Combining the power of heat and light: temperature-programmed photoinitiated RAFT dispersion polymerization to tune polymerization-induced self-assembly

Polymerization-induced self-assembly (PISA) of diblock copolymers has emerged as a promising method for large-scale preparation of polymer nano-objects with a diverse set of morphologies. Herein, we report a novel temperature-programmed photo-PISA method which combines the power of heat and light for precise control over the self-assembly process. Careful characterization of the samples prepared at predetermined temperatures by transmission electron microscopy (TEM) reveals an intermediate structure (large compound vesicles (LCVs)) which provides important mechanistic insights into the morphological variation during a vesicle-to-microsphere transition. Tunable morphologies can be precisely prepared by performing polymerizations with different programmed temperature profiles. Moreover, this method enables the large-scale preparation of LCVs with uniform size in water. This temperature-programmed photo-PISA approach not only leads to unprecedented access to the elucidation of the PISA mechanism, but also provides a versatile platform for large-scale preparation of interesting structures.