Temperature/pH-sensitive hydrogels prepared from pluronic copolymers end-capped with carboxylic acid groups via an oligolactide spacer

The Pluronic F127 triblock copolymer was end-capped by carboxyl groups using a degradable oligolactide as a spacer to confer pH- and thermo-sensitive properties. With increasing chain length of the oligolactide, the temperature-dependent sol-gel transition curve was significantly shifted to higher concentration with concomitant narrowing or the gelation temperature range. Carboxylic acid end-capped Pluronic also exhibited a peculiar pH-dependent sol-gel transition behavior. At 37 degrees C, sharp gel-to-sol and sol-to-gel transitions were observed around pH = 4.8 and 8.2, respectively. The pH-dependent of phase transition was caused by introduction carboxylic acid groups at the ends of Pluronic F127. [GRAPHICS] PMMA. [GRAPHICS] in situ reduction, a large number of metal-based functional materials can be prepared. PVP is alkaline, and thus capable of catalyzing the sol-gel process to generate an inorganic shell. Furthermore, pre-formed nanoparticles can also be absorbed by the shell through specific interactions. The PS core is not infiltrative during synthesis, and hollow rings can be derived after the polymer templates are removed. [GRAPHICS] b