A Light and pH Dual-Stimuli-Responsive Block Copolymer Synthesized by Copper(0)-MediatedLiving Radical Polymerization: Solvatochromic, Isomerization, and“Schizophrenic” Behaviors.

A “schizophrenic” blockcopolymer (poly[1′-(2-methacryloxyethyl)-3′,3′-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2′-indoline)]-b-poly(acrylic acid) (PSPMA-b-PAA)) was synthesizedby sequential copper(0)-mediated living radical polymerization (Cu(0)-mediatedLRP) at 30 °C in an oxygen-tolerant system followed by hydrolysisof the resulting polymer. The solvatechromic behaviors of the PSPMA10-b-poly(t-butyl acrylate)40(PSPMA10-b-PtBA40) and PSPMA10-b-PAA40block copolymers in organic solvents were investigated byUV–vis spectroscopy. The PSPMA10-b-PtBA40stabilizes the nonpolar photoisomerand is not sensitive to the polarity of the solvent, while the PSPMA10-b-PAA40stabilizes the planarzwitterionic form without irradiation. Furthermore, light-inducedisomerization of spiropyran (Sp) moieties from Sp to merocyanine (Mc)was demonstrated. Finally, the “schizophrenic” micellizationbehavior of as-prepared copolymer in aqueous solution regulated bylight and pH stimuli was vividly demonstrated, and the reversibilityof micellization processes performed in this study was also examined.The large compound micelles can bring out a gradually extended andeven transformed conformation with increasing deprotonation degreeat pH > pKa. [ABSTRACT FROM AUTHOR]