Morphology Rearrangement by Mixing of Internally Hydrogen-Bonded Nanoparticles Comprising Triazine-Based Amphiphilic Diblock Copolymers

The self-assembly of block copolymers holds significant potential for designing functional nanoparticles in materials science, nanomedicine, and nanotechnology. While the self-assembly of amphiphilic diblock copolymers is relatively well understood, the influence of specific supramolecular interactions, particularly hydrogen bonding, in directing their morphological behavior remains largely unexplored. In this study, it was demonstrated that nanoparticles self-assembled in water/DMSO (75/25 vol/vol; 2 mg/mL) comprising amphiphilic diblock copolymers with a small amount of triazine-based guanine-cytosine (GCB) motifs incorporated in the hydrophobic block can undergo spontaneous rearrangement into new morphologies on mixing. For example, mixing spheres with vesicles resulted in spontaneous transformation into worms (nanofibers), and this transformation was accelerated at elevated temperature. The hydrogen bonding motif features three complementary hydrogen bonding sites on either side of the nucleobase unit, thereby having a Janus character. Amphiphilic diblock copolymers comprising dimethyl acrylamide (hydrophilic segment) and n-butyl acrylate (hydrophobic segment) were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization with a variable content of acrylate monomer functionalized with the Boc-protected form of the GCB motif as part of the hydrophobic segment. The present work represents a completely new approach for controlling self-assembly processes, paving the way for the design of functional nanoparticles for a range of applications.