Hydrolytic behavior of poly(lactic acid) films with different architecture modified by poly(dodecafluorheptyl methylacrylate)

Poly(lactic acid) (PLA) coated with poly(dodecafluorheptyl methylacrylate) (PFA), namely PLA-coat-PFA, and PLA blended with PFA, namely PLA-blend-PFA, together with neat PLA were subjected in 40 C water for 100 days to investigate the hydrolytic behavior of the materials with different architectures. The water diffusion rate and hydrolytic behavior were studied by means of water absorption test, morphology observation, monitor of mass loss, pH measurement, thermal analysis and molecular weight determination. The results show that (1) the water permeation in PLA can be hindered by coating with PFA, while water absorption can be enhanced by blending with PFA because the gaps between PLA and PFA, resulting from poor interaction between the two phases, reduce the penetration depth; (2) the neat PLA and PLA-coat-PFA undergo heterogeneous degradation while PLA-blend-PFA behaves as homogeneous degradation, and the degradation rate follows the order: PLA > PLA-blend-PFA > PLA-coat-PFA; (3) coating and blending PFA with PLA can both delay the hydrolytic degradation of PLA by hindering water permeation and decreasing the autocatalysis of the hydrolytic products, respectively. (C) 2014 Elsevier Ltd. All rights reserved.