Synthesis of biodegradable liquid-core microcapsules composed of isocyanate functionalized poly(ε-caprolactone)-containing copolymers

Abstract A combination of reversible deactivation radical polymerization (RDRP), isocyanate chemistry, and a convenient drying process via spray drying is employed to fabricate powder-form biodegradable liquid-core microcapsules. Two different molecular weight α,ω-poly(e caprolactone) RDRP macroinitiators were first prepared through esterification to obtain the degradable α-halo ester initiators. Subsequently, poly(benzyl methacrylate-co-isocyanatoethyl methacrylate) (P(BnMAa-co-IEMb)) copolymers were synthesized from the RDRP macroinitiators using a copper(0)-mediated polymerization system at ambient temperature. By controlling the macroinitiator to monomer feeding ratio from 1:50 to 1:100, the resultant copolymers had number average molecular weights (Mn) in the range of 7900–17800 g mol−1 with dispersities (Đ) of 1.42-1.52. Afterward, the isocyanate-containing copolymers were employed in the fabrication of particles via interfacial polymerization, followed by a water removal process using spray drying. All polymers and particles were thoroughly characterized using a range of spectroscopic, chromatographic and microscopy analyses.