nano-objects. Higher order morphologies including worms and vesicles were readily accessed for tBHMA, which has a higher water solubility than that of nBHMA. This study proves that plasticization of the core-forming block by water plays a key role in enhancing chain mobility required for morphological transition in emulsion PISA.
Corrected proof , doi: 10.1007/s10118-020-2340-y
[Abstract](173) [FullText HTML](8) [PDF 553KB](13)
Abstract:
Ion segregation is critically important for achieving high ion conductivity for anion exchange membranes (AEMs). Herein, a new bisphenol monomer bearing ten electron-rich phenyl groups was designed and polymerized with various amounts of electron-deficient 4,4′-dihydroxydiphenylsulfone and 4,4′-difluorobenzophenone to yield dense and selective reaction sites for chloromethylation and quaternization. As the most challenging step, chloromethylation was optimized by tuning the reaction temperature, reaction time, and reactant ratios. Ion exchange capacity, water uptake, anion conductivity, mechanical stability, and alkaline stability of the resulting AEMs were characterized in detail. It is found that chloromethylation reaction needed to be carried out at low equivalent of chloromethylation agents to avoid undesirable crosslinking. The QA-PAEKS-20 sample with an IEC of 1.19 mmol·g−1 exhibited a Cl conductivity of 11.2 mS·cm−1 and a water uptake of 30.2% at 80 °C, which are promising for AEM applications.
Corrected proof , doi: 10.1007/s10118-020-2364-3
[Abstract](65) [FullText HTML](10) [PDF 802KB](1)
Abstract:
In this work, step-cycle tensile behavior of two bimodal polyethylene (PE) materials, a PE100 grade pipe material, XS10, and a PE100-RC (Resistant Crack) grade pipe material, XSC50, was comparatively investigated. By decomposing the strain into a recoverable part and an unrecoverable part, it was found that the deformation recovery capability of XSC50 during stretching was larger than that of XS10. Structural evolution characterized by in situ synchrotron small angle X-ray scattering indicated that the fragmentation of initial crystals in XSC50 occurred at lower strain than in XS10. Considering that XSC50 had relatively small lamellar thickness and similar crystallinity to XS10, we speculated that the larger deformation recovery capability of XSC50 during stretching probably derived from stronger entangled amorphous region caused by larger density of tie molecules and entanglements, which were usually regarded to have a significant influence on the slow crack growth (SCG) resistance of PE materials. As expected, the experimental result of strain hardening modulus test suggested that the deformation recovery capability during stretching was positively correlated with the SCG resistance for XS10 and XSC50 used in this work. The step-cycle tensile test had the potential to be developed into a supplement for comparison of SCG resistance of PE materials.
Corrected proof , doi: 10.1007/s10118-020-2365-2
[Abstract](68) [FullText HTML](12) [PDF 1196KB](0)
Abstract:
As a typical plant virus which has biocompatibility and high transfection efficiency, tobacco mosaic virus (TMV) has shown broad application potential in drug or gene delivery field. Elucidating its intracellular trafficking is of great importance in investigation of its cytotoxicity, targeting site, and delivery efficiency, and is advantageous to designing new TMV-based drug delivery systems with different targets. By taking advantage of the regulated pH value of different organelles in a mammalian cell, we exploit a pH detection strategy to investigate the intracellular trafficking pathway of TMV. Here, we report a single-wavelength excited ratiometric fluorescent pH probe. This probe is constructed by simultaneously coupling pH-sensitive fluorescein isothiocyanate (FITC) and pH-insensitive rhodamine B isothiocyanate (RBIRC) onto the inner surface of TMV. The fluorescence intensity ratio of FITC to RBITC excited at 488 nm responds specifically towards pH value over other interferential agents. By taking use of this single-wavelength excited ratiometric pH probe and confocal laser scanning microscopy, it is shown that the endocytosed TMV is located in a pH decreasing microenvironment and eventually enters lysosomes. This work may provide important guidance on construction of TMV-based nano carriers.
Corrected proof , doi: 10.1007/s10118-020-2363-4
[Abstract](57) [FullText HTML](15) [PDF 6239KB](1)
Abstract:
The role of mold temperature on the morphology and properties of rotational shearing polyethylene (PE) pipes was studied via a self-developed rotational shear system (RSS). The result indicated that when the mold temperature was 150 °C, the hoop tensile strength and Vicat softening temperature were enhanced rapidly, which were 383.6% and 137.9% higher than those of the conventional PE pipes, respectively. Morphology and crystal structure studies by SEM and DSC revealed that once the rotational shear was applied, the shish-kebab structure began to appear. With the increase of the mold temperature, due to the relaxation of most of the oriented molecular chains, the preservation of shish-kebab structure became difficult. When the mold temperature was 190 °C, only the inner layer of the pipes, where the cooling rate was the largest, could preserve the shish-kebab structure. According to WAXD, there was less shish structure, and the growth of kebab was distorted in the inner layer of the pipes at 210 °C. The result of SAXS suggested that the length of shish changed most within the temperature range from 170 °C to 190 °C. The results of DSC and WAXD showed less change in crystallinity and degree of orientation between the two temperatures. It can be concluded that the reduction of shish length leads to a decrease in mechanical properties and heat-resistance.
Corrected proof , doi: 10.1007/s10118-020-2352-7
[Abstract](131) [FullText HTML](31) [PDF 1485KB](18)
Abstract:
In this study, we investigate the motion of polymer segments in polymer/nanoparticle composites by varying nanoparticle (NP) volume fractions. By studying the probability distribution of segment displacement, segment trajectory, and the square displacement of segment, we find the intermittent motion of segments, accompanied with the coexistence of slow and fast segments in polymer nanocomposites (PNCs). The displacement distribution of segments exhibits an exponential tail, rather than a Gaussian form. The intermittent dynamics of chain segments is comprised of a long-range jump motion and a short-range localized motion, which is mediated by the weakly attractive interaction between NP and chain segment and the strong confinement induced by NPs. Meanwhile, the intermittent motion of chain segments can be described by the adsorption-desorption transition at low particle loading and confinement effect at high particle loading. These findings may provide important information for understanding the anomalous motion of polymer chains in the presence of NPs.
