八乙烯基多面体低聚倍半硅氧烷-N-异丙基丙烯酰胺共聚物有机-无机杂化水凝胶的合成与表征

以N-异丙基丙烯酰胺(NIPAM)和八乙烯基笼形低聚倍半硅氧烷(OVPOSS)为单体,通过溶液自由基共聚合成了一系列P(OVPOSS-co-NIPAM)有机-无机杂化水凝胶.采用傅立叶红外光谱(FTIR)、扫描电镜(SEM)、X-射线衍射(XRD)、示差扫描量热仪(DSC)、热重分析仪(TGA)和动态粘弹谱仪(DMA)对其结构与性能进行了研究.结果表明可以通过控制投料比来调节P(OVPOSS-co-NIPAM)杂化水凝胶中POSS的实际含量;P(OVPOSS-co-NIPAM)杂化水凝胶的微观形貌为孔洞结构,随POSS含量的增加,孔径逐渐减小;所合成的P(OVPOSS-co-NIPAM)杂化水凝胶均具有温敏性,随着POSS含量的增加,其最低临界溶解温度(LCST)由33.0℃降低至30.0℃,均低于常规水凝胶(33.7℃);POSS的引入使PNIPAM水凝胶的玻璃化转变温度(Tg)由142℃升至148℃,并改善了其热稳定性和力学强度.

SYNTHESIS AND CHARACTERIZATION OF ORGANIC-INORGANIC HYBRID HYDROGELS BASED ON OCTAVINYL POLYHEDRAL OLIGOMERIC SILSESQUIOXANE AND N-ISOPROPYLACRYLAMIDE COPOLYMER

A novel series of organic-inorganic hybrid hydrogels based on (N-isopropylacrylamide) (NIPAM) and octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) (P(OVPOSS-co-NIPAM)) were synthesized by solution free radical polymerization.The products were characterized by FTIR,SEM,XRD,DSC,TGA and DMA methods.The results showed that OVPOSS could be introduced into PNIPAM matrix successfully by free radical polymerization.The actual POSS content in the hybrid hydrogel could be controlled by changing the feed ratio and increased from 2.3 wt% to 12.0 wt% with increasing the feed ratio from 5.0 wt% to 16.0 wt% .Typical hole structures of hydrogels were also observed in P(OVPOSS-co-NIPAM) hybrid hydrogels and the size of the holes decreased with increasing POSS content.Aggregation phenomenon of OVPOSS was observed in 12-P(OVPOSS-co-NIPAM) and 16-P(OVPOSS-co-NIPAM) hybrid hydrogels.All the synthesized hybrid hydrogels showed thermosensitive property.The lower critical solution temperatures (LCST ) of P(OVPOSS-co-NIPAM) hybrid hydrogels were lower than those of the conventional PNIPAM hydrogel and decreased gradually from 33.0℃ to 30.0℃ with the increase of POSS content.The introduction of the OVPOSS increased the glass transition temperature (Tg) of PNIPAM from 142.0℃ to 148.0℃ .The thermal stability of PNIPAM was improved and the thermal decomposition temperatures (Tdec) of PNIPAM increased from 385.0℃ to 391.3℃ ,which are higher than that of the conventional hydrogel.The mechanical property of PNIPAM was also improved and the strain of P(OVPOSS-co-NIPAM) hybrid hydrogels under the same stress decreased with increasing POSS content.