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

Experimental conditions for the synthesis of poly(ε-caprolatone)-graft-poly(vinyl alcohol) (PCL-g-PVA) and poly(l-lactide)-graft-poly(vinyl alcohol) (PLLA-g-PVA) via a PVA/MgH2 macroinitiator were optimized. Heat stability of PVA (99% hydrolyzed) in l-lactide (L-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 13C NMR study showed that l-lactide was incorporated in graft chains as isotactic poly(l-lactide) without racemisation for 140–160 °C, up to 25 h, L-LA/PVA ratio in the range 3–12. Such synthesis using non-toxic 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 γCMC (46–63 mN m−1), hydrophilic to lipophilic balance HLB (Griffin definition 4–7), and also from cast films: surface energy γs (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.