Structure And Properties Of Polymer Nano-Composites Involving Polyhedral Oligomeric Silsesquioxanes (POSS)

Octa (propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) was used as a nanocrosslinking agent to prepared the crosslinked poly(N-isopropylacrylamide) (PNIPAM) networks with POSS content up to 50 wt%. The inter-component crosslinking was achieved via the reaction between N-H moieties in amide group of PNIPAM and epoxide groups of OpePOSS. The crosslinked structures were investigated by means of Fourier transform infrared spectroscopy (FTIR). The atomic force microscopy (AFM) showed that the POSS-containing crosslinked PNIPAM nanocomposites were formed. Differential scanning calorimetry (DSC) shows that the PNIPAM nanocrosslinked by POSS displayed the enhanced glass transition temperatures (Tg's). The nanocomposites was displayed the improved thermal stability compared to control PNIPAM in terms of thermogravimetric analysis (TGA). The POSS-crosslinked PNIPAM exhibited the characteristics of hydrogels, just like the PNIPAM crosslinked by N,N'-methylenebisacrylamide (viz. the conventional crosslinker) via free radical copolymerization. With the moderate contents of POSS, the POSS-containing hybrid hydrogels displayed much faster response rates in swelling, deswelling and re-swelling experiments than control PNIPAM hydrogel. The improved hydrogel properties have been interpreted on the basis of the formation of the nanosized hydrophobic microdomains around the POSS moieties (i.e., the nanocrosslinking sites).A novel organic-inorganic interpenetrating polymer network (IPN) was prepared via in situ crosslinking between octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) and 2,2-bis(4-hydroxyphenyl)propane in the presence of...