Phase-separation and photoresponse in binary azobenzene-containing polymer vesicles

Understanding the photoresponse of azobenzene polymer in different conditions is essential for the potential application of azobenzene-based technologies. Herein, the microscale, photoresponsive hybrid polymersomes (polymer vesicles) composed of binary blends of azobenzene-containing block copolymers is prepared. The Janus morphology which presents phase-separation within the surface of hybrid polymersomes is observed. The composition and photoisomerization characteristic time of different domains are studied with Laser Trapping Raman Spectroscope (LTRS) system. The results indicated that the morphology of polymersomes can be tuned by the ratio of azobenzene-containing copolymer contents. We find the photoisomerization rate of azobenzene in hybrid vesicles is marginally slower than those in pure vesicles. These experiments provide a quantitative measurement method for dynamic photoresponse of azobenzene hybrid polymersomes.