Abstract:A series of temperature-responsive core cross-linked star polymers (P(PEGA-co-DEGA) CCSP), in which poly(methoxypolyethylene glycol-co-di(ethylene glycol) ethyl ether acrylate) (P(PEGA-co-DEGA)) served as the temperature-responsive arm, have been successively prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization using the “arm-first” approach. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H-NMR) have been applied to characterize the structure and composition of the resultant polymers. The molecular weight of the P(PEGA-co-DEGA) arm and the corresponding P(PEGA-co-DEGA) CCSP was obtained by gel permeation chromatography (GPC), which showed that the efflux time of P(PEGA-co-DEGA) CCSP was significantly shortened compared with its corresponding arm, indicating the successful preparation of CCS polymer. The phase transition behavior of the resultant CCSP was evaluated through UV-vis spectroscopy. The results showed the low critical solution temperature (LCST) of P(PEGA-co-DEGA) CCSP showed a downward trend with the increasing DEGA content in the P(PEGA-co-DEGA) arm. The LCST of P(PEGA-co-DEGA) CCSP was also affected by the pH value of the solution due to the ionization of the carboxylic acid groups at the end of the polymer chains, which showed an upward trend with the increases of solution pH value. The experimental results indicated that the LCST of P(PEGA-co-DEGA) CCS could be controlled at a range of 49~82 ℃ by adjusting the moles ratios of PEGA and DEGA in the arm and the pH of solution. Furthermore, the prepared CCS polymer demonstrates a narrower temperature range of phase transition and thus faster phase separation process in comparison to the corresponding linear arm.