Synthesis and surface characterization of functionalized polylactide copolymer microparticles

Microparticles of poly(lactide) (PLac) and its copolymers with the amino acids, serine (P(Lac-Ser)), and aspartic acid (P(Lac-Asp)), respectively, were synthesized using the solvent evaporation microemulsion technique. Poly(vinyl alcohol) (PVA) was added as a non-ionic surfactant to stabilize the particles. The particle sizes are in the range of 200 nm. The surface of the particles was characterized by FTIR transmission spectroscopy under evacuation at room temperature and at 200°C. Hydroxy groups originating from PVA exist on the surfaces of the particles and they were observed at 3506 cm-1. Free hydroxy groups originating from the serine residue pendant to the copolymer P(Lac-Ser) backbone were observed at 3396 cm-1. Also, free carboxylic acid groups pendant to the copolymer P(Lac-Asp) backbone, originating from the aspartic acid residue, were observed at 3387 cm-1. The appearance of the free hydroxy or carboxylic acid groups in the IR spectra also showed that these hydrophilic functional groups moved to the surface of the particles in the process of microemulsion.