Plasma Surface Modification of Poly(Lactic-co-Ricinoleic Acid)Urethane: Chemical and Biological Characterizations

Abstract

Poly (ester urethane) s (PEUs) based on L-lactic acid (LA) and ricinoleic acid (RA), 1,6-hexamethylene diisocyanate (HMDI) were synthesized via polycondensation-chain extension reaction. Melt polycondensation reaction was carried out to produce the prepolymer poly (L-lactic acid-co-ricinoleic acid), with number average molecular weights (Mw) ranging from 3,000 to 10,000 g/mol. The weight ratio between LA with RA were 100:0, 95:5, 90:10, 80:20. The PEUs PEU100:0, PEU95:05, PEU 90:10 and PEU 80:20 were observed to be soft solids. Molecular weights increased after chain extension/coupling reaction with the diisocyanate, producing polymers with Mwranging from 60,000 to 115,000 g/mol. The production of poly (L-lactic acid-co-ricinoleic acid urethane) was verified by infrared (FTIR) and proton-nuclear magnetic (H1-NMR) spectroscopy. The poly (L-lactic acid) and the urethane groups are believed to form hard segment while the poly (ricinoleic acid) segment is the soft segment group. Moreover, oxygen plasma surface modification was also employed to alter the surface properties of the PEU samples Based on scanning electron microscopy (SEM), the surface roughens and hydroxyapatite mineralization were improved after the plasma treatment. The PEU materials were also found to be biocompatible with L929 mouse normal fibroblast cells.