Corrected proof , doi: 10.1007/s10118-020-2367-0
[Abstract](66) [FullText HTML](22) [PDF 649KB](2)
Abstract:
Mechanistic transformation approach has been widely applied in polymer synthesis due to its unique feature combining structurally different polymers prepared by different polymerization mechanisms. Reported methods for the formation of block and graft copolymers through mechanistic transformation involve almost all polymerizations modes. However, certain polymerization processes require extensive purification processes, which can be time-consuming and problematic. Recent developments on controlled/living polymerizations involving radical and cationic mechanisms with the ability to control molecular weight and functionality led to new pathways for mechanistic transformations. In this mini-review, we systematically discussed relevant advances in the field through three main titles namely (i) from radical to cationic mechanism, (ii) from cationic to radical mechanism, and (iii) application of specific catalyst systems for both radical and cationic polymerizations.
Corrected proof , doi: 10.1007/s10118-020-2362-5
[Abstract](114) [FullText HTML](30) [PDF 548KB](5)
Abstract:
The microstructural development of bimodal high density polyethylene subjected to tensile deformation was investigated as a function of strain after annealing at different temperatures by means of a scanning synchrotron small angle X-ray scattering (SAXS) technique. Two different deformation mechanisms were activated in sequence upon tensile deformation: intralamellar slipping of crystalline blocks dominates the deformation behavior at small deformations whereas a stress-induced crystalline block fragmentation and recrystallization process occurs at a critical strain yielding new crystallites with the molecular chains preferentially oriented along the drawing direction. The critical strain associated with the lamellar-to-fibrillar transition was found to be ca. 0.9 in bimodal sample, which is significantly larger than that observed for unimodal high-density polyethylene (0.4). This observation is primarily due to the fact that the bimodal sample possesses a greater mobility of the amorphous phase and thereby a reduced modulus of the entangled amorphous network. The conclusion of the mobility of the amorphous phase as a determining factor for the critical strain was further proven by the 1H-NMR T2 relaxation time. All these findings contribute to our understanding of the excellent slow crack growth resistance of bimodal polyethylene for pipe application.
Corrected proof , doi: 10.1007/s10118-020-2359-0
[Abstract](134) [FullText HTML](12) [PDF 331KB](5)
Abstract:
A series of new bisphosphine-monoxide (BPMO) ligands based on benzothiophene backbone and the corresponding palladium complexes {к2-2-P(O)(Ph)2-3-PR1R2-C8H4S}PdMeCl { 2a : R1 = R2 = Ph; 2b : R1 = R2 = 2-OMe-Ph; 2c : R1 = R2 = 2-CF3-Ph; 2d : R1 = Ph, R2 = 2-(2′,6′-(OMe)2C6H3)-C6H4} were synthesized and fully characterized by 1H-, 13C-, 31P-, and 2D-NMR spectroscopy and single-crystal X-ray diffraction. In the presence of Na+B[3,5-(CF3)2C6H3]4 (NaBArF), these complexes showed very high activities (up to 2.0 × 107 g·mol–1·h–1) for ethylene polymerization. More significantly, these catalysts enabled the copolymerization of ethylene with a broad scope of commercially available polar comonomers such as acrylates, acrylic acid, acrylonitrile, vinyltrialkoxysilane, allyl acetate, and long-chain 6-chloro-1-hexene to give functionalized polyethylene with reasonable catalytic activities (up to 106 g·mol–1·h–1) and incorporations (up to 5.3 mol%). This contribution suggests that, besides the modulation of conventionally steric and electronic factors, the connectivity (at different linking positions) of BPMO (P,O) donors to the heteroaryl backbone also greatly influences the catalyst properties in terms of catalytic activity, polymer branching content, comonomer scope, and comonomer incorporation.
Corrected proof , doi: 10.1007/s10118-020-2356-3
[Abstract](157) [FullText HTML](16) [PDF 439KB](18)
Abstract:
Advances in organic photovoltaic technologies have been geared toward industrial high-throughput printing manufacturing, which requires insensitivity of photovoltaic performance regarding to the light-harvesting layer thickness. However, the thickness of light-harvesting layer for all polymer solar cells (all-PSCs) is often limited to about 100 nm due to the dramatically decreased fill factor upon increasing film thickness, which hampers the light harvesting capability to increase the power conversion efficiency, and is unfavorable for fabricating large-area devices. Here we demonstrate that by tuning the bulk heterojunction morphology using a non-halogenated solvent, cyclopentyl methyl ether, in the presence of a green solvent additive of dibenzyl ether, the power conversion efficiency of all-PSCs with photoactive layer thicknesses of over 500 nm reached an impressively high value of 9%. The generic applicability of this green solvent additive to boost the power conversion efficiency of thick-film devices is also validated in various bulk heterojunction active layer systems, thus representing a promising approach for the fabrication of all-PSCs toward industrial production, as well as further commercialization.
Corrected proof , doi: 10.1007/s10118-020-2361-6
[Abstract](87) [FullText HTML](13) [PDF 1180KB](6)
Abstract:
In this study, the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide) (PDLA-b-PBS-b-PDLA) triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized, and the crystallization behaviors of the PDLA and PBS blocks are investigated. Although both the crystallization behaviors of PBS and PDLA blocks depend on composition, they exhibit different variations. For the PDLA block, its crystallization behaviors are mainly influenced by temperature and block length. The crystallization signals of PDLA block appear in the B-D 2-2 specimen, and these signals get enhanced with PDLA block length. The crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100 °C. Crystallizing at higher temperature, the crystallization rates increase at first and then decrease with block length. The crystallization rates decrease as elevating the crystallization temperature. The melting temperatures of PDLA blocks increase with block lengths and crystallization temperatures. For the PBS block, its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA block. The crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized, while the crystallization rates of the PBS block exhibit unique component dependence, and the highest rate is observed in the B-D 2-2 specimen. The Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher temperature. This investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.
Corrected proof , doi: 10.1007/s10118-020-2343-8
[Abstract](246) [FullText HTML](31) [PDF 341KB](9)
Abstract:
Using a hybrid simulation approach that combines a finite difference method with a Brownian dynamics, we investigated the motion of charged polymers. Owing to the fact that polymer-solution systems often contain a large number of particles and the charged polymer chains are in a state of random motion, it is a time-consuming task to calculate the electrostatic interaction of the system. Accordingly, we propose a new strategy to shorten the CPU time by reducing the iteration area. Our simulation results illustrate the effect of preset parameters on CPU time and accuracy, and demonstrate the feasibility of the " local iteration” method. Importantly, we find that the increase in the number of charged beads has no significant influence on the time of global iterations and local iterations. For a number of 80 × 80 × 80 grids, when the relative error is controlled below 1.5%, the computational efficiency is increased by 8.7 times in the case that contains 500 charged beads. In addition, for a number of 100 × 100 × 100 grids with 100 charged beads, the computational efficiency can be increased up to 12 times. Our work provides new insights for the optimization of iterative algorithms in special problems.
