Unimodal and Well-Defined Nanomicelles Assembled by Topology-Controlled Bicyclic Block Copolymers

This study provides first insights into the micellization behavior and micellar morphologies of bicyclic amphiphiles in four different topologies: bicy-BCP-A, bicy-BCP-B, bicy-BCP-C, and bicy-BCP-D, consisting of poly(n-decyl glycidyl ether) and poly(2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether) blocks in equivalent molar fractions. Quantitative synchrotron X-ray scattering analysis reveals that all bicyclic amphiphiles self-assemble into unimodal nanomicelles consisting of core, dense corona, and soft corona structural components. The micelles also demonstrate substantial size reductions (56.7-70.7%) compared to micelles of their linear counterpart (l-BCP). The critical micelle concentration, stability, and structural parameters (shape, size, and others) of nanomicelles are differentiated by controlling the bicyclic topology types. bicy-BCP-A, -B, and -C form oblate ellipsoidal micelles, whereas bicy-BCP-D and l-BCP assemble into prolate ellipsoidal micelles. The size is found to be in the following order: bicy-BCP-D < bicy-BCP-C < bicy-BCP-B < bicy-BCP-A l-BCP. Furthermore, the structural stability is in the following order: l-BCP < bicy-BCP-D bicy-BCP-B < bicy-BCP-C < bicy-BCP-A. These results indicate that the topology-controlled bicyclic block copolymers can be used as a desirable platform for developing high-performance functional core-shell nanoparticles for advanced applications in various fields, including smart drug delivery, biomedical imaging, cosmetics, advanced coating appliances, and molecular electronics.