Nanomechanical characterization of copolymers based on PLLA and PEO/PPO blocks

L. M. D. LOIOLA; FASCE, L. A.; M.I. FELISBERTI; P.M. FRONTINI

Congreso; Congreso Internacional de Metalurgia y Materiales SAM-CONAMET / IBEROMAT 2014; 2014

Poly(L-lactide) (PLLA) is a biocompatible polyester recognized by its use in biomaterials field, mainly as polymer biomedical devices. However, its hydrophobic nature and unsatisfactory mechanical properties represent drawbacks to soft tissue engineering applications. This limitation can be overcome by the copolymerization of L-lactide with hydrophilic polyether blocks. Amphiphilic copolymers with PLLA hydrophobic blocks attached to hydrophilic polyether blocks such as poly(ethylene oxide) (PEO) and copolymers of ethylene and propylene oxides were synthesized. Thereby, a series of copolymers containing soft and hard blocks were achieved by ring-opening polymerization (ROP) of the cyclic monomer L-lactide with polyethers as macroinitiators. Nanoindentation emerges as a powerful technique to assess mechanical properties of biomaterials at the nano or submicron scale. In this work, nanoindnetation experiments were carried out to evaluate elastic modulus and hardness of the synthesized materials. The hardness of PLLA-PEO-PLLA resulted comparable to PLLA homopolymer, although its modulus was reduced from 5 to 1 GPa due to copolymerization with PEO. In the copolymers, the modulus and hardness depended on blocks composition and orientation, and on degree of crystallinity. Copolymerization arises as PLLA stiffness modifier regarding soft tissue engineering applications.