葡萄糖敏感微凝胶的溶胀动力学研究

SWELLING KINETICS OF P (NIPAM-co-AAPBA) MICROGEL IN GLUCOSE SOLUTION

通过沉淀聚合法合成了P(NIPAM-co-AA)微凝胶,然后在EDC催化下用3-氨基苯硼酸对微凝胶进行改性,制备了P(NIPAM-co-AAPBA)微凝胶.红外光谱检测证明改性完全.改性后的微凝胶仍具有很好的温敏性,但由于引入疏水的苯硼酸基团,微凝胶的体积相转变温度大大降低.P(NIPAM-co-AAPBA)微凝胶具有很好的葡萄糖敏感性,其粒径随葡萄糖浓度提高而增大,与此同时,体系的浊度随葡萄糖浓度提高而减小.因此可利用浊度法研究由葡萄糖引起的P(NIPAM-co-AAPBA)的溶胀动力学.结果表明,P(NIPAM-co-AAPBA)微凝胶溶胀平衡所需时间在百秒数量级,且葡萄糖浓度越高,体系达到溶胀平衡就越快.这一结果证明,P(NIPAM-co-AAPBA)微凝胶确比相同化学结构的宏观凝胶具有更快的响应速度.

Poly（N-isopropylacrylamide-co-acrylic acid）（P（NIPAM-co-AA）） microgel was synthesized by precipitation polymerization.Poly（N-isopropylacrylamide-co-3-acrylamidophenylboronic acid）（P（NIPAM-co-AAPBA）） microgel was obtained by the modification of P（NIPAM-co-AA） microgel with 3-aminophenylbornic acid under 1-ethyl-3-（3-dimethylaminopropyl）carbodiimide（EDC） catalysis.Almost complete conversion of the carboxylic groups in P（NIPAM-co-AA） microgel was confirmed by the disappearance of the peak at 1711 cm-1 in FTIR spectra.Both microgels are thermosensitive,however,the volume phase transition temperature of P（NIPAM-co-AAPBA） microgel is much lower than that of P（NIPAM-co-AA） microgel,as a result of the introduction of hydrophobic phenylboronic acid groups.The P（NIPAM-co-AAPBA） microgel exhibits good glucose-sensitivity,as its size increases with increasing glucose concentration.The increasing glucose concentration also results in a decrease in the turbidity of the microgel dispersion,which makes it possible to trace the kinetics of the glucose-induced swelling by turbidity.The kinetic curves were fitted with single-exponential function and the corresponding characteristic swelling times were obtained.The time required for the system to reach swelling equilibrium is on the magnitude of 102 s.The swelling rate increases with increasing glucose concentration.Compared with the macroscopic hydrogel with same composition,the glucose-induced swelling of P（NIPAM-co-AAPBA） microgel is much faster.However,compared with the swelling of PNIPAM microgels induced by temperature,the glucose-induced swelling is much slower.