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Highly reactive polyols were prepared from modified acetic acid lignin (AAL) by a two‐step combination of mild hydrothermal degradation and hydroxylation. The AAL‐based polyols became relatively reactive and compatible with diisocyanate, with a reduction in the number average molecular weight (Mn) from 2923 to 684 g/mol and an increase in the hydroxyl content from 5.21 to 9.13 mmol/g. The mechanical performance and thermal properties of the AAL‐based polyurethane elastomers (LPUEs) strongly depended on the molecular weight and hydroxyl content of the AAL‐based polyols in the partial substitution of polytetramethylethylene ether glycol (PTMEG). This study proposed the prospective utilization of AAL as an alternative resource in the synthesis of polymers and biomaterials. © 2021 Society of Industrial Chemistry and John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

A facile and cost-effective method to prepare poly(methyl methacrylate) (PMMA)/graphene oxide (GO) nanocomposites was developed byin situpolymerization. By using thermal-initiated and GO-initiated polymerization of methyl methacrylate (MMA), no extra radical initiator was added during the reaction. Without any pre-functionalization of GO, PMMA chains were covalently bonded to its surface, which was confirmed by Fourier-transform infrared, atomic force microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy investigations. TGA analysis showed that the mass ratio of grafted PMMA and GO was as high as 1.7. Transmission electron microscopy and X-ray powder diffraction investigations demonstrated that the grafting of PMMA chains to GO surfaces resulted in homogeneous dispersion of GO sheets in PMMA matrix, which led to a commendable performance on its mechanical and thermal properties. Dynamic mechanical analysis showed that, at a loading level of just 0.5 wt% for the nanocomposites, the storage modulus of the nanocomposites was improved 14%, and the glass transition temperature was increased 12°C in comparison with that of neat PMMA. Thermogravimetric analysis showed that the onset degradation temperature of the nanocomposites was increased 13°C with a GO content of 0.25 wt%. [ABSTRACT FROM AUTHOR]

Poly(p-phenylene benzobisoxazole)/poly(pyridobisimidazole) block copolymers (PBO-b-PIPD) were prepared by introducing poly(pyridobisimidazole) (PIPD) moieties into the main chains of poly(p-phenylene benzobisoxazole) (PBO) in order to enhance its photostability. PBO and copolymer fibers were directly prepared from the polymerization solutions by dry-jet wet-spinning. Chemical structures and molecular chains arrangement of the block copolymers were characterized by Fourier transform infrared (FTIR) spectroscopy, solid-state 13C-NMR and wide angle X-ray diffraction (WAXD). Thermal stability of the copolymers was investigated by thermogravimetric analysis (TGA) in nitrogen. Thin films of PBO and copolymers were cast from methanesulfonic acid (MSA) solutions. Both the films and fibers were exposed to UV light to determine their photostability. Changes in the chemical structures and surface morphologies of the films were characterized by FTIR spectra and scanning electronic microscopy (SEM), respectively. After UV light exposure, the retention of strength for copolymer fibers is improved compared to PBO fibers. The results revealed that copolymers suffered less photodegradation in comparison with homopolymer. The mechanism for the improved photostability of the copolymers was discussed. [ABSTRACT FROM PUBLISHER]

A series of high molecular weight poly(butylene-co-hexamethylene carbonate) (PBHC) copolycarbonates were synthesized by copolymerizations of dimethyl carbonate (DMC), 1,4-butanediol (BD) and 1,6-hexanediol (HD) via a two-step melt polycondensation method. Microstructure analysis determined by high-resolution 13C-NMR showed that butylene carbonate (BC) units and hexamethylene carbonate (HC) units of the synthesized copolymers take a random distribution along the polymer chains. Analyses of the formed byproducts indicated that sublimation of oligomer and thermal degradation of polymer happen during the aliphatic polycarbonate polycondensation. The thermal properties and crystalline structure of the copolymers were studied by DSC, TGA and WAXD. WAXD patterns showed that the copolymers with 11 and 91 mol% HC units form poly(butylene carbonate) (PBC) and poly(hexamethylene carbonate) (PHC) crystals, respectively, while the three other copolymers with intermediate HC unit contents are completely amorphous. The results indicated that the BC and HC units are incompatible in each crystal lattice, and that cocrystallization cannot take place. TGA results indicated that the thermal stability of the obtained PBHC random copolymers is higher than that of PBC and increases with increasing the HC unit content. The enzymatic degradation study revealed that the biodegradation rate of the PBHC copolymers mainly depends not only on the degree of crystallinity and melting temperature but also on the type of crystalline structure, while the composition and microstructure dependences of biodegradability are negligible. [ABSTRACT FROM AUTHOR]

Abstract: Poly(butylene fumarate) (PBF) bearing reactive double bonds on the polymer main chains has been designed and synthesized by coupling with hexamethylene diisocyanate (HDI) under very mild condition. The chemical structure, conformational structure, crystal structure and molecular weight of PBF were systematically characterized by ATR-FTIR, 1H NMR, 13C NMR, GPC and WARD. The thermal properties, mechanical properties and biodegradability of PBF were carefully studied by DSC, mechanical testing and enzymatic degradation. The results of 1H NMR and 13C NMR spectra indicate that no isomerization or Ordelt saturation reaction of trans Cace during the bulk polymerization and the reaction just proceeded in the way we designed. Linear PBF with high-molecular-weight has been successfully synthesized. This new type of uncrosslinked polyester is shown to have many merits such as relatively high melting point (T m), satisfactory processability and good mechanical properties. The impact strength of PBF is higher than 200 J/m; tensile and flexural strength can reach to 41.0 and 26.7 MPa, respectively. [Copyright &y& Elsevier]