RESUMEN
A novel silicone resin (SR-OH) containing phenolic hydroxyl (Ph-OH) groups was designed and synthesized via co-hydrolysis/condensation and catalytic hydrogenation. During the curing process, the cross-linking degree of the resin was further increased by the Si-O-Ph bonds formed by the reaction of the Ph-OH and terminal Si-OH groups. Thermogravimetric analysis (TGA) showed that the cured resin product exhibited excellent thermal and thermo-oxidative stability, which was much higher than that of a typical methyl phenyl silicone resin (SR-Ph). The temperature at which 5% weight loss occurs (T d5) was up to 606 °C (nitrogen) and 542 °C (air), and its char yield at 800 °C was 91.1% and 85.3% in nitrogen and air, respectively. The significant improvement in thermal stability was mainly attributed to the formation of Si-O-Ph bonds which not only increases the cross-linking degree of the resin but also significantly prevents degradation by the 'back-biting' and oxidative cleavage.
RESUMEN
Silicone resin is a high-temperature resistant material with excellent performance. The improvement of its thermal stability has always been the pursuit of researchers. In this paper, a sequence of silicone resins containing trifluorovinyl ether groups were prepared by the co-hydrolysis-polycondensation of methyl alkoxysilane monomers and {4-[trifluorovinyl(oxygen)]phenyl}methyldiethoxysilane. The structures of the silicone resins were characterized by FT-IR and 1H NMR. The curing process of them was studied by DSC and FT-IR spectra, and results showed that the curing of the resins included the condensation of the Si-OH groups and the [2 + 2] cyclodimerization reaction of the TFVE groups, which converted to perfluorocyclobutane structure after curing. The thermal stability and thermal degradation behavior of them was studied by TGA and FT-IR spectra. Compared with the pure methyl silicone resin, silicone resins containing TFVE groups showed better thermal stability under both N2 and air atmosphere. Their hydrophobic properties were characterized by contact angle test. Results showed that PFCB structure also improved the hydrophobicity of the silicone resin.
RESUMEN
PSiQAEp-GH polymers were synthesized by the reaction of gelatin hydrolysate (GH) and polysiloxane quaternary ammonium salts containing epoxy group (PSiQAEp) with different molecular weight from 3147 to 12996. The results of FTIR, 1H NMR and 13C NMR showed that the reaction occurred between primary amino group of arginine in GH and epoxy of PSiQAEp. The XRD and DSC studies showed that the degree of short-range order of PSiQAEp-GH reduced and its glass transition temperature (Tg) lowered more than 10 °C compared with GH. The determinations of moisture absorption and contact angle (CA) indicated that the hydrophobility of PSiQAEp-GH was better than GH. The tests of inhibitory zone and minimum bactericidal concentration (MBC) illustrated that the PSiQAEp-GHs exhibited excellent antibacterial activity, and the antibacterial activity depended on both the chemical structure of PSiQAEp-GHs and the biological structure of the bacteria.
