Well-controlled spiropyran functionalized polystyrenes via a combination of anionic polymerization and hydrosilylation for photoinduced solvatochromism. (20th January 2021)

• Record Type: Journal Article
• Authors: Zhang, Ruixue; Han, Li; Ma, Hongwei; Lei, Lan; Li, Chao; Zhang, Songbo; Bai, Hongyuan; Li, Yang
• Is Part Of: Polymer. Volume 213(2021)
• Publication Date: 2021-01-20
• Subjects: Anionic polymerization -- SP in-Chain functionalized PSs -- Photoinduced solvatochromism; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2020.123311
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Si –H-functionalized polystyrene ( P S–SiH) with a well-controlled molecular weight and narrow polydispersity index (PDI) was synthesized via anionic polymerization (AP) of (4-vinylphenyl)-dimethyl-silane (VPDMS), i.e., PVPDMS ( M n = 2.5 kg/mol, PDI = 1.16). Spiropyran (SP) derivatives as the photo-responsive function, i.e., S P-phenyl-Yne (M1 ) and S P-biphenyl-Yne (M2 ) bearing the same alkyne (Yne) terminals and different spacers (phenyl/biphenyl), were used to modify the resulting PVPDMS via hydrosilylation, affording S P-functionalized PSs (PVPDMS-SPM1 /SPM2 ) with a defined number of SP attachments. The photoinduced solvatochromism of SP derivative small molecules and polymers was investigated in solvents of different polarities. The time-dependent conversion of different isomers was mainly qualitatively tracked by spectroscopic methods, allowing the transfer pathways among different SP isomers to be proposed. The appearance of trans -merocyanine (MC) H-aggregations was detected in the UV–Vis spectra of both SP derivative small monomers and polymers in relatively low-polarity solvents. Moreover, a discoloration process caused by the appearance of cis -MCs was observed under continuous illumination, which demonstrated that the appearance of aggregations and cis -MCs relied on the solvent polarity. More importantly, PVPDMS as the polymer backbone effectively decreased the rate of structural trans -to- cis MC conversion, indicating an inhibiting effect of the steric hindrance on the appearance of cis -MC molecules. Graphical abstract: Image 1 Highlights: Preparation of SP functionalized polystyrenes via anionic polymerization and hydrosilylation. The effect of solvent and molecular structures on photoinduced solvatochromism of SP derivative was investigated. The possible transfer pathways among different SP isomers was proposed.