Versatile Synthesis of Functional Biodegradable Polymers by Combining Ring-Opening Polymerization and Postpolymerization Modification via Michael-Type Addition Reaction

Various functional biodegradable polymers were readily prepared based on novel cyclic carbonate monomers, acryloyl carbonate (AC) and methacryloyl carbonate (MAC), by combining ring-opening polymerization (ROP) and Michael-type conjugate addition. AC and MAC monomers were synthesized in four straightforward steps from 1,1,1-tris(hydroxymethyl)ethane with good overall yields (ca. 40%). AC and MAC were able to copolymerize with epsilon-caprolactone (epsilon-CL) and D,L-lactide (LA) in toluene at 110 degrees C using stannous octoate as a catalyst yielding biodegradable copolymers with controlled (meth)acryloyl functional groups and molecular weights. The acryloyl groups were amenable to the Michael-type conjugate addition with varying thiol-containing molecules Such as 2-mercaptoethanol, 3-mercaptopropanoic acid, cysteamine, cysteine, and arginine-glycine-aspartic acid-cysteine (RGDC) peptide under mild conditions, to provide biodegradable materials with vastly different functionalities (e.g., hydroxyl, carboxyl, amine, amino acid, and peptides) and properties (e.g., hydrophilicity, cell adhesion). Notably, 100% functionalization was achieved with 2-mercaptoethanol, cysteamine and cysteine. Initial Cell Culture Studies demonstrated enhanced cell adhesion and growth oil films containing functional RGDC peptides as compared to those of the parent copolymer. Therefore, combination of ROP and Michael-type Conjugate addition provides a versatile access to diverse types of functional biodegradable materials.