Synthesis of Zwitterionic, Hydrophobic, and Amphiphilic Polymers: Via RAFT Polymerization Induced Self-Assembly (PISA) in Acetic Acid


Polymerization induced self-assembly (PISA) in acetic acid was employed to polymerize the hydrophilic sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate (DMAPS) and the hydrophobic monomer lauryl methacrylate (LMA). Polymerizations were conducted from a macro chain transfer agent (macro-CTA) consisting of 66% 2-hydroxyethyl methacrylate (HEMA) and 33% poly(ethylene glycol) methyl ether methacrylate FW ~ 300 Da (O300). A degree of polymerization (DP) of 50 was targeted for the macro-CTA in order to yield diblock copolymers with significantly larger 2nd blocks. From the poly(HEMA-co-O300) macro-CTA, diblock copolymers of poly[(HEMA-co-O300)-b-(DMAPS)] and poly[(HEMA-co-O300)-b-(LMA)] were grown via PISA in acetic acid. In order to maintain colloidal stability, it was necessary to conduct PISA of DMAPS at 10 wt% monomer, while LMA polymerizations maintained stability at 20 wt% monomer. Mnvs. conversion plots for both DMAPS and LMA show linear increases in molecular weight over the course of the polymerizations. Analysis of the molecular weight distributions revealed a progressive narrowing throughout the polymerization from an initial bimodal state. Copolymers of DMAPS and LMA were also synthesized over a large range of comonomer feed ratios. These materials show composition-dependent sizes in buffered solutions between 11 nm for the copolymer containing 80% by mol DMAPS to 75 nm for the copolymer containing 40 mol% DMAPS. PISA in acetic acid was then used to prepare copolymers of DMAPS with a range of hydrophobic polymerizable prodrug monomers as well as a polymerizable peptide macromonomer. The resultant copolymers had narrow molecular weight distributions and were readily soluble in saline solutions.


Materials Science and Engineering


This work was funded by the Defense Threat Reduction Agency (Grant #HDTRA1-13-1-0047).

Keywords and Phrases

Acetic acid; Block copolymers; Hydrophobicity; Living polymerization; Molecular weight; Molecular weight distribution; Monomers; Organic acids; pH; Polyethylene glycols; Polymethyl methacrylates; Self assembly, 2-hydroxyethyl methacrylate; Amphiphilic polymers; Degree of polymerization; Hydrophobic monomers; Lauryl methacrylate; Macrochain-transfer agents; Narrow molecular weight distributions; Poly(ethylene glycol) methyl ether methacrylate (PEG-MMA), Polymerization

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Article - Journal

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© 2016 Royal Society of Chemistry, All rights reserved.

Publication Date

01 Oct 2016