Corrected proof , doi: 10.1007/s10118-020-2358-1
[Abstract](256) [FullText HTML](123) [PDF 428KB](16)
Abstract:
Eight 6FDA-TFDB polyimide (PI) samples with absolute molecular weights ranging from 1.25 × 105 g·mol–1 to 3.11 × 105 g·mol–1 are obtained by precipitation fractionation. Rheological experiments are conducted to determine the influence of molecular weight on the associating behavior of PI in N,N′-dimethylformamide (DMF) solutions in a broad volume fraction, including abnormal steady shear flow, solution heterogeneity, and scaling behavior. Abnormal flow behaviors, i.e., multi-region shear thinning and weak shear thickening, are studied, and these behaviors have not been reported in literature. The heterogeneity of PI/DMF solutions is examined by dynamic rheological test. By plotting ηsp versus ϕ/ϕη, four concentration regions of I–IV can be distinguished for all PI samples with various molecular weights. The scaling results in different concentration regions are in good agreement with the associative polymer theory proposed by Rubinstein and Semenov. The scaling exponents do not show molecular weight dependence in concentration regions I and II. In concentration regions III and IV, the scaling exponents change little when the molecular weight is below 242 k but increase when the molecular weight increases from 242 k to 311 k. This work can help us to understand polyimide solution properties from dilute to semidilute entangled solutions, and will guide the polyimide solution preparation for different processing.
Corrected proof , doi: 10.1007/s10118-020-2354-5
[Abstract](157) [FullText HTML](45) [PDF 1497KB](7)
Abstract:
Poly(butylene 2,6-naphthalate) (PBN) is a crystallizable linear polyester containing a rigid naphthalene unit and flexible methylene spacer in the chemical repeat unit. Polymeric materials made of PBN exhibit excellent anti-abrasion and low friction properties, superior chemical resistance, and outstanding gas barrier characteristics. Many of the properties rely on the presence of crystals and the formation of a semicrystalline morphology. To develop specific crystal structures and morphologies during cooling the melt, precise information about the melt-crystallization process is required. This review article summarizes the current knowledge about the temperature-controlled crystal polymorphism of PBN. At rather low supercooling of the melt, with decreasing crystallization temperature, β′- and α-crystals grow directly from the melt and organize in largely different spherulitic superstructures. Formation of α-crystals at high supercooling may also proceed via intermediate formation of a transient monotropic liquid crystalline structure, then yielding a non-spherulitic semicrystalline morphology. Crystallization of PBN is rather fast since its suppression requires cooling the melt at a rate higher than 6000 K·s−1. For this reason, investigation of the two-step crystallization process at low temperatures requires application of sophisticated experimental tools. These include temperature-resolved X-ray scattering techniques using fast detectors and synchrotron-based X-rays and fast scanning chip calorimetry. Fast scanning chip calorimetry allows freezing the transient liquid-crystalline structure before its conversion into α-crystals, by fast cooling to below its glass transition temperature. Subsequent analysis using polarized-light optical microscopy reveals its texture and X-ray scattering confirms the smectic arrangement of the mesogens. The combination of a large variety of experimental techniques allows obtaining a complete picture about crystallization of PBN in the entire range of melt-supercoolings down to the glass transition, including quantitative data about the crystallization kinetics, semicrystalline morphologies at the micrometer length scale, as well as nanoscale X-ray structure information.
Corrected proof , doi: 10.1007/s10118-020-2357-2
[Abstract](173) [FullText HTML](38) [PDF 759KB](12)
Abstract:
Human skin can function steadily regardless of surrounding circumstances (dry or wet), while it is still a challenge for artificial ionic skins, which tend to release solvents in dry air and leach electrolytes in wetted state. Herein, a series of hierarchically crosslinked ionogels containing hydrophobic ionic liquids (ILs) is fabricated by combining a crystalline fluorinated copolymer with hydrophobic ILs. With a reasonable combination of nonvolatility, transparency, stretchablility, and sensitivity, such ionogels can work as reliable sensors for real-time monitoring human motions and operate steadily in complex environments as human skin does, which can contribute to the development of durable sensing devices with a simple design.
Corrected proof , doi: 10.1007/s10118-020-2351-8
[Abstract](174) [FullText HTML](51) [PDF 1075KB](5)
Abstract:
A tetrahedral polyelectrolyte brush in the presence of trivalent counterions is researched under the condition of good solution by means of molecular dynamics simulations. Grafting density and charge fraction are varied to generate a series of surface patterns. Lateral microphase separation happens and various interesting pinned patches appear at appropriate charge fraction and grafting density. Through a careful analysis on the brush thickness, the pair correlation functions, the distributions of net charge, and the four states of trivalent counterions in the brush, we find that the ordered surface patterns and special properties are induced by the pure electrostatic correlation effect of trivalent ions even in the good solvent. Furthermore, the dependences of electrostatic correlation on the charge fraction of tethered chains are evaluated for fixed grafting density. Also, our results can serve as a guide for precise control over the stimuli-responsive materials rational and self-assembly of nanoparticles.
Corrected proof , doi: 10.1007/s10118-020-2336-7
[Abstract](273) [FullText HTML](52) [PDF 815KB](19)
Abstract:
Polyester (PET) was pre-activated by atmospheric air plasma and coated by various inorganic oxide nanoparticles (MOx) such as titanium dioxide (TiO2), zinc oxide (ZnO), and silicon oxide (SiO2), using poly(vinylidene fluoride) (PVDF) and chitosan (CT) as binders. The resulting PET-PVDF-MOx-CT composites were thermally compressed and then characterized by scanning electron microscopy, Fourier infrared spectroscopy, thermal gravimetric analysis, and flame retardancy (FR) ability tests. PET modifications resulted in more thermally stable and less harmful composites with weaker hazardous gas release. This was explained in terms of structure compaction that blocks pyrolysis gas emissions. CT incorporation was found to reduce the material susceptibility to oxidation. This judicious procedure also allowed improving flame retardancy ability, by lengthening the combustion delay and slowing the flame propagation. Chitosan also turned out to contribute to a possible synergy with the other polymers present in the synthesized materials. These results provide valuable data that allow understanding the FR phenomena and envisaging low-cost high FR materials from biodegradable raw materials.
