From Janus Spheres to Twisted Patchy Platelets and Their 3D Assemblies by Co-Crystallization-Driven Self-Assembly

Surface-compartmentalized particles, such as Janus and patchy micelles, have attracted growing interest owing to their unique corona properties, enabling diverse applications. Crystallization-driven self-assembly is a powerful tool for preparing worm-like patchy micelles with crystalline cores. However, platelet-like (2D) micelles and 3D assemblies with a nonconcentric arrangement of corona patches have not yet been realized. Here, we report on the self-assembly of polystyrene-block-poly(l-lactide)-block-poly(tert-butyl methacrylate) (SLT) triblock terpolymers featuring a crystallizable PLLA middle block and two highly incompatible corona-forming blocks (PS and PtBMA). Direct dissolution of neat SLT at 45 °C in cyclohexane, a selective solvent for the corona-forming blocks, yields spherical Janus micelles with an amorphous PLLA core, as crystallization is strongly hindered under these conditions. Surprisingly, upon blending SLT with the PLLA homopolymer, cocrystallization-driven self-assembly results in twisted platelet-like micelles with a nonconcentric, nanometer-sized patchy corona that further form defined 3D assemblies. The high interfacial activity of the twisted patchy platelets allows their use in emulsion stabilization, underlining their application potential. Notably, the twisted patchy platelets exhibit a higher interfacial activity with respect to the corresponding spherical patchy micelles, which is in contrast to the behavior of Janus discs and spheres.