Toward the goal of developing degradable polycationic materials with tunable backbone charge densities and hydrophilicities, we report the optimized syntheses and polymerization activities of a series of N-Boc-protected amino acidO-vinyl ester (BAAVE) monomers derived from Boc-protected glycine, alanine, valine, and proline. The homopolymerization and copolymerization behaviors of these monomers under thermally initiated conventional free radical polymerization conditions are studied. By conducting copolymerizations of (N-tert-butoxycarbonyl)glycine vinyl ester (BGVE) with vinyl acetate (VAc) at various feed ratios and by analyzing the compositions of the resulting polymers produced at 88 °C using 1,1′-azobis(cyclohexane-1-carbonitrile) (V-40) initiation, we find that the reactivity ratios are rBGVE = 1.61 ± 0.12 and rVAc = 0.82 ± 0.07. Treatment of poly(VAc-co-BAAVE) with neat CF3COOH selectively unmasks the Boc-protected amine functionalities to furnish cationic poly(VAc-co-AAVE·CF3COOH) copolymers. Alternatively, treatment of these random copolymers with methanolic HCl results in the complete hydrolysis of both the Boc-protecting groups as well as the acetate esters, enabling access to well-defined, hydrophilic, polycationic amino acid ester-functionalized poly(vinyl alcohol) materials.
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