Corrected proof , doi: 10.1007/s10118-020-2353-6
[Abstract](163) [FullText HTML](54) [PDF 947KB](10)
Abstract:
Aqueous zinc-ion batteries, especially Zn-MnO2 battery, have attracted intensive attention owing to their unique features of high capacity, environmental friendliness, and safety. However, the problem of Mn dissolution hinders the development of zinc-ion batteries with long-term usage and high-rate performance. In this work, a novel preparation method for the polyaniline (PANI)-coated composite aerogel of MnO2 and rGO (MnO2/rGO/PANI) electrode is reported. The obtained composite possesses high electrical conductivity, and also effectively suppresses the dissolution of Mn. The fabricated MnO2/rGO/PANI//Zn battery exhibits a high capacity of 241.1 mAh·g−1 at 0.1 A·g−1, and an excellent capacity retention of 82.7% after 600 charge/discharge cycles. In addition, the rapid diffusion coefficient of the MnO2/rGO/PANI electrode was further examined by galvanostatic intermittent titration technique. This work provides new insights into the development of high-performance Zn-MnO2 battery with a better understanding of its diffusion kinetics.
Corrected proof , doi: 10.1007/s10118-020-2348-3
[Abstract](80) [FullText HTML](40) [PDF 469KB](2)
Abstract:
Ethylene-propene copolymers have been synthesized by three C1-symmetric metallocene molecules ( 1 , 2 , and 3 ), having tert-butyl substituents on the Cp moiety, on the fluorenyl moiety, or on both moieties, and methylaluminoxane (MAO) at different polymerization temperatures and monomer concentrations. Copolymers were investigated by 13C-NMR, 1H-NMR, and SEC analyses. A relationship was found between [EEE]/[E] ratios and copolymer molar masses in each series: the higher the [EEE]/[E] ratio, the lower the copolymer molar mass. At parity of [EEE]/[E] ratio, copolymer molar mass follows the order 1 >> 3 > 2 . Chain end group analysis reveals that copolymers mainly terminate when propene is the last inserted unit, confirming that it is the greater facility of Mt-P-E-poly(E-co-P) to terminate that influences the copolymer molar mass. Among the catalysts considered, catalyst 1 , which gives syndiospecific polypropene, gives greater activities, comonomer incorporation, and molar masses. Catalyst 3 , which gives isospecific polypropene, in copolymerization performs better than 2 , having the same bridge, with respect to activities, ethylene content, and molar masses. The good performance of this catalyst arises from the not necessity of polymer chain to back skip when ethylene is the last inserted unit.
Corrected proof , doi: 10.1007/s10118-020-2349-2
[Abstract](360) [FullText HTML](46) [PDF 5683KB](12)
Abstract:
Poly(methyl methacrylate) (PMMA)/polystyrene (PS)/carbon black (CB) and poly(ethyl methacrylate) (PEMA)/PS/CB ternary composite films were obtained using solution casting technique to investigate double percolation effect. In both PMMA/PS/CB and PEMA/PS/CB ternary composite films, the CB particles prefer to locate into PS phase based on the results of calculating wetting coefficient, which is also confirmed by SEM images. The conductivity of the films was investigated, and the percolation threshold (ϕc) of both ternary composite films with different polymer blend ratios was determined by fitting the McLachlan GEM equation. Conductivity of PMMA/PS/CB ternary composite films showed a typical double percolation effect. However, due to the double emulsion structure of PEMA/PS polymer blends, the PEMA/PS/CB ternary composite films (PEMA/PS = 50/50) showed a higher ϕc, even CB only located in PS phase, which conflicts with the double percolation effect. A schematic diagram combined with SEM images was proposed to explain this phenomenon.
Corrected proof , doi: 10.1007/s10118-020-2346-5
[Abstract](248) [FullText HTML](78) [PDF 1662KB](20)
Abstract:
Stretching polymer in fluid flow is a vital process for studying and utilizing the physical properties of these molecules, such as DNA linearization in nanofluidic channels. We studied the role of hydrodynamic interactions (HIs) in stretching a free star polymer in Poiseuille flow through a tube using mesoscale hydrodynamic simulations. As increasing the flow strength, star polymers migrate toward the centerline of tube due to HIs, whereas toward the tube wall in the absence of HIs. By analyzing the end monomer distribution and the perturbed flow around the star polymer, we found that the polymer acts like a shield against the flow, leading to additional hydrodynamic drag forces that compress the arm chains in the front of the star center toward the tube axis and lift the arm chains at the back toward the tube wall. The balanced hydrodynamic forces freeze the polymer into a trumpet structure, where the arm chains maintain a steady strongly stretched state at high flow strength. In contrast, the polymer displays remarkably large conformational change when switching off HIs. Our simulation results explained the coupling between HIs and the structure of star polymers in Poiseuille flow.
Corrected proof , doi: 10.1007/s10118-020-2342-9
[Abstract](219) [FullText HTML](71) [PDF 449KB](18)
Abstract:
Two conjugated polymers (PuIDTBD and PuIDTQ) with unsymmetric side chains have been prepared for polymer solar cells using two other polymers (PIDTBD and PIDTQ) with symmetric side chains as control compounds. The combination of methyl and 4-hexylphenyl side chains on the same bridged carbon can ensure good solubility, decrease π-π stacking distances, and bring proper miscibility with PC71BM simultaneously. Therefore, the corresponding polymer solar cells (PSCs) based on donor polymers with unsymmetric side chains exhibited enhanced short-circuit current density (JSC) and power conversion efficiency (PCE) compared with those of control polymers. The PIDTBD and PIDTQ based devices possessed low PCE of 2.13% and 1.48%, while PCEs of devices based on PuIDTBD and PuIDTQ were improved to 3.93% and 4.12%, respectively. The results demonstrate that unsymmetric side chain engineering of conjugated polymers is an effective approach to achieve high performance PSCs.
