Synthesis of Temperature and Light Sensitive Copolymers with Controlled Aggregation during Phase Transitions

Abstract

Two thermosensitive copolymers of acrylates (PMP/PEP) and a thermo/light sensitive copolymer of acrylate with acrylamide (PMABz) are synthesized via a ring‐opening reaction and subsequent radical polymerization using a facile one‐pot method. The lower critical solution temperature (LCST) of PMP and PEP shows a dependence on the content of the structural unit and can be easily tuned to 18–35 °C by mercaptoethanol‐mediated control of the molecular weight. The isomerization of PMABz can be reversibly induced by alternating irradiation at 365 nm to produce the cis form and at 254 nm to produce the trans form. The LCST of cis‐PMABz (40.3 °C) is significantly higher than that of trans‐PMABz (37.8 °C) because of its higher hydrophilicity. Furthermore, the particle size of aggregated PMABz can be controlled from 665 nm (for the cis form) to 996 nm (for the trans form) during the heating run. After quenching the PMABz solution, PMABz particles have repeating patterns, such as leaf veins or hollow containers, indicating their potential applicability.

Boosting the photo-switchability of double-responsive water-soluble polymers by incorporating arylazopyrazole dyes

“…Second, the shifts of T trans achieved have been mostly limited to a few degrees. 13,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] For many of the envisaged uses, this is too small. As an exception, Menzel and coworkers 32 succeeded to shift T trans of azobenzene-bearing polyacrylamides upon irradiation by up to 14 1C.…”