RAFT polymerization of fatty acid containing monomers: controlled synthesis of polymers from renewable resources

Abstract

The incorporation of bio-renewable resources such as fatty acids into the polymer chain allows tailoring the properties of products, for their widespread applications. A series of methacrylate monomers with side-chain fatty acids (FAMA) were synthesized by esterification of 2-hydroxyethyl methacrylate (HEMA) and fatty acids, such as caprylic, capric, lauric, mysritic, palmitic and stearic acid. Consequent polymerization of FAMAs via reversible addition-fragmentation chain transfer (RAFT) gave side-chain fatty acid-containing well-defined polymers (PFAMA) with targeted molecular weights, narrow molecular weight distribution and precise chain-end functionality. The PFAMAs were subsequently used as macro-chain transfer agents (macro-CTA) for the polymerization of 2-(2-methoxyethoxy)ethyl methacrylate (MEO₂MA) to obtain block copolymers. Homopolymers with fatty acid pendants display crystalline behaviour depending on the chain length of the fatty acids, evidenced by differential scanning calorimetry (DSC), polarized optical microscopy, small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) techniques.