The amphiphilic random copolymer precursor P(SPMA-co- tBMA) is synthesized by atom transfer radical polymerization.
The acrylated photo-responsive monomer (SPMA) is first prepared (see Scheme 2) and its chemical structure is confirmed by 1H NMR (see Fig. S1).
The appearance of new peaks at 5.83, 6.06 and 6.38 ppm which belong to the protons of carbonecarbon double bond verifies the successful synthesis of the light-responsive monomer.
Afterward, the monomer containing spiropyran is copolymerized with tBMA by ATRP.
The peaks of each monomer are observed in the 1H NMR spectrum of the resulting product, indicating that P(SPMA-co-tBMA), the intermediate copolymer, has been successfully synthesized (see Fig. S2).
The actual composition of the copolymer is estimated by the peak integrals attributed to methyl protons of tBMA (1.39 ppm, 1.47 ppm) and the protons of benzopyran (7.98 ppm).
The actual molar ratio of repetitive unit in the resulting copolymer is 1: 20.4 (SPMA: tBMA) which is exactly close to the feed ratio (1: 20), suggesting the “control/living” character of ATRP. The molecular weight (Mn) and polydispersities index (PDI) are determined by GPC (see Fig. S3).
The Mn of precursor copolymer P(SPMA-co-tBMA) is 38400, and the PDI is 1.48.