Covalent modified graphene oxide in biopolymer scaffold: dispersion and interfacial bonding

Abstract

Graphene oxide (GO) has drawn more attention as reinforcement in polymer by reason of excellent mechanical properties. While its aggregation and weak interfacial bonding to polymer matrix will deteriorate positive effect. In this study, GO was modified with 3-Aminopropyltriethoxysilane (APTES) to facilitate its dispersion and improve interfacial bonding with polyglycolide (PGA) in scaffold fabricated by means of selective laser sintering (SLS). To be specific, -OH groups of hydrolyzed APTES formed covalent bonding with -OH groups of GO, which introduced numerous long alkyl chains and -NH2 groups on GO. The long alkyl chains could generate steric hindrance effect against GO aggregation, while the -NH2 groups could interact with the -COOH groups of PGA and thus enhance interfacial bonding between GO and PGA. The results suggested that introduction of APTES led to a better exfoliation of GO with a thickness of about 1.52 nm, which was beneficial to uniform dispersion of GO in matrix. GO nanosheets adhered to polymer matrix with much wire-drawing on the fracture surface, and the scaffold possessed improved thermal stability, indicating the good interfacial bonding. Tensile and compressive strength of scaffold loading 0.75 wt% APTES modified GO improved by 112% and 54%, respectively, compared with scaffold without modification. In addition, cell experiments in vitro manifested that scaffold possessed benign cytocompatibility for cell adhesion and growth, providing important benefits related to bone regeneration.