Although tremendous efforts have been devoted to the structural and functional tailoring of natural polyphenol-functionalized nanoparticles, preparing ultrasmall sized (< 6 nm) particles with precisely-defined structures has remained a grand challenge. In this work, we reported the preparation of ultra-small and precisely structured polyhedral oligomeric silsesquioxanes (POSS)-based polyphenol nanoparticles (T₈-, T₁₀-, and T₁₂-GAPOSS) by accurately functionalizing the POSS surface with plant polyphenol gallic acid units via thiol-Michael “click” reactions. Those polyphenol nanoparticles exhibited strong free radical scavenging capacity, good biocompatibility and ability to resist cell oxidative damage, which demonstrated great potentials in inhibiting oxidative stress induced pathologies.

Reducing the voltage loss (V_loss) is a critical factor in optimizing the open-circuit voltage (V_oc) and overall power-conversion efficiency (PCE) of polymer solar cells. In the current work, by designing a novel electron-accepting unit of coronenediimide (CDI) and using it as the main functional building block, a new polymer acceptor CDI-V is developed and applied to fabricate all-polymer solar cells. Compared with the perylenediimide-based polymer acceptors we previously reported, the current CDI-V polymer possesses a noticeably elevated lowest unoccupied molecular orbital (LUMO). Thereby, by virtue of the enlarged energy gap between the donor HOMO and acceptor LUMO, a high V_oc value of 1.05 V is achieved by the all-polymer photovolatic device, along with an impressively low V_loss of 0.55 V. As remarkably, in spite of an extremely small LUMO level offset of 0.01 eV exhibited by the donor and acceptor polymers, effective charge separation still takes place in the all-polymer device, as evidenced by a proper short-circuit current (J_sc) of 9.5 mA·cm⁻² and a decent PCE of 4.63%.

A series of thermoresponsive cationic dendronized copolymers and their corresponding nanogels containing dendritic oligoethylene glycol (OEG) units and guanidine groups were prepared, and their complexation, protection, and release of nucleic acids were investigated. The dendritic OEGs endow these copolymer materials with good biocompatibility and characteristic thermoresponsiveness, while cationic guanidine groups can efficiently bind with the nucleic acids. The dendritic topology also affords the copolymers specific shielding effect which plays an essential role in protecting the activity of nucleic acids. At room temperature, dendronized copolymers and the corresponding nanogels could efficiently capture and condense the nucleic acids, while above their cloud points (T_cps), more than 75% of siRNA could be released in 1 h triggered by ATP. More importantly, the copolymer showed protective capability to siRNA, while nanogels exhibit even better protection when compared to the copolymers due to the synergetic effect from the three-dimensional cross-linked network and high density of dendritic units in vicinity. This kind of smart dendronized copolymer nanogels form a novel class of scaffolds as promising materials for biomedical applications.

Azide-alkyne click polymerization has become a powerful tool for polymer synthesis. However, the click polymerization between internal alkynes and azides is rarely utilized to prepare functional polymers. In this work, the polymerization reactions of activated internal alkyne monomers of tris(2-butynoate)s (1) with tetraphenylethene-containing diazides (2) were performed in dimethylformamide (DMF) under simple heating, affording four hyperbranched poly(methyltriazolylcarboxylate)s (hb-PMTCs) with high molecular weights (M_w up to 2.4 × 10⁴) and regioregularities (up to 83.9%) in good yields. The hb-PMTCs are soluble in common organic solvents, and thermally stable with 5% weight loss temperatures up to 400 °C. They are non-emissive in dilute solution, but become highly emissive in aggregated state, exhibiting aggregation-induced emission characteristics. The polymers can generate fluorescent photopatterns with high resolution, and can work as fluorescent sensors to detect nitroaromatic explosive with high sensitivity.

