Preparation And Properties Of POSS-hybrided Hydogel Composites

In this study, on the basis of the synthesis of octavinyl-polyhedral oligomeric silsesquioxanes(Octavinyl-POSS), using Octavinyl-POSS as reactive nanomaterial, POSS-hybrided PNIPAm/PAAc thermo- and p H-sensitive hydrogels, POSS-hybrided micelles modified with MPEG and POSS-hybrided supramolecular hydrogels were designed and fabricated.First, a series of thermo- and p H-responsive POSS-hybrided hydrogels were prepared through the copolymerization of N-isopropylacrylamide(NIPAm) and acrylic acid(AAc) monomers using Octavinyl-POSS as the crosslinker via UV-initiated free radical polymerization. Swelling properties of the resultant hydrogels were studied by investigating p H- and temperature dependence of equilibrium swelling ratio and oscillatory swelling-deswelling kinetics. It was found that POSS-hybrided PNIPAm/PAAc hydrogels showed a reversible stimuli-responsiveness to both temperature and p H changes. Rheological studies indicated that the swollen hybrid hydrogels have good mechanical properties. In vitro release kinetics studies of methyl violet(MV) adsorbed in the hydrogels showed that the release profile of MV was in a sustained manner.Second, POSS-COOH was obtained via photo-induced thiol-ene “click” reaction between Octavinyl-POSS and large excess of mercaptopropionic acid(MPA). Methoxy polyethylene glycol(MPEG) modified POSS(POSS-MPEG) was subsequently prepared by coupling reaction between POSS-COOH and methoxy polyethylene glycol(MPEG) with a molecular weight of 1 000. The as-obtained POSS-MPEG was ready to form stable hybrid micelles when dispersed in aqueous solutions. Fluorescence measurement and laser particle analyzer were applied to confirm the critical micelle concentration(CMC) and particle size of POSS-MPEG micelle solutions. It was found that CMC and particle size could be modulated by varying the MPEG graft number of POSS-MPEG. In vitro release kinetics studies of Ibuprofen entrapped in the hybrid micelles showed that the release profile of Ibuprofen from hybrid micells displayed a sustained release behavior.Finally, POSS-hybrided supramolecular hydrogels were fabricated via the inclusion complexation between POSS-MPEG using as guest molecules and α-cyclodextrin(α-CD) in aqueous solutions. XRD and TGA measurements confirmed the formation of crystalline inclusion complexes in the obtained hybrid hydrogels, which improved the thermal stability of POSS-MPEG. Rheological measurements showed that the hybrid hydrogels displayed a rapid gelation time and shear-thinning behavior. The storage modulus(G’) and the viscosity of the resultant hydrogels could be modulated by varying the concentration and the graft number of the POSS-MPEG as well as the molar feed ratio of MPEG moieties to α-CD. The as-obtained supramolecular hydrogels displayed a Gel-to-Sol transition between 50 and 55℃. The in vitro release kinetics studies of pirarubicin hydrochloride entrapped in the supramolecular hydrogel showed that the release of pirarubicin hydrochloride from the POSS-hybrided hydrogels exhibited a sustained release profile.