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)-<i>alt</i>-poly(ethylene glycol)) containing photosensitive stiff-stilbene derivative, as the precursor. The photoinduced <i>trans</i>-to-<i>cis</i> 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 (<i>Đ</i>) 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.