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Abstract: In order to replace terpolymers with bipolymers, three bifunctional comonomers were synthesized to prepare poly(acrylonitrile-co-β-methylhydrogen itaconate) [P(AN-co-MHI)], poly(acrylonitrile-co-3-aminocarbonyl-3-butenoic acid methyl ester) [P(AN-co-ABM)] and poly(acrylonitrile-co-3-ammoniumcarboxylate-3-butenoic acid methyl ester) [P(AN-co-ACBM)] which can be used as carbon fiber precursor. The stabilization mechanism and effect of comonomer structure on the stabilization of bipolymers were studied by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetry. Two parameters and were defined to evaluate the extent of stabilization, and the activation energy (E a) of the cyclization reactions were calculated by Kissinger method and Ozawa method. The results show that P(AN-co-MHI), P(AN-co-ACBM) and P(AN-co-ABM) exhibit better stabilization than terpolymers containing similar chemical composition, such as lower initiation temperature, larger extent of stabilization and smaller E a. Furthermore, it is found that 3-ammoniumcarboxylate-3-butenoic acid methyl ester is the most effective one among the three comonomers for improving the stabilization of polyacrylonitrile (PAN) due to the strongest nucleophilicity of towards the carbon atom of adjacent nitrile groups. Simultaneously, the rheological analyses show that all the three bipolymers possess better spinnability than PAN homopolymer. [Copyright &y& Elsevier]

[Display omitted] • The developed atomistic model achieves Young's modulus prediction error of under 5% for mesophase pitch-based carbon fibers. • The diverse strengths of interactions among adjacent graphene nanoribbons lead to the emergence of distinct failure modes. • Active graphene edges strengthen the defective region, thus modifying load redistribution and improving structure strength. Mesophase pitch (MPP)-based carbon fibers exhibit outstanding mechanical properties, notably an exceptionally high Young's modulus. Despite extensive investigations into the microstructure of MPP-based carbon fibers, the influence of these factors on deformation mechanisms under tension remains unclear. This study employs the continuous defective graphene nanoribbons (dGNR) atomistic structure model for molecular dynamics simulations to explore the tensile failure mechanisms of MPP-based carbon fibers. In the simulation model, the structure of the defective region was generated through high-temperature annealing, and a transition region was introduced to prevent distortion and damage to the active graphene edges. The simulation reveals the evolutionary process of the microstructure of MPP-based carbon fibers under tension and achieves Young's modulus predictions with greater accuracy than theoretical models. Additionally, the study shows that different strengths of interactions between adjacent graphene nanoribbons can lead to two distinct failure modes. Models with larger crystallite dimensions along the fiber axis and lower average defective concentrations exhibit geometric deformation coordination between adjacent nanoribbons, potentially elucidating the increasing strength trend in MPP-based carbon fibers with rising graphitization levels. Our simulations provide insights into the tensile failure mechanisms of MPP-based carbon fibers, offering valuable guidance for regulating their microstructure to enhance mechanical performance. [ABSTRACT FROM AUTHOR]

Novel intelligent cellulose/4-vinyl-phenylboronic acid (VPBA) composite bio-hydrogels with glucose and pH-responsiveness were successfully prepared via electron beam irradiation technology at room temperature. The composites were characterized by Fourier transform infrared spectrum (FT-IR) and X-ray photoelectron spectroscopy (XPS). The electron beam irradiation results in the appearance of carbonyl in the polymerization of 4-ethenyl-phenylboronic acid, grafting and cross linking reaction in composites, and a novel composite hydrogel was formed between the poly-4-ethenyl-phenylboronic acid and cellulose matrix. By means of the incorporation of phenylboronic acid groups, the composite hydrogels with pH and glucose responsive properties was produced, and glucose responsive properties were investigated by the self-regulation of insulin release of composite hydrogel through a serial glucose solution with different concentrations, which is having great potential applications in many fields. [ABSTRACT FROM AUTHOR]

The Wingless-types/beta-catenin (Wnt/β-catenin) signaling pathway plays an important role in embryonic development and affects the physiological development processes of feather follicles. To investigate the role of Wnt/β-catenin pathway in regulating feather follicles morphogenesis, in ovo injection of CHIR-99021, an activator of the Wnt/β-catenin signaling pathway, was conducted in chick embryo model. Initially, a total of 40 embryos were used to assess feather follicles morphogenesis and the expression of β-catenin (E9–E17). The histological results showed that feather follicle morphogenesis was mainly completed from E9 to E17. β-catenin was involved in the processing of the appearance of dermal cell condensation (E9) and the completion of the feather follicles morphogenesis (E17). Next, a total of 160 fertilized eggs were randomly divided into 8 groups for in ovo injection at E9, including a Normal Saline injected group (CON) and the 500, 1,000, 2,000, 5,000, 10,000, 50,000, and 100,000 ng CHIR-99021 groups. Dorsal skin tissue samples were collected at E17 for investigating feather follicles morphology and expressions of β-catenin and lymphoid enhancerbinding factor-1 (LEF1) at gene and protein levels. The results showed that feather follicle diameter in the injected groups were significantly (P < 0.05) increased with limit dose-independence compared to the CON group. CHIR-99021 significantly (P < 0.05) influenced the mRNA expressions of catenin beta-1 ( CTNNB1 ) and downstream target LEF1. In ovo injection of CHIR-99021 caused that β-catenin and LEF1 were significantly (P < 0.05) increased followed the increased doses as determined by western blotting. The immunochemical results showed that β-catenin was detected in the dermal papilla of feather follicles. Given these results, this study suggests to developmental biology that in ovo injection of CHIR-99021 promoted feather follicles morphogenesis and development via activating Wnt/β-catenin signaling pathway and upregulating downstream target LEF1 during embryonic period in chick embryo model. Moreover, CHIR-99021 may be a strong candidate to promote the animal feather/hair industry, especially as a reference for bird feather production. [ABSTRACT FROM AUTHOR]