Corrected proof , doi: 10.1007/s10118-020-2339-4
[Abstract](245) [FullText HTML](96) [PDF 425KB](19)
Abstract:
High-performance low-k and low-loss circuit materials are urgently needed in the field of microelectronics due to the upcoming Fifth-Generation Mobile Communications Technology (5G Technology). Herein, a facile design strategy for non-fluorinated intrinsic low-k and low-loss polyimides is reported by fully considering the secondary relaxation behaviors of the polymer chains. A new amorphous non-fluorinated polymer (TmBPPA) with a k value of 2.23 and a loss tangent lower than 3.94 × 10−3 at 104 Hz has been designed and synthesized, which to the best of our knowledge is the lowest value amongst the non-fluorinated and non-porous polymers reported in literature. Meanwhile, TmBPPA exhibits excellent overall properties, such as excellent thermostability, good mechanical properties, low moisture absorption, and high bonding strength. As high-performance flexible circuit materials, all these characteristics are highly expected to meet the present and future demands for high density, high speed, and high frequency electronic circuit used in 5G wireless networks.
Corrected proof , doi: 10.1007/s10118-020-2347-4
[Abstract](217) [FullText HTML](91) [PDF 1517KB](18)
Abstract:
In combination with methyllithium, a 2,6-bis(amino)phenol zinc complex 1 was used in the ring-opening polymerization of δ-valerolactone in the absence or presence of benzyl alcohol and showed high efficiency, mainly producing cyclic and linear polyvalerolactones, respectively. On the basis of homopolymerization, the ring-opening copolymerization of ε-caprolactone and δ-valerolactone was investigated. The P(CL-co-VL) random copolymers, PCL-b-PVL and PVL-b-PCL diblock copolymers, were prepared by varying the feeding strategy (premixing or sequential feeding). The copolymer composition was adjusted by varying the feeding ratio of two monomers. The structure and thermal properties of obtained polymers were characterized by GPC, 1H-NMR, 13C-NMR, MALDI-TOF mass spectroscopy, and DSC, respectively.
Corrected proof , doi: 10.1007/s10118-019-2332-y
[Abstract](252) [FullText HTML](89) [PDF 725KB](7)
Abstract:
Cross-linked polyamides (cPAs) were prepared through direct bulk Michael addition and subsequent polycondensation. Several mixed hexanediamine multi-esters (HDAMEs) were generated through the Michael addition of 1,6-hexanediamine (HDA) and methyl acrylate (MA) at 50 °C with different HDA/MA molar ratios. Melt polycondensation of HDAMEs then proceeded at 150 or 170 °C in flasks to obtain viscous fluids, and curing was continued in tetrafluoroethylene molds to obtain cPA films. The Michael addition was monitored on the basis of FTIR and ESI-MS spectra. The cPA films were characterized by DSC, TGA, dynamic mechanical analysis, and tensile test. These directly prepared cPAs exhibited Tg of 1–39 °C, tensile strength of up to 45 MPa, and strain at break from 18% to 40%. The cPAs with high tensile strength and good toughness were successfully synthesized through the direct bulk Michael addition from HDA and MA followed with polycondensation.
Corrected proof , doi: 10.1007/s10118-020-2344-7
[Abstract](186) [FullText HTML](85) [PDF 2386KB](8)
Abstract:
When a polymer is used together with others, its aging process will be affected by the adjacent polymers. This infectious behavior between polymers makes the aging process more complex than that of an individual material. In this study, infectious behavior in photo-oxidation of polymers was investigated. Polypropylenes (PPs), an unstabilized PP and a commercial PP, were chosen as the infection sources. Six typical polymers, high density polyethylene (HDPE), low density polyethylene (LDPE), polystyrene (PS), polycarbonate (PC), poly(ethylene terephthalate) (PET), and polyamide 6 (PA6), were used as the targets. The degree of oxidation of the targets was evaluated by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). An accelerating effect of two infection sources on the photo-oxidation of the target polymers was observed. Potential infectious agents from the infection sources were detected by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and gas chromatography (GC). The acceleration effect of two main infectious agents, i.e. acetone and acetic acid, on the photo-oxidation of the commercial PP was verified. The infectious effect of the infection source on the target polymer was considered to be a comprehensive result of the effects of a variety of infectious agents.
Corrected proof , doi: 10.1007/s10118-019-2322-0
[Abstract](262) [FullText HTML](73) [PDF 845KB](7)
Abstract:
We focus on the distribution and free energy of a wormlike polymer confined between two parallel hard walls. The variation in the distribution and free energy of the wormlike chain as the spacing between the walls decreases (or as the total contour length of the wormlike chain increases or as the persistence length of the chain increases) is simulated. The main reason for these changes is a degradation of the long wormlike chain into a Gaussian long chain under weak confinement.
Corrected proof , doi: 10.1007/s10118-020-2337-6
[Abstract](297) [FullText HTML](90) [PDF 1187KB](18)
Abstract:
For the solid-solid transformation from form II to form I of isotactic polybutene-1 (iPB), the temperature dependence of form I nucleation and growth was deemed to control the transformation process. However, the relationship between form I formation and form II disappearance in the transformation process is not clear. In this work, the spontaneous crystal transformation from form II to I of iPB with 81 mol% mmmm sequence concentration is studied firstly by tracking the two processes, the decay of form II and the yielding of form I in a wide range of temperature spanning from 0 °C to 50 °C and in a long transformation time ranging from 5 min to 65 days with in situ FTIR and WAXD. Unlike the literature reports, the decay rate of form II is firstly found to be lower than the yielding rate of form I at all studied temperatures, especially at low transition temperature. This is attributed to the amorphous chains which locate near crystal lamella participating into the nucleation of form II. The regular chain folding and growth of iPB form I from amorphous chains containing short isotactic sequences also lead to an increase in crystallinity of form I compared with that of initial form II crystallized at 60 °C. An increase in the annealing temperature results in decrease in crystallinity and increase in lamellae thickness of iPB form I.
Corrected proof , doi: 10.1007/s10118-019-2326-9
[Abstract](343) [FullText HTML](109) [PDF 469KB](8)
Abstract:
Intermolecular synergistic adsorption of indole and carbonyl groups induced by intermolecular hydrogen bonding makes microporous organic polymer (PTICBL) exhibit high CO2 uptake capacity (5.3 mmol·g−1 at 273 K) and selectivities (CO2/CH4 = 53, CO2/N2 = 107 at 273 K). In addition, we find that indole units in the PTICBL networks inhibit the attachment of bacteria (E. coil and S. aureus) on the surface of PTICBL and extend its service life in CO2 capture.
