Main-chain polybenzoxazine nanofibers via electrospinning

Abstract

a b s t r a c tHere 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.1 H 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 (30e45%, w/v) and PBA-ad12 (15e20%, w/v) in chloroform/DMF (4:1, v/v). The bead-free fiber morphology was evidenced under SEM imaging when PBA-ad6 and PBAad12 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.

Cross-linked main-chain polybenzoxazine nanofibers by photo and thermal curing; stable at high temperatures and harsh acidic conditions

“…First example of the cross-linking of polybenzoxazine-based nanofibers by directly thermal curing was given by Li and co-workers [29]. Initially, they produced nanofibers from MCPBz synthesized by using 4,4 0 -diaminophenylether and bisphenol-A, and then they were able to obtain cross-linked MCPBz nanofibers by thermal curing at 240 C for 3 h. On the contrary, our previous study demonstrated that nanofibers produced by MCPBz which based on the bisphenol-A and diamines with long aliphatic chains (1,12diaminododecane and 1,6-diaminohexane) have not shown resistance to the heat treatment during the thermal curing and nanofibers lost the fiber morphology at low temperatures around 75e100 C [28]. Presumably, 4,4 0 -diaminophenylether provided more rigid structure to the MCPBz nanofibers compared with 1,12diaminododecane and 1,6-diaminohexane, hence, the melting temperature of the nanofibers obtained from the former one is much higher than the others.…”

“…for various applications. On the other hand, electrospinning of nanofibers from polybenzoxazine resins is a new concept and electrospinning of MCPBz resins without using additional polymeric matrices was first reported recently by our group [28].…”

Polybenzoxazine-Based Nanofibers by Electrospinning

“…Ertas and Uyar reported the first study to produce bead-free and uniform polybenzoxazine nanofibers from MCPBz without using carrier polymeric matrices [75]. Initially, two different types of MCPBz (poly(BA-dh) main and poly(BA-dd) main ) were synthesized by using two types of difunctional amine (1,6-diaminohexane and 1,12diaminododecane), BA, and paraformaldehyde as starting materials through a Mannich reaction.…”

“…Representative SEM images and corresponding fiber diameter distributions with average fiber diameter (AFD) of the electrospun nanofibers obtained from solutions of poly(BA-dh) main (A, B) 30%, (C, D) 35%, (E, F) 40%, and (G, H) 45%. Inset shows magnified view of a typical region[75].FIG. 22 Representative SEM images and corresponding fiber diameter distributions of the electrospun nanofibers obtained from solutions of poly(BA-dd) main (A, B) 15%, (C, D) 18%, and (E, F) 20%.…”

Fabrication of Thermally Crosslinked Hydrolyzed Polymers of Intrinsic Microporosity (HPIM)/Polybenzoxazine Electrospun Nanofibrous Membranes

“…These properties enable the production of high‐performance composite materials . Thus, immense research has been conducted on different forms of polybenzoxazines including bulk, film, aerogel, membrane, and nanofibers . However, far too little attention has been paid to the incorporation of polybenzoxazine into polymeric nanofibers …”