Meta-aramid film with both flexibility and strength: Combined effect of aromatic ether bond and micro-branched structure

Abstract

Developing Meta-aramid materials that combine flexibility and strength will greatly expand their application fields. In previous work, it was demonstrated that aromatic ether bonds can contribute to improving flexibility. In addition, micro-branched chain structures can reduce intermolecular forces by increasing fractional free volume, while newly formed hydrogen bonding can maintain polymer strength. Therefore, two flexible polymers were obtained by incorporating 4,4′-diaminodiphenyl ether (ODA) and 4,4′-oxybis [3-(trifluoromethyl)benzenamine] (OTB) to the molecular chains, respectively, and flexible films were prepared by a combination of solution casting and dry-wet processing methods. By studying the properties of copolymer films with 10% ODA and 10% OTB added, it was found that they can maintain thermal stability and mechanical strength while improving the flexibility of the films. The AFM results visually showed that the DMT modulus of the modified films decreased at the micro level and DMA indicated that the introduction of ODA and OTB can shorten the molecular relaxation time, which reflected the improvement of molecular chain flexibility. Through molecular dynamics simulations, the differences were compared in molecular chain conformation, mean square displacement and hydrogen bonding after the introduction of ODA and OTB and the combined mechanism of aromatic ether bonds and CF3 side groups was confirmed in improving flexibility and maintaining mechanical strength.