Tunable topology and mechanically-induced order-parameter stiffening in density-modulated vesicles

Self-assembly is a fundamental phenomenon prevalent in nature, yielding a variety of geometric and structural patterns. In biological systems, liquid-crystalline components, such as actin, microtubules, and filaments, play crucial roles in shaping the cellular environment. In this study, we have mimicked these natural self-assembly processes through creating liquid-crystalline block copolymers that spontaneously assemble into density-modulated vesicles in solution. We have established a general state diagram that illustrates various vesicle shapes and topology, ranging from spherical to ellipsoidal and sharply elongated, based on the balance between liquid-crystalline ordering and the elastic deformability of the vesicles. These distinct features are characterized by complex, spatially-varying and density-modulated orientational fields and defects, leading to topology-coupled mechanical deformation when subjected to pressure. Our findings provide guidelines for leveraging liquid-crystalline interactions in designing synthetic anisotropic microstructures, and controlling their local mechanical properties.