Non-spherical morphologies from cross-linked biomimetic diblock copolymers using RAFT aqueous dispersion polymerization

The RAFT synthesis of cross-linked diblock copolymer nanoparticles was explored using an aqueous dispersion polymerisation formulation. This diblock copolymer comprised biomimetic poly(2-methacryloyloxy)ethyl phosphorylcholine) (PMPC) stabilizing chains and a highly cross-linked poly (2-hydroxypropyl methacrylate) (PHPMA) core-forming block. At either zero or relatively low levels of ethylene glycol dimethacrylate (EGDMA) cross-linker, only spherical morphologies were observed. However, using higher levels of EGDMA led to increasing particle anisotropy, with both a worm-like morphology and a novel 'lumpy rod' morphology (comprising fused nano-sized aggregates of primary spherical particles) being observed.