The activation and deactivation of the chain-transfer agent were achieved by oxygen initiation and regulation with triethylborane under ambient temperature and atmosphere. The autoxidation of triethylborane overcame the oxygen inhibition and produced initiating radicals that selectively activate the chain-transfer agent for the chain growth or deactivate the active chain-end of polymer in controlled radical polymerization. Both activation and deactivation were highly efficient with broad scope for various polymers with different chain-transfer agents in both organic and aqueous systems. Oxygen molecule was particularly used as an external regulator to initiate and achieve the temporal control of both activation and deactivation by simply feeding the air.

Nanoporous polymer film with a hexagonal columnar (Col_h) structure was fabricated by templated hydrogen-bonding discotic liquid crystals containing methacrylate functional group. The supramolecular hydrogen-bonded complex T3Ph-L is composed of a 1,3,5-tris(1H-benzo[d]imidazol-2-yl)benzene (T3Ph) core molecule as the hydrogen-bonding acceptor and 3,4,5-tris((11-(methacryloyloxy)undecyl)oxy)benzoic acid (L) peripheral molecules as donors. And the Col_h structure is always retained after self-assembly, photo-crosslinking, and removal of the template T3Ph. The nanoporous polymer film can retain the Col_h phase even under the dry condition, which indicates more possibilities for practical applications. After chemical modification of the inner wall of the nanopores, the nanoporous polymer film with pores of about 1 nm selectively adsorbs ionic dyes, and the adsorption process is spontaneous and exothermic in nature. Homeotropic alignment can be obtained when the blend complex was sandwiched between two modified glasses after annealing by slow cooling, which shows that the nanoporous polymer film has potential in applications such as nanofiltration.

Stereoblock polypropylenes bearing isotactic, atactic, and syndiotactic polypropylene segments were successfully prepared by dry methyl aluminoxane activated binary catalysts system, Ph₂CFluCpZrCl₂ and {Me₂Si(2,5-Me₂-3-(2-MePh)-cyclopento[2,3-b]thiophen-6-yl)₂}ZrCl₂, in the presence of iBu₃Al as a chain shuttling agent. By studying the catalyst activity, chain transfer efficiency, and reversibility of chain transfer reaction of each catalyst system, as well as the molecular weight and polydispersity of the resulting polymers, the alkyl exchange reactions between the zirconium catalyst and different main-group metal alky were estimated, respectively. Based on the optimized react condition, the chain shuttling polymerization was conducted by binary catalyst system in the presence of iBu₃Al under both atmospheric and high pressure. Resultant polymers were identified as stereoblock polypropylenes according to microstructure and physical properties analyses by ¹³C{¹H}-NMR, DSC, and GPC.

This study aims to disclose the thermo-oxidative degradation behaviors and kinetics of a carbon fiber reinforced polyimide (CFRPI) composite for modeling of the long-term degradation process. The degradation behaviors were revealed through off-gas products analysis, and the overall kinetic interpretation was achieved from study of the mass-loss curves recorded under dynamic conditions. It was found that thermo-oxidative degradation of the CFRPI composite was a multistep process, which included four main reaction steps. Since most kinetic analysis methods were derived from simple reactions described by a single kinetic triplet, they cannot be applied reliably to such a process. Therefore, we firstly separated the four overlapped reaction steps by peak fitting of derivative thermogravimetric curves using Fraser-Suzuki equation considering the asymmetrical nature of kinetic curves, and subsequently analyzed each individual reaction employing Friedman method and experimental master-plots method. Four sets of kinetic triplets were determined to characterize the entire degradation process. The validity of four corresponding kinetic triplets was confirmed by perfect simulation of mass-loss curves recorded at both dynamic conditions used in kinetic analysis and entirely different isothermal conditions. Finally, modeling of long-term aging at 400 °C of the CFRPI composite was successfully achieved based on these kinetic triplets. The predicted mass loss and flexural property correlated well with experimental results. This study can serve as a basis for rapid evaluation of the long-term durability of the CFRPI composite in various application environments.

