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.