Co-assembly confined polymerisation of polydiacetylene acids with intrinsically narrow dispersity

Polydiacetylene (PDA) materials are typically obtained through solid-state topochemical polymerisation of diacetylene monomers, a process that strongly depends on precise molecular packing and often leads to limited control over molecular weight and dispersity. Herein, we report a co-assembly-confined polymerisation strategy for the synthesis of polydiacetylene acids with intrinsically narrow dispersity. Phenyl diacetylene acid and 1-naphthalenemethylamine form co-assembled precipitates via acid – base interactions and aromatic stacking, providing a spatially restricted environment that satisfies the geometric requirements for topochemical polymerisation. Upon UV irradiation, efficient polymerisation of diacetylene units occurs within the precipitated phase. Subsequent side-chain amidation renders the polymers soluble, enabling solution-state molecular weight characterisation. Gel permeation chromatography reveals consistently narrow dispersity (Đ =1.1 ~ 1.2) across different polymerisation temperatures, while the apparent molecular weight remains tunable. This work demonstrates a simple and reproducible materials-oriented strategy to suppress chain-length divergence in polydiacetylene systems, offering new opportunities for controlled PDA materials.