Main-chain polybenzoxazine nanofibers via electrospinning

Here we report the successful production of nanofibers from main-chain polybenzoxazines (MCPBz) via electrospinning without using any other carrier polymer matrix. Two different types of MCPBz (PBA-ad6 and PBA-ad12) were synthesized by using two types of difunctional amine (1,6-diaminohexane and 1,12-diaminododecane), bisphenol-A, and paraformaldehyde as starting materials through a Mannich reaction. H-1 NMR and FTIR spectroscopy studies have confirmed the chemical structures of the two MCPBz. We were able to obtain highly concentrated homogeneous solutions of the two MCPBz in chloroform/ N,N-dimethylformamide (DMF) (4:1, v/v) solvent system. The electrospinning conditions were optimized in order to produce bead-free, uniform and continuous nanofibers from these two MCPBz by varying the concentrations of PBA-ad6 (30-45%, w/v) and PBA-ad12 (15-20%, w/v) in chloroform/DMF (4:1, v/v). The bead-free fiber morphology was evidenced under SEM imaging when PBA-ad6 and PBA-ad12 were electrospun at solution concentration of 40% and 18% (w/v), respectively. The nanofibrous mats of MCPBz were obtained as free-standing material, yet, PBA-ad12 mat was more flexible than and PBA-ad6 mat. Furthermore, the curing studies of these MCPBz nanofibrous mats were performed to obtain cross-linked materials. (C) 2013 Elsevier Ltd. All rights reserved.