聚丙烯酸-b-聚(N-异丙基丙烯酰胺)嵌段共聚物的合成及其温度和pH值敏感性自组装研究

Synthesis and Self-assembly of Temperature- and pH-Sensitive Diblock Copolymer of Poly(acrylic acid)-b-poly(N-isopropylacrylamide)

通过原子转移自由基聚合方法,在丁酮/异丙醇混合溶剂中合成了分子量可控和分布较窄的聚丙烯酸叔丁酯-b-聚N-异丙基丙烯酰胺(PtBA-b-PNIPAM)嵌段共聚物,用GPC和1H NMR对其结构进行了表征.PtBA-b-PNIPAM在甲苯中水解得到聚丙烯酸-b-聚N-异丙基丙烯酰胺(PAA-b-PNIPAM).用动态光散射技术对PAA-b-PNIPAM在水溶液中的自组装行为随pH值和温度变化的响应进行了初步研究.

Diblock copolymer of poly （ t-butyl acrylate） -b-poly （N-isopropylacrylamide） （ PtBA-b-PNIPAM ） with designed molecular weight and narrow molecular weight distributions was synthesized by sequential atom transfer radical polymerization （ATRP） of butyl acrylate and N-isopropylacrylamide using CuCl/（ 1,1,4,7,7- pentamethyl diethylenetriamine （ PMEDTA ） and CuCl/tris （ 2-dimethylaminoethyl ） amine （ Me6 TREN ） as the catalyst respectively in a mixture solvent of butanone and 2-propanol. Temperature- and pH-sensitive block copolymer of poly （ acrylic acid） -b-poly （ N-isopropylacrylamide ） （ PAA-b-PNIPAM ） was realized after hydrolysis of PtBA-b-PNIPAM in toluene. PAA-b-PNIPAM existed as single molecules in aqueous solution at 25℃ and pH 〉 pKa of PAA. Increasing temperature above LCST of PNIPAM or decreasing pH value lower pKa of PAA respectively formed PNIPAM-core micelles or PAA-core micelles.