Corrected proof , doi: 10.1007/s10118-019-2321-1
[Abstract](343) [FullText HTML](94) [PDF 395KB](17)
Abstract:
Four truxene-based conjugated microporous polymers (Tr-CMPs) were prepared via different synthetic methods and their structure-property relationships were studied. The polymer networks have high Brunauer-Emmett-Teller (BET) specific surface areas ranging from 554 m2·g–1 to 1024 m2·g–1. Pore sizes of the CMPs with different linkers are mainly located between 0.60 and 1.96 nm. Among all the Tr-CMPs, Tr-CMP4 has the highest BET surface area of 1024 m2·g–1 and exhibits the highest H2 uptake of 0.88 wt%. Tr-CMP2 prepared by Suzuki-Miyaura coupling reaction has the highest photoluminescence quantum yields (PLQYs) of 13.06% and CO2 uptake of 6.25 wt%.
Corrected proof , doi: 10.1007/s10118-019-2305-1
[Abstract](428) [FullText HTML](209) [PDF 2078KB](16)
Abstract:
Researchers have put significant efforts on developing versatile fluorescent polymeric systems due to their promising biological/biomedical labelling, tracking, monitoring, imaging, and diagnostic applications. However, complicated organic/polymeric synthesis or post-modification of these functionalized platforms is still a big obstacle for their further application and thereby provides clear motivation for exploring alternative strategies for the design and fabrication of easily available fluorescent systems. The marriage of supramolecular polymers and fluorescent imaging can provide a facile and dynamic manner instead of tedious and time-consuming synthesis due to the dynamic and reversible nature of noncovalent interactions. Herein, based on water-soluble pillararene/paraquat molecular recognition, we successfully prepare two amphiphilic polypseudorotaxanes which can self-assemble into supramolecular polymersomes in water. These polymersomes can be reversibly destroyed and reformed by tuning the solution pH. Attributed to the aggregation-induced emission of tetraphenylethylene groups, intense fluorescence can be introduced into the obtained supramolecular polymersomes. Furthermore, pH-triggered release of an encapsulated water-insoluble drug (doxorubicin) from the self-assembled fluorescent supramolecular polymersomes is also investigated.
Corrected proof , doi: 10.1007/s10118-019-2324-y
[Abstract](333) [FullText HTML](213) [PDF 1010KB](4)
Abstract:
Dynamic control of mesenchymal stem cell (MSC) behaviors on biomaterial surface is critically involved in regulating the cell fate and tissue regeneration. Herein, a stimuli-responsive surface based on host-guest interaction with cell selectivity was developed to regulate migration of MSCs in situ by dynamic display of cell-specific peptides. Azobenzene-grafted MSC-affinitive peptides (EPLQLKM, Azo-E7) were grafted to β-cyclodextran (β-CD)-modified poly(2-hydroxyethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) (PHG) brushes, which were prepared by using surface-initiated atom transfer radical polymerization (SI-ATRP). X-ray photoelectron spectroscopy (XPS), quartz crystal microbalance (QCM), and water contact angle were used to characterize their structure and property. Cell adhesion assay showed that the combination effect of resisting property of PHG and MSC-affinity of E7 could promote the selective adhesion of MSCs over other types of cells such as RAW264.7 macrophages and NIH3T3 fibroblasts to some extent. UV-Vis spectroscopy proved that the competing guest molecules, amantadine hydrochloride (Ama), could release Azo-E7 peptides from the CD surface to different extents, and the effect was enhanced when UV irradiation was employed simultaneously. As a result, the decrease of cell adhesion density and migration rate could be achieved in situ. The cell density and migration rate could be reduced by over 40% by adding 20 μmol/L Ama, suggesting that this type of surface is a new platform for dynamic regulation of stem cell behaviors in situ.
Corrected proof , doi: 10.1007/s10118-019-2320-2
[Abstract](380) [FullText HTML](107) [PDF 5004KB](17)
Abstract:
In this work, the Hofmeister effects of nine kinds of anions at different concentrations on the lower critical solution temperature (LCST) of the macroporous thermo-responsive poly(N-isopropylacrylamide) grafted poly(vinyl alcohol) formaldehyde (PVF-g-PNIPAM) hydrogels are investigated with differential scanning calorimetry (DSC). Four kinds of anions with strong hydration, including CO32–, SO42–, S2O32–, and F, and four kinds of anions with weak hydration, including Br, NO3, I, and ClO4, and Cl as a medium anion are systematically studied and found to demonstrate the effects of the residual hydroxyl groups and network structure of PVF on the LCST values of PVF-g-PNIPAM hydrogels in comparison with that of neat PNIPAM. On the one hand, the existence of hydroxyl groups on PVF backbone promotes the solubility of grafted PNIPAM due to their hydrophilicity and hydrogen-bond interactions with water. On the other hand, the network structure of as-prepared samples restricts free movements of grafted PNIPAM chains, which results in the increase of LCST values. In addition, the difference of grafting percentage also influences the variation of LCST values of PVF-g-PNIPAM hydrogels under salt concentration.
Corrected proof , doi: 10.1007/s10118-019-2315-z
[Abstract](481) [FullText HTML](114) [PDF 1493KB](24)
Abstract:
Layer-by-layer polyelectrolyte self-assembly, a common method for preparing high-quality ultra-thin films, was employed to direct the self-assembly behavior of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) block copolymer for the first time. Differing from the previous neutral polymer brushes anchored to silicon substrates via chemical modification, polyelectrolyte multilayers (PEMs) were anchored by electrostatic interaction and provided a stable, smooth, and neutral interface. In the present study, PS-b-PMMA was deposited on poly(acrylamide hydrochloride)/poly(acrylic acid) (PAH/PAA) PEMs prepared by layer-by-layer self-assembly to successfully yield vertical nanodomains after thermal annealing. Seven layered PEMs revealed an excellent, smooth surface, with a low roughness of 0.6 nm. The periodic structure with interlamellar spacing of 47 nm was determined by grazing-incidence small-angle X-ray scattering (GISAXS). The morphology of the PS-b-PMMA nanodomains depended on the polyanion-to-polycation concentration ratio, which is related to the interaction between the block copolymer and the substrate. Our results demonstrate that layer-by-layer self-assembly is a helpful method for the phase separation of block polymers and the fabrication of vertical, ordered nanodomains.
