Environment-friendly synthesis of amphiphilic polyester-graft-poly(vinyl alcohol)

Experimental conditions for the synthesis of poly(epsilon-caprolatone)-graft-poly(vinyl alcohol) (PCL-g-PVA) and poly(t-lactide)-graft-poly(vinyl alcohol) (PLLA-g-PVA) via a PVA/MgH2 macroinitiator were optimized. Heat stability of PVA (99% hydrolyzed) in t-lactide CL-LA) melt was studied by DSC, TGA to lower the reaction temperature and time in order to avoid degradation. Thus, no degradation of copolymers occurred and C-13 NMR study showed that t-lactide was incorporated in graft chains as isotactic poly(t-lactide) without racemisation for 140-160 degrees C, up to 25 h, L-LA/PVA ratio in the range 3-12. Such synthesis using nontoxic catalyst and reactants in a solvent-free medium can be described as environment-friendly. Amphiphilic behavior of copolymers was studied in aqueous solution according to their chemical structures: critical micelle concentration CMC (0.03-0.5 g L-1), average diameter of micelles (80-150 nm), surface tension ycrvic (46-63 mN m(-1)), hydrophilic to lipophilic balance HLB (Griffin definition 4-7), and also from cast films: surface energy Vs (36-50 mJ m(-2)). This environment-friendly process is suitable for the use of,graft PVA copolymers in biomedical area for investigations under micelle applications. (C) 2013 Elsevier Ltd. All rights reserved.