Zwitterionic phosphorylcholine-based polymers have emerged as an intriguing materials platform due to enhanced stability and compatibility in biological settings. Poly(2-(methacryloyloxy) ethyl phosphorylcholine) (PMPC), containing anionic phosphate and quaternary amine moieties in a single repeat unit, serves as a model example in various design strategies of nanocarriers and bioconjugates. Engineering PMPC into oppositely-charged AB diblock polyelectrolytes results in associative phase separation to form zwitterionic polyelectrolyte complex (Z-PEC) micelles. However, subtle differences between the complexation behavior of Z-PECs and systems bearing uncharged, neutral blocks (e.g. polyethylene oxide) remain unclear, complicating the interplay of overarching physical and ionic contributions to PEC formation and behavior. To alleviate this uncertainty, we rapidly synthesized a series of well-defined, PMPC-based diblock copolymers via aqueous reversible addition chain-transfer (RAFT) polymerization using a parallel synthesizer. This method of accelerated synthesis allowed us to directly compare libraries of PMPC systems with an assortment of charged building blocks. Product purity, composition, and molecular weight were characterized through proton nuclear magnetic resonance spectroscopy and size exclusion chromatography. Resulting polymers were studied to determine the effects of molecular weight, constituent monomer, and ionic strength on (1) the self-assembly of micelles in water and (2) the size and stability of complex-core micelles over time with multi-angle light scattering. Ongoing study of these parameters on the quality of Z-PEC hybrids will enable more precise and tailorable complex materials for relevant biotechnologies such as the encapsulation and delivery of nucleic acids, peptides, proteins, and other biomolecules.

Synthesis and assembly of zwitterionic PMPC-based block copolymers

2019 Spring National Meeting

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