A Light and pH Dual-Stimuli-Responsive Block Copolymer Synthesized by Copper(0)-Mediated Living Radical Polymerization: Solvatochromic, Isomerization, and "Schizophrenic" Behaviors

作者：Zhou, Yin Ning; Zhang, Qing; Luo, Zheng Hong^*

来源：Langmuir, 2014, 30(6): 1489-1499.

DOI：10.1021/la402948s

• Living radical polymerization
• Micellization behavior
• Micellization process
• Poly(acrylic acid )
• Stimuli-responsive
• Transformed conformation
• UV-vis spectroscopy
• Zwitterionic forms

A "schizophrenic" block copolymer (poly[1'-(2-methacryloxyethyl)-3',3'-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2'-indoline)]-b-poly(acrylic acid) (PSPMA-b-PAA)) was synthesized by sequential copper(0)-mediated living radical polymerization (Cu(0)-mediated LRP) at 30 degrees C in an oxygen-tolerant system followed by hydrolysis of the resulting polymer. The solvatechromic behaviors of the PSPMA(10)-b-poly(t-butyl acrylate)(40) (PSPMA(10)-b-PtBA(40)) and PSPMA(10)-b-PAA(40) block copolymers in organic solvents were investigated by UV-vis spectroscopy. The PSPMA(10)-b-PtBA(40) stabilizes the nonpolar photoisomer and is not sensitive to the polarity of the solvent, while the PSPMA(10)-b-PAA(40), stabilizes the planar zwitterionic form without irradiation. Furthermore, light-induced isomerization of spiropyran (Sp) moieties from Sp to merocyanine (Mc) was demonstrated. Finally, the "schizophrenic" micellization behavior of as-prepared copolymer in aqueous solution regulated by light and pH stimuli was vividly demonstrated, and the reversibility of micellization processes performed in this study was also examined. The large compound micelles can bring out a gradually extended and even transformed conformation with increasing deprotonation degree at pH > pK(a).

• 出版日期2014-2-18
• 单位上海交通大学