Preparation of polycaprolactone-based 2D platelets via living crystallization-driven self-assembly

Here we describe the preparation of two-dimensional (2D) polymer platelets based on poly(ε-caprolactone) (PCL) using living crystallization-driven self-assembly (CDSA), a seeded growth strategy that uses crystallization as a directional driving force to achieve epitaxial growth with controlled size and shape. The method integrates ring-opening polymerization for preparation of PCL segments, reversible addition-fragmentation chain-transfer polymerization for corona-forming blocks, sonication fragmentation or the flash-freezing method to generate seed particles and living CDSA to produce uniform and monodisperse 2D nanostructures. These 2D platelets are prepared from mixtures of PCL-based homopolymers and PCL-b-PDMA block copolymers, where PDMA refers to poly(N,N-dimethylacrylamide); similar solvophilic blocks with comparable properties could also be employed in place of PDMA. In this system, the semicrystalline PCL block provides the driving force for self-assembly, while the amorphous solvophilic corona block imparts colloidal stability and tunes interfacial properties. Owing to the living nature of CDSA, the platelet dimensions scale linearly with the unimer-to-seed ratio, enabling reproducible control over platelet area, layered structures and overall morphology. The Protocol is compatible with a broad range of PCL-based polymers bearing diverse functional groups and corona chemistries, and it can be readily adapted to incorporate responsive, supramolecular or fluorescent components. The resulting 2D platelets serve as versatile model systems for probing CDSA mechanisms and as platforms for optical and stimuli-responsive materials. The complete workflow-from polymer synthesis to structural characterization-can be completed within ~2 weeks and can be performed by researchers with basic experience in polymer synthesis and self-assembly.