Photo-controlled gelation of pH-responsive ABA triblock copolymers via synergistic integration of photobase generator

The fast sol-gel transition of ABA triblock copolymers in aqueous solution has demonstrated excellent promise for various applications. However, the occurrence of gelation behaviors often needs precise temperature control or concentration regulation. Considering the advantages of precisely spatiotemporal control and noninvasive manner, the photo-controlled gelation behaviors are desirable but still remain a significant challenge, especially for ABA triblock copolymers. Herein, we reported a facile strategy for spatiotemporal photo-modulation of reversible gelation of ABA triblock copolymers. The pH-responsive ABA triblock copolymers [poly( N,N - diethylaminoethyl methacrylate)- b -polyethylene glycol- b -poly( N,N -diethylaminoethyl methacrylate), PDEAEMA-PEG-PDEAEMA] were synthesized and used for preparing photobase generator (Malachite green carbinol base, MGOH)-containing micellar solution. Under ultraviolet irradiation, the MGOH in PDEAEMA-PEG-PDEAEMA micelles could rapidly generate OH − , resulting in deprotonation and hydrophobization of PDEAEMA chain, finally achieving micellar reconstruction and in situ gelation transition. This study demonstrated not only a photo-controlled reversible sol-gel transition of ABA triblock copolymers without the limitations associated with conventional photosensitive reagents, but also a low-cost and fast system for intelligent monitoring, early warning, and rapid shielding of ultraviolet rays. Considering the easily available agents, simple preparation process and high flexibility in tuning hydrogel properties, this strategy opens up a promising avenue to develop photo-controlled hydrogels for various applications without involving complex synthesis of photosensitive polymers.