Corrected proof , doi: 10.1007/s10118-019-2299-8
[Abstract](349) [FullText HTML](105) [PDF 1585KB](9)
Abstract:
Novel bio-based and biodegradable block copolymers were synthesized by " click” reaction between poly(L-lactide) (PLLA) and polyamide 4 (PA4). Upon tuning the molar mass of PLLA block, the properties of copolymers and electrospun ultrafine fibers were investigated and compared with those of PLLA and PA4 blends. PLLA and PA4 were found incompatible and formed individual crystalline regions, along with reciprocal inhibition in crystallization. Electrospun fibers were highly hydrophobic, even if hydrophilic PA4 was the rich component. The crystallinity of either PLLA or PA4 decreased after electrospinning and PLLA-rich as-spun fibers were almost amorphous. Immersion tests proved that fibers of block copolymers were relatively homogeneous with micro-phase separation between PLLA and PA4. The fibrous structures of copolymers were different from those of the fibers electrospun from blends, for which sheath-core structure induced by macro-phase separation between homopolymers of PLLA and PA4 was confirmed by TEM, EDS, and XPS.
Corrected proof , doi: 10.1007/s10118-019-2328-7
[Abstract](207) [FullText HTML](83) [PDF 923KB](13)
Abstract:
A series of Diels-Alder reaction cross-linked thermosets with recyclability and healability were prepared from furan-containing aromatic polyamide and bismaleimides with different chemical structures. The structures of synthesized bismaleimides were confirmed by 1H nuclear magnetic resonance (1H-NMR) spectroscopy; their reversible cross-linking with the furanic polyamide was further detected by 1H-NMR technique and sol-gel transition behavior. The dynamic mechanical analysis and tensile test revealed the variable thermal and mechanical properties of thermosets cross-linked by different bismaleimides and with different molar ratios of maleimide group to furan group (Ima/fur). The tensile test also demonstrated that the better recyclability and solvent-assisted healability of thermosets cross-linked could be achieved by more flexible bismaleimides. This work is expected to provide valuable information for design of recyclable and healable high-performance thermosets with desired properties.
Corrected proof , doi: 10.1007/s10118-019-2308-y
[Abstract](318) [FullText HTML](107) [PDF 336KB](16)
Abstract:
Poly(lactic acid) (PLA) is one of the most important bio-plastics, and chemical modification of the already-polymerized poly(lactic acid) chains may enable optimization of its material properties and expand its application areas. In this study, we demonstrated that poly(lactic acid) can be readily dissolved in acrylic acid at room temperature, and acrylic acid can be graft-polymerized onto poly(lactic acid) chains in solution with the help of photoinitiator benzophenone under 254 nm ultraviolet (UV) irradiation. Similar photo-grafting polymerization of acrylic acid (PAA) has only been studied before in the surface modification of polymer films. The graft ratio could be controlled by various reaction parameters, including irradiation time, benzophenone content, and monomer/polymer ratios. This photo-grafting reaction resulted in high graft ratio (graft ratio PAA/PLA up to 180%) without formation of homopolymers of acrylic acid. When the PAA/PLA graft ratio was higher than 100%, the resulting PLA-g-PAA polymer was found dispersible in water. The pros and cons of the photo-grafting reaction were also discussed.
Corrected proof , doi: 10.1007/s10118-019-2306-0
[Abstract](365) [FullText HTML](107) [PDF 1003KB](13)
Abstract:
In this study, novel electrochromic copolymers of 3,4-ethylenedioxythiophene (EDOT) and (E)-1,2-bis(2-fluoro-4-(4-hexylthiophen-2-yl)phenyl)diazene (M1) with different monomer feed ratios were designed and synthesized electrochemically. Electrochemical and spectroelectrochemical characterizations were performed using voltammetry and UV-Vis-NIR spectrophotometry techniques to test the applicability of copolymers for electrochromic applications. In terms of electrochemical behaviors, addition of an electron-rich EDOT unit into the azobenzene-containing copolymer increased the electron density on the polymer chain and afforded copolymers with very low oxidation potentials at around 0.30 V. While the homopolymers (P1 and PEDOT) exhibited neutral state absorptions centered at 510 and 583 nm, EDOT-bearing copolymers showed red shifted absorptions compared to those of P1 with narrower optical band gaps. In addition, the poor optical contrast and switching times of azobenzene-bearing homopolymer were significantly improved with EDOT addition into the copolymer chain. As a result of the promising electrochromic and kinetic preperties, CoP1.5-bearing single layer electrochromic device that works between purple and light greenish blue colors was constructed and characterized.
Corrected proof , doi: 10.1007/s10118-019-2317-x
[Abstract](414) [FullText HTML](132) [PDF 616KB](15)
Abstract:
One-component, catalyst-free self-healing coatings with double-shelled polymer microcapsules have drawn considerable attention due to wide applications. In this work, the synthesis parameters of double-shelled polymer microcapsules and the mechanism of the self-healing process were systematically investigated. Apart from the chemical structure of the microcapsule shell, the shell thickness, the microcapsule size, and the core fraction could affect the self-healing anticorrosion properties. The synthesis parameters were further optimized in terms of the agitation rate, pH, weight ratio of core to shell, and temperature. Under these conditions, the microcapsule shell consisting of a rough surface formed by poly(urea-formaldehyde) and a smooth inner wall by polyurethane was prepared. The size of the microcapsules and core fraction were calculated to be approximately 30 μm and 75%, respectively. The self-healing anticorrosion coating incorporating as-synthesized microcapsules exhibited corrosion resistance in artificially scratched areas, which was further characterized by electrochemical impedance spectroscopy.
Corrected proof , doi: 10.1007/s10118-019-2316-y
[Abstract](262) [FullText HTML](105) [PDF 333KB](24)
Abstract:
The copper-catalyzed and metal-free azide-alkyne click polymerizations have become efficient tools for polymer synthesis. However, the 1,3-dipolar polycycloadditions between internal alkynes and azides are rarely employed to construct functional polymers. Herein, the polycycloadditions of dibutynoate ( 1 ) and tetraphenylethene-containing diazides ( 2 ) were carried out at 100 °C for 12 h under solvent- and catalyst-free conditions, producing soluble poly(methyltriazolylcarboxylate)s (PMTCs) with high molecular weights in high yields. The resultant polymers were thermally stable with 5% weight loss temperatures up to 377 °C. The PMTCs showed aggregation-induced emission (AIE) properties. They could work as fluorescent sensors for detecting explosive with high sensitivity, and generate two-dimensional fluorescent photopatterns with high resolution. Furthermore, their triazolium salts could be utilized for cell-imaging applications.
