Preparation and Characterization of Fluorine-Containing Polybenzoxazole Composite Films including Graphene Oxide as a Reinforcing Material

Abstract

The fluorine-containing polyhydroxyamide (F-75-PHA) was synthesized by using low-temperature solution polycondensation of 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BAHHFP, 75 mol%) and 3,3′-dihydroxybenzidine (DHB, 25 mol%) with terephthaloyl chloride (TPC) in N-methyl-2-pyrrolidinone (NMP) without metal salts. The F-75-PBO (polybenzoxazole)/GO (graphene oxide) composite films with different GO contents (0.01, 0.1, and 1.0 wt%, respectively) were prepared by heat-treatment of their precursors (F-75-PHA/GO composite films), and the effects of reinforcing material (GO) on the structural, thermal, and mechanical properties of them were studied systemically. FE-SEM images that the F-75-PBO matrix and GO sheets had a superior hydrogen bonding interaction and formed a three-dimensional (3D) network structure in composite films having a great bendability. FT-IR spectra indicated that the incorporation of GO in composite films could be reacting hydroxyl (−OH) groups on F-75-PHA matrix to carboxyl (−COOH) and/or −OH groups in GO sheets, and thus the O-H stretching peak (23.8 %) for F-75-PHA/GO-0.1 composite film mostly disappeared in comparison with that (100 %) of F-75-PHA film. DSC heating curves revealed that the thermal cyclization temperature (Tc) of the F-75-PHA/GO composite films decreased with an increment of GO content. Interestingly, for F-75-PHA/GO-0.1 composite film, the Tc decreased by up to 254 °C. However, despite the outstanding reinforcing effect of GO sheets, an interesting phenomenon was confirmed that 3D network structure including an excellent hydrogen bonding interaction did not largely influence the mechanical properties of F-75-PBO/GO composite films.