Control over Aspect Ratio and Polymer Spatial Distribution\nof 2D Platelets via Living Crystallization-Driven Self-Assembly

The aspect ratios\nof nano- and micrometer-sized features in nature\nhave evolved to enable specific characteristics that are finely tuned\nfor optimizing strength, surface area, optics, and heat dissipation.\nDespite the importance of aspect ratios, precise control over the\naspect ratios of anisotropic polymeric nanoparticles is challenging\nto achieve and the formation mechanisms by which they occur are not\nfully understood. In this study, using the crystallization-driven\nself-assembly (CDSA) process, we achieved two-dimensional (2D) platelets\nwith precisely controlled aspect ratios through the rational compositional\nadjustment of various polycaprolactone (PCL)-based homopolymers (HP)\nand block copolymers (BCP). These polymer compositions exhibit distinct\npolymer crystallization rates, which allow for highly controlled aspect\nratios and polymer spatial distribution in 2D platelets. Brownian\ndynamics (BD) simulations provided an in-depth understanding of the\nformation of 2D platelets. The BD simulations help us further confirm\nthe nature of living epitaxial growth, simulate the structural order\nof polymer chains during the CDSA process, and demonstrate the influence\nof PCL length on the aspect ratio. Our work opens up new possibilities\nfor a nuanced understanding of the interplay between polymer composition,\ncrystallization rate, and morphology, providing a method for the controlled\nsynthesis of 2D nanostructures.