Corrected proof , doi: 10.1007/s10118-019-2311-3
[Abstract](378) [FullText HTML](100) [PDF 613KB](26)
Abstract:
Vanillin was used as sustainable source for phthalonitrile monomer synthesis, and allyl/propargyl ether moieties were introduced to improve the processability at the minimal cost of thermal properties. The synthesis route was optimized to minimize side-reactions and simplify post-processing, and the monomers were obtained in high purity and good yields. The curing behavior, mechanism, and processability of the monomers were studied, and the thermal properties of cured polymers were evaluated. Of the two monomers, the allyl ether-containing one exhibited a wide processing window of 185 °C, and was mainly cured into phthalocyanine and linear aliphatic structures through self-catalytic curing process. Also, the glass transition temperature was higher than 500 °C. In contrast, the propargyl ether-containing monomer could only be partially cured, and heat resistance was found to be compromised. Compared with traditional petroleum-based phthalonitrile resins, the bio-based monomers could be cured without the addition of catalysts, and improvement in processability was achieved at no cost of thermal performances.
Corrected proof , doi: 10.1007/s10118-019-2302-4
[Abstract](301) [FullText HTML](104) [PDF 419KB](12)
Abstract:
The synthesis of a new azobenzene (azo)-containing main-chain crystalline polymer with reactive secondary amino groups in its backbone and photodeformation behaviors of its supramolecular hydrogen-bonded fibers are described. This main-chain azo polymer (namely Azo-MP6) was prepared via first the synthesis of a diacrylate-type azo monomer and its subsequent Michael addition copolymerization with trans-1,4-cyclohexanediamine under a mild reaction condition. Azo-MP6 was found to have a linear main-chain chemical structure instead of a branched one, as verified by comparing its 1H-NMR spectrum with that of the azo polymer prepared via the polymer analogous reaction of Azo-MP6 with acetic anhydride. The thermal stability, phase transition behavior, and photoresponsivity of Azo-MP6 were characterized with TGA, DSC, POM, XRD, and UV-Vis spectroscopy. The experimental results revealed that it had good thermal stability, low glass transition temperature, broad crystalline phase temperature range, and highly reversible photoresponsivity. Physically crosslinked supramolecular hydrogen-bonded fibers with good mechanical properties and a high alignment order of azo mesogens were readily fabricated from Azo-MP6 by using the simple melt spinning method, and they could show " reversible” photoinduced bending under the same UV light irradiation and good anti-fatigue properties.
Corrected proof , doi: 10.1007/s10118-019-2300-6
[Abstract](371) [FullText HTML](102) [PDF 1144KB](14)
Abstract:
How to control the spatial distribution of nanoparticles to meet different performance requirements is a constant challenge in the field of polymer nanocomposites. Current studies have been focused on the flexible polymer chain systems. In this study, the rigid polyimide (PI) chain grafted silica particles with different grafting chain lengths and grafting densities were prepared by " grafting to” method, and the influence of polymerization degree of grafted chains (N), matrix chains (P), and grafting density (σ) on the spatial distribution of nanoparticles in the PI matrix was explored. The glass transition temperature (Tg) of PI composites was systematically investigated as well. The results show that silica particles are well dispersed in polyamic acid composite systems, while aggregation and small clusters appear in PI nanocomposites after thermal imidization. Besides, the particle size has no impact on the spatial distribution of nanoparticles. When \begin{document}${ {\textit{σ}} \cdot {N^{0.5}} \ll {\left( {N/P} \right)^2}}$\end{document}, the grafted and matrix chains interpenetrate, and the frictional resistance of the segment increases, resulting in restricted relaxation kinetics and Tg increase of the PI composite system. In addition, smaller particle size and longer grafted chains are beneficial to improving Tg of composites. These results are all propitious to complete the microstructure control theory of nanocomposites and make a theoretical foundation for the high performance and multi-function of PI nanocomposites.
Corrected proof , doi: 10.1007/s10118-019-2293-1
[Abstract](470) [FullText HTML](171) [PDF 640KB](33)
Abstract:
Mechanochromic hydrogels, a new class of stimuli-responsive soft materials, have potential applications in a number of fields such as damage reporting and stress/strain sensing. We prepared a novel mechanochromic hydrogel using a strategy that has been developed to prepare dual-network (DN) hydrogels. A hydrophobic rhodamine derivative (Rh mechanophore) was covalently incorporated into a first network as a cross-linker. This first network embedded with Rh mechanophore within the DN hydrogel was pre-stretched. This guaranteed that the stress could be transferred extensively to the Rh-crosslinked first network once the hydrogel was under an applied force. Interestingly, we found that the threshold stress required to activate the mechanochromism of the hydrogel was less than 200 kPa, and much less than those in previous reports. Moreover, because of the excellent sensitivity of the hydrogel to stress, the DN hydrogel exhibited reversible freezing-induced mechanochromism. Benefiting from the sensitivity of Rh mechanophore to both pH and force, the DN hydrogel showed pH-regulated mechanochromic behavior. Our experimental results indicate that the preparation strategy we used introduces sensitive mechanochromism into the hydrogel and preserves the advantageous mechanical properties of the DN hydrogel. These results will be beneficial to the design and preparation of mechanochromic hydrogels with high stress sensitivity, and foster their practical applications in a number of fields such as damage reporting and stress/strain sensing.
Accepted Manuscript , doi: 10.1007/s10118-020-2375-0
[Abstract](27) [PDF 1132KB](0)
Abstract:
We employ finite element method to investigate the kinematics of non-axially positioned vesicles through a pore. To complete the coupling between fluid flow and the vesicle membranes, we use the fluid structure interactions with the arbitrary Lagrangian Eulerian method. Our results demonstrate that the vesicles show different deformations in migration process, in turn an oblique ellipse-shape, slipper-shape, oval-shape. We find that the rotation angle of non-axially positioned vesicles mainly shows the trend of increase, besides the small fluctuation induced by deformation relaxation. Moreover, when the vesicles move towards the axis of the channel, the rotation angle exhibits a decrease because of the decrease of the shear force. Whereas, axially positioned vesicles hardly occur rotation due to symmetrical shear force. Our results further indicate that the rotation velocity is the faster nearby the pore for non-axially positioned vesicles. Our work answers the mapping between the positions of the vesicles and deformed states, change of rotation angle and rotation velocity, which can provide helpful information on the utilization of vesicles in pharmaceutical, chemical, and physiological processes.
Accepted Manuscript , doi: 10.1007/s10118-020-2366-1
[Abstract](58) [PDF 1458KB](3)