Functional polyhedral oligomeric silsesquioxane reinforced poly(lactic acid) nanocomposites for biomedical applications

Polyhedral oligomeric silsesquioxane reinforced poly (L-lactic acid) nanocomposites (PLLA/POSS) were prepared to overcome the insufficient mechanical properties of PLLA. In order to improve the compatibility between the nanofillers and matrix, PLLA chains were grafted onto the POSS nanoparticles via microwave-assisted ring opening polymerization (ROP). Herein, a series of interface-modified polyhedral oligomeric silsesquioxane (POSS-(PLLA)(32)) nanoparticles with various PLLA tail lengths were synthesized and the influence of the structure and additional amount of POSS nanoparticles on the properties of PLLA based nanocomposites were studied. POSS nanoparticles exhibit effective nucleation activity and lead to a significant improvement in the mechanical strength, thermal stability and biocompatibility of the resulting nanocomposites. The addition of 6 wt% POSS-(PLLA)(32) 600 shows the optimal mechanical properties owing to has the longest PLLA tail length on POSS core, which possesses the optimal interfacial compatibility between POSS nanoparticles and PLLA. The Young's modulus improved by 57% and the tensile strength increased by 26.5% compared with neat PLLA. Moreover, the introduction of POSS nanoparticles lead to a porous fiber structure when processed by electrospinning and the nanofibrous scaffold effectively promoted cells adhesion and spreading. These results demonstrate the potential applications of the PLLA/POSS nanocomposites in tissue engineering and regenerative medicine.