Abstract
Aerogels have presented a very high potential to be utilized as airborne nanoparticles' filtration media due to their nanoscale pore size and extremely high porosity. The filtering performance of aerogels, such as air permeability and filtration efficiency, is highly related to the configuration of aerogels' nanostructure assembly. However, as aerogel morphology is formed with respect to the intermolecular forces during the gelation stage, tailoring the aerogel nanostructure assembly is still a challenge. In this work, a novel strategy for tailoring polyimide aerogel nanostructure assembly is proposed by controlled disturbing of the intermolecular forces. From the results, the nanostructure assembly of the 4,4′-oxydianiline (ODA)–biphenyl-tetracarboxylic acid dianhydride (BPDA) polyimide aerogel is tailored to a uniform bimodal micro and nano porous structure. This was achieved by introducing the proper fraction of thermoplastic polyurethane (TPU) chains to the polyimide chains in the solution state and through a controlled process. The fabricated polyimide/TPU aerogels with bimodal morphology presented enhanced filtration performance, with 30% improved air permeability and reduced cell size of 3.51 nm over the conventional ODA–BPDA polyimide aerogels. Moreover, the fabricated bimodal aerogels present the reduced shrinkage, density, and effective thermal conductivity of 6.3% and 0.063 g cm−3, 28.7 mW m−1 K−1, respectively. Furthermore, the bimodal polyimide/TPU aerogels show the higher porosity of 96.5 vol% along with increased mechanical flexibility over the conventional polyimide aerogel with comparable backbone chemistry.
Highlights
Fast penetration of modern technology in all aspects of human life along with reduced lifespan of the products, such as electronics, resulted in increasing the number of production sites all over the world and speci cally in developing countries
Polyimide aerogel morphology is tailored to a very uniform bimodal micro and nanopores structure by disturbing the intermolecular forces through a controlled process. This is achieved by introducing the optimum molar fraction of the thermoplastic polyurethane (TPU)/NMP solution to the polyimide oligomers before the starting of the gelation stage
The morphology of ODA–biphenyl-tetracarboxylic acid dianhydride (BPDA), ODA– BPDA/10 wt% TPU, and ODA–BPDA 20 wt% TPU samples are presented in Fig. 2B, C, and D, respectively
Summary
Fast penetration of modern technology in all aspects of human life along with reduced lifespan of the products, such as electronics, resulted in increasing the number of production sites all over the world and speci cally in developing countries. Introducing the TPU solution to the ODA–BPDA polyimide chains resulted in the formation of a uniform micro size texture on the aerogel network structure.
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