Area-Controllable Nanoplatelets from Rapid Photocontrolled Living Crystallization-Driven Self-Assembly of an Alternating Copolymer

Photocontrolled living self-assembly has attracted considerable interest due to its noninvasive, remote control, and real-time features; however, it has remained much less explored compared to other stimuli-responsive self-assembly systems. Here, a novel photocontrolled living crystallization-driven self-assembly (P-CDSA) system was constructed by employing an alternating copolymer, poly((hexylthienyl stiff-stilbene)-alt-poly(ethylene glycol)) containing photosensitive stiff-stilbene derivative, as the precursor. The photoinduced trans-to-cis isomerization of the stiff-stilbene derivative segments could occur quickly upon 365 nm light irradiation, leading to a rapid P-CDSA process producing size-controllable nanoplatelets within 2 min at room temperature. Taking advantage of the repetitive characteristic of alternating copolymers, the nanoplatelet morphology was independent of the molecular weight (MW) and its distribution (Đ) of the copolymer. The areas of the nanoplatelets were precisely controlled by adjusting the unimer-to-seed mass ratio, following a linear relationship. Additionally, the lengths of the major and minor axes followed a sublinear growth trend, enabling tailored nanoplatelet dimensions. The area could also be programmed by sequential light on/off switching, showing a linear dependence on light irradiation time. This study demonstrates the first example of photocontrolled two-dimensional CDSA and opens a new avenue for controlling over the area of 2D architectures.