Ductile Polyimide/Reduced Graphene Oxide Nanohybrid Films with Porous Structure Fabricated by a Green Hydrogel Strategy
mediaposted on 22.03.2019, 00:00 by Zhao Chen, Faqin Tong, Dandan Zhu, Xuemin Lu, Qinghua Lu
Polyimide/inorganics hybrid films fabricated by conventional approaches, including an in situ polymerization method, the sol–gel process, and a solution blending method, have a dramatic drop in malleability. In this work, a hydrogel strategy for preparing ductile polyimide/reduced graphene oxide (PI/rGO) nanohybrid films with internal porous structures has been proposed. The hydrogel strategy involved two steps. The polyamide acid carboxylate/GO (PAAC/GO) films were first prepared by tape casting, followed by a gelation process of the PAAC/GO aqueous solution; the PI/rGO films were then obtained after an imidization reaction of the PAAC/GO films. Interestingly, in this strategy, the PAA chains tended to self-assemble into microdomain crystalline structures assisted by their interactions with water, as revealed by XRD and Raman spectroscopy. The present PI/rGO films display more uniform microstructures, without aggregation of the rGO nanosheets. Furthermore, they exhibited an enhanced toughness property, with a high elongation at break of 37–55%. In addition, their dielectric property is more stable and less frequency-dependent due to the internal porous structure. This hydrogel strategy would appear to be a promising candidate for fabricating hybrid PI–inorganic composite materials, even other hybrid organic/inorganic composite materials with specific features.