A novel fast responsive thermo-sensitive poly(N-isopropylacrylamide)-clay nanocomposites hydrogels modified by nanosized octavinyl polyhedral oligomeric silsesquioxane.

The preparation of a novel fast response thremosensitive hydrogel was investigated by incorporating nanosized octavinyl polyhedral oligomeric silsesquioxane (OvPOSS) particles into inorganic clay-crosslinked poly(N-isopropylacrylamide) (PNIPA) nanocomposites hydrogels (NC gels). The resulting hydrogels named as P-NC gels involving both the strategies of NC gels and double network gels (DN gels) were successfully synthesized via a two-step technique. The second PNIPA network crosslinked by OvPOSS were polymerized in the presence of the first clay-PNIPA network. The P-NC gels were characterized by FTIR, X-ray, DSC, UV/vis,spectra, SEM, mechanical properties and swelling behaviors measurements. The key factor for preparing homogenous P-NC gels with good transparency was the low concentration of OvPOSS (c(OvPOSS)) dispersed uniformly in polymer as a cross-linker. On the contrary, the high c(OvPOSS) led to the significant aggregation of the OvPOSS particles and thus resulted in the heterogeneity of gels. The SEM images of freeze-dried P-NC gels exhibited a highly interconnected microporous network structure, which could be adjusted by varying the amount of OvPOSS. The special porous morphology brought about an attractive faster swelling/deswelling rate than that of normal NC gels. All properties of P-NC gels displayed an obvious dependence on the concentration of incorporated OvPOSS. The excellent mechanical properties, tunable LCST, especially the fast deswelling rate make these hydrogels potential candidates for applications in drug release and other biological fields.

Macroscopic, free-standing Ag-reduced, graphene oxide Janus films prepared by evaporation-induced self-assembly.

A facile, efficient, and unique self-assembly process for the preparation of the macroscopic, free-standing, Ag-reduced, graphene oxide (Ag-RGO) Janus films, which exhibit a unique asymmetry of their two surfaces with macroscopic dimensions, is presented. A novel strategy using an evaporation-induced, self-assembly (EISA) process is shown to be a powerful and flexible method for synthesizing well-defined Janus thin films.

Solid-phase extraction of ursolic acid from herb using beta-cyclodextrin-based molecularly imprinted microspheres.

A new method was employed to solid-phase extract ursolic acid from Ilex kudingcha C. J. Tseng using molecularly imprinted microspheres (MIMs) as the sorbent. Using a surface molecular imprinting technique, MIMs for ursolic acid were prepared with bonded beta-CD and acrylamide in combination based on functionalized poly(glycidyl methacrylate) microspheres (F-PGMA). Compared with non-MIMs (NIMs), MIMs showed high adsorption capacity, significant selectivity, and good site accessibility for ursolic acid. The maximum static adsorption capacities of the MIMs and NIMs for ursolic acid were 42.5 and 4.9 micromol/g, respectively. Chromatographic analysis shows that ursolic acid and oleanolic acid could be separated well when MIMs were used as the stationary phase of HPLC. The conditions of molecularly imprinted SPE (MISPE) of ursolic acid from the herb extract were optimized using different concentrations of ethanol solutions as loading, washing, and eluting solutions. The successful extraction of ursolic acid by MIMs provided a possible innovative approach to separate ursolic acid from herb.