Silicon (Si) anodes display high specific capacity but mostly suffer from poor cycling ability owing to their dramatic volume expansion during the discharge/charge process. An effort was devoted to developing new polymeric binders that could effectively mitigate the capacity fading of Si anodes. Herein, aqueous binders of chitosan-g-poly(acrylic acid) copolymer (CS−PAA) and its sodium salt (CS−PAANa) have been synthesized and applied as the functional binders for the stabilization of Si anodes in lithiumion batteries. The structure and properties of Si anodes based on CS−PAA and CS−PAANa were comparatively characterized by using poly(vinylidene fluoride), chitosan, and poly(acrylic acid) as reference binders. Unlike conventional 1D structural binders, the CS−PAA and CS−PAANa form a cross-linked (3D) network during curing, which maintains mechanical integrity to mitigate Si nanoparticle pulverization effectively. Moreover, the abundant polar groups including carboxylic acid (−COOH) and carboxylate (−COO − ) in the two binders could react with both Si nanoparticles and copper (Cu) current collector to offer robust adhesion, significantly improving electrode integrity after the repeated delithiation/lithiation cycles. Benefitting from the structural advantages, the Si/CS−PAA and Si/CS−PAANa electrodes deliver stable cycling performances of 1243 and 1608 mA h/g at 420 mA/g after 100 cycles.

SUMMARYPolyb-phenylene sulfide) (PPS) oligomers were synthesized from sodium sulfide (SS) and p-dichlorobenzene @-DCB) in hexamethylphosphoramide (HMPA) under atmospheric pressure. The effects of reaction time, temperature, and monomer ratio on end groups and molecular weight of PPS oligomers were investigated. The results show that the molecular weight is controlled by the above parameters. Thiol-terminated PPS oligomers were prepared by two routes. One was the polycondensation of p-DCB with equimolar SS followed by the reaction with an extra amount of SS. The other was the depolymerization of high molecular weight PPS with SS in HMPA. The results show that the second route is the best one for preparation of thiol-terminated PPS oligomers. Carboxylterminated PPS telechelic oligomers were produced through the reaction of thiol-terminated PPS oligomers with p-chlorobenzoic acid.

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Ultrahigh molecular weight polyethylene (UHMWPE) is an excellent material with high performance, but it is very difficult to covalently introduce functional groups on its surface owing to its inherently inert structure, which constrains its further application. In this study, vinyl triethoxysilane (VTEOS) containing hydrolysable alkoxyl groups was in situ grafted on UHMWPE by air plasma treatment. The plasma treatment conditions for VTEOS grafting were optimized. The structure of the modified UHMWPE was characterized with FTIR and XPS. The relatively high VTEOS content was obtained when the treating conditions were about 20 W, 125 Pa for 10 min. And FTIR results showed that the grafted structure on the surface was stable for long time duration in the ambient environment. After the treatment, the roughness of the surface increased and the water contact angle of the modified sample dropped to 47.5° from 92.8° of the unmodified one. TGA and XRD results indicated that plasma treatment would not change the bulk structure of UHMWPE greatly. Cell culture experiments showed that fibroblasts on the modified samples had notably high viability and proliferation rate with good adhesion shape. Hence, it might be an effective method to improve the surface properties of UHMWPE for biomedical applications by plasma-induced in-situ grafting with VTEOS. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 321-332, 2018.

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