Zwitterionic nano-objects having functionalizable hydrophobic core: Formation via polymerization-induced self-assembly and their morphology

Abstract

Functionalizable poly(pentafluorophenyl methacrylate) (PPFPMA) and zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) are two polymers with an extremely different solubility. It is, therefore, almost impossible to synthesize their block copolymers in a controlled manner using a conventional approach. Herein, it is demonstrated, for the first time, that the synthesis and in situ formation of nanoassemblies of their diblock copolymers (PMPC-b-PPFPMA) can be achieved via polymerization-induced self-assembly using reversible addition-fragmentation chain-transfer dispersion polymerization in ethanol as a selective solvent. The PMPC was synthesized as the first block and further employed as a macro chain transfer agent (PMPC Macro-CTA) for the synthesis of the PPFPMA second block. In situ self-assembled nanostructures of the diblock copolymers were found to be mostly spherical with a varied degree of inter-micellar aggregation depending on the solid concentration and the relative length of the two blocks. Apparently, the limited chain mobility of the core-forming PPFPMA block, due to π-π stacking and hydrophobic interactions, hampered the formation of nanostructures of high-order morphologies. It is possible to perform core functionalization via post-polymerization modification with 1-pyrenemethylamine to yield fluorescently labeled nanostructures that may be applicable as biocompatible and non-fouling nanocarriers and nanosensors in the future.