In order to promote the thermostability of α-diimine nickel complex by ligand backbone structure, a series of α-diimine nickel complexes with substituents on acenaphthequinone backbone were synthesized and used as catalysts for ethylene polymerization. When the hydroxyethyl phenoxyl group was introduced to the acenaphthequinone-backbone, the thermal stability and activity of the catalyst could be significantly improved. The catalytic activity of complex C2 [5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-diisopropyl)acenaphthylene-1,2-diimine]nickel(II) dibromide with isopropyl substituents on N-aryl reached 8.2 × 10⁶ g/(mol_Ni·h) at 70 °C and 2 MPa. The activity of [5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-dibenzhydryl-4-menthylphenyl)acenaphthylene-1,2-diimine]nickel(II) dibromide (C3) still maintained at 6.7 × 10⁵ g/(mol_Ni·h) at 120 °C. Compared with C3 containing bulky dibenzhydryl substituents, the activity of C2 was sensitive to the change of the polymerization pressure. However, the polyethylenes obtained from complex C3 had lower branching density. Meanwhile, the molecular weight could reach 971 kg/mol, which is almost 5 times as much as that of the polyethylene obtained from complex C2.

The design and fabrication of conductive hydrogels with high stretchability, compressibility, self-healing properties and good adhesion remains a significant challenge. We have fabricated composite hydrogels by random polymerization of acrylic acid (AA) and dopamine (DA) in the presence of multi-walled carbon nanotubes (MWCNTs). The π-π interaction between DA and MWCNTs makes MWCNTs stably and homogenously dispersed in water. The fabricated PAA-PDA/CNT composite hydrogels possess relatively high mechanical strength (maximum Young’s modulus: 800 kPa) and can be stretched to 1280% strain and compressed to 80% strain. The multiple hydrogen bonding formed between functional groups of PAA-PDA and MWCNTs can effectively dissipate energy and quickly achieve self-healing. The composite hydrogels also show good adhesion and can easily adhere to various inorganic or organic surfaces. In addition, the hydrogel reveals stable strain sensitivity and can be used as skin sensors.

The demand for high thermal stability and high strength agents is growing steadily as a result of their increasing application in advanced materials. A series of sulfonated poly(m-phenyleneisophthalamide) (SPMIA) copolymers with superior thermal stability and good mechanical properties have been prepared via low temperature polycondensation method. Then the structures of SPMIA copolymers with different content quantities of 2,4-diaminobenzenesulfonic acid (2,4-DABSA) were confirmed by Fourier transform infrared (FTIR). Besides, their superior thermal properties were systematically investigated by differential scanning calorimetry (DSC), thermalgravimetreic analysis (TGA), and dynamic mechanical analysis (DMA). SPMIA fibers were obtained by wet spinning using the resultant SPMIA solutions. In addition, the obtained SPMIA fibers were proved to combine enhanced mechanical properties and unprecedented dyeability. Significantly, the SPMIA fiber with great mechanical property, thermal stability, and dyeability shows great potential in easily dyeing high-performance protective fibers.

Electrospun poly(vinylidene fluoride) (PVDF) nanofiber web has been widely utilized as a functional material in various flexible sensors and generators due to its high piezoelectricity, ease processability, and low cost. Among all the crystalline phases of PVDF, β-phase is a key property for PVDF nanofiber web, because the content of β-phase is directly proportional to piezoelectric performance of PVDF nanofiber web. Herein, the impact of graphene content (GC), tip-to-collector distance (TCD), and rotational speed of collector (RSC), as well as their interactions on the β-phase formation of PVDF nanofiber web is systematically investigated via design of experimental method. The fraction of each crystalline phase of PVDF nanofiber web is calculated by FTIR spectra, and the crystallinity is determined by XRD patterns. The influences of GC, TCD, and RSC on both β-phase fraction and crystallinity of PVDF nanofiber are analyzed using Minitab program. The results show that GC, TCD, and RSC all have significant effect on the β-phase content of PVDF nanofiber web, and GC is the most significant one. In addition, an optimal electrospinning condition (GC = 1 wt%, TCD = 4 cm, and RSC = 2000 r·min^–1) to fabricate high β-phase crystallinity of PVDF nanofiber web is drawn, under which the crystallinity can reach 41.7%. The contributions in this study could provide guidance for future research on fabricating high performance PVDF nanofiber web based sensors or generators.

In this work, the formation of cocontinuous structure in immiscible high density polyethylene/isotactic polypropylene (HDPE/iPP) blends was investigated for various olefin-based compatibilizers of distinct molecular architectures, including ternary random copolymer EPDM, olefin block copolymer (OBC), polypropylene-based OBC (PP-OBC), ethylene/α-olefin copolymer (POE), bottlebrush polymer poly(1-dodecene), and comb-like poly(propylene-co-high α-olefin) (PPO). The scanning electron microscopy results show that after adding OBC, PP-OBC, and POE copolymers, the finer droplet-in-matrix morphologies were obtained in 70/30 HDPE/iPP blend. Interestingly, for 70/30 HDPE/iPP blend with just 5 wt% of PPO copolymers, the phase inversion from droplet-in-matrix to cocontinuous morphology can be observed. It was proposed that the development of cocontinuous morphology contained the following steps: (1) interfacial saturation of compatibilizers and droplet deformation, (2) droplet-droplet coalescence, (3) continuity development, and (4) the formation of dual-phase continuity. Among the diverse copolymers studied in this work, PPO copolymer can be easily removed out of the interface during droplet coalescence and stabilize the curvature of minor fiber phase, facilitating the formation of cocontinuous morphology. In contrast, other olefin-based compatibilizers (EPDM, OBC, PP-OBC, and POE) exhibit the distinct steric repulsion effect to prohibit droplet coalescence. Moreover, the cocontinous interval varies with the compatibilizer architectures. Surprisingly, after adding 10 wt% of PPO copolymers, the cocontinuous interval was greatly broadened from HDPE/iPP range of 45/55−60/40 to that of 40/60−70/30.

Low dielectric interlayer films have become an important element to ensure the development of the microelectronics industry. A kind of flexible interlayer dielectrics, polyarylene ether nitrile/bisphenol A cyanate ester (PEN/BADCy) film, with good thermal stability and low frequency dependence, has been developed by solution casting method. Herein, materials were designed to incorporate bisphenol A cyanate ester as a part of blend, contributing to the frequency stability and structural integrity. The morphological study combined with electron microscopy revealed the uniform and flexible microstructure information with controllable morphology through self-polymerization of cyanate esters with different prepolymerization time and curing temperatures. The dielectric films could present high thermal stability with T_g > 180 °C. Significant improvement in the dielectric properties was achieved for the dielectric constant and loss was much stabler than neat PEN over the frequency range from 100 Hz to 5 MHz. When the prepolymerization time was 3 h and final curing temperature reached 230 °C, the dielectric constant and dielectric loss of the films were 3.36 and 0.013 at 100 kHz, respectively. The dimensional stability (CTE = 53.67 × 10⁻⁶ K⁻¹) was confirmed and considered beneficial to use as an interlayer dielectrics.

Sustainable blends of poly(propylene carbonate) (PPC) and stereocomplex polylactide (sc-PLA) were prepared by melt blending equimolar poly(L-lactic acid) (PLLA) and poly(D-lactide acid) (PDLA) with PPC to form sc-PLA crystals in situ in the melt blending process. Differential scanning calorimetry analysis revealed that only sc-PLA, no homo-crystallization of PLLA or PDLA, formed in the PPC matrix as the sc-PLA content was more than 10 wt%. Very intriguingly, scanning electronic microscopy observation showed that sc-PLA was evenly dispersed in the PPC phase as spherical particles and the sizes of sc-PLA particles did not obviously increase with increasing sc-PLA content. As a consequence, the rheological properties of PPC were greatly improved by incorporation of sc-PLA. When the sc-PLA content was 20 wt%, a percolation network structure was formed, and the blends showed solid-like behavior. The sc-PLA particles could reinforce the PPC matrix, especially at a temperature above the glass transition temperature of PPC. Moreover, the Vicat softening temperature of PPC/sc-PLA blends could be increased compared with that of neat PPC.