Mosanenzadeh Shahriar Ghaffari, Saadatnia Zia, Karamikamkar Solmaz, Park Chul B, Naguib Hani E
Department of Mechanical and Industrial Engineering, University of Toronto Toronto Ontario M5S 3G8 Canada
Department of Materials Science and Engineering, University of Toronto Toronto Ontario M5S 3G8 Canada.
RSC Adv. 2020 Jun 16;10(39):22909-22920. doi: 10.1039/d0ra03907a.
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, 28.7 mW m K, 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.
气凝胶因其纳米级孔径和极高的孔隙率，在用作空气中纳米颗粒过滤介质方面展现出了很高的潜力。气凝胶的过滤性能，如透气率和过滤效率，与气凝胶纳米结构组件的构型高度相关。然而，由于气凝胶形态是在凝胶化阶段相对于分子间力形成的，定制气凝胶纳米结构组件仍然是一项挑战。在这项工作中，通过对分子间力进行可控干扰，提出了一种定制聚酰亚胺气凝胶纳米结构组件的新策略。结果表明，4,4'-二氨基二苯醚（ODA）-联苯四甲酸二酐（BPDA）聚酰亚胺气凝胶的纳米结构组件被定制为均匀的双峰微米和纳米多孔结构。这是通过在溶液状态下将适当比例的热塑性聚氨酯（TPU）链引入聚酰亚胺链并通过可控过程实现的。制备的具有双峰形态的聚酰亚胺/TPU气凝胶展现出增强的过滤性能，与传统的ODA-BPDA聚酰亚胺气凝胶相比，透气率提高了30%，孔尺寸减小至3.51纳米。此外，制备的双峰气凝胶收缩率、密度降低，有效热导率分别为6.3%和0.063 g/cm、28.7 mW/(m·K)。此外，与具有可比主链化学结构的传统聚酰亚胺气凝胶相比，双峰聚酰亚胺/TPU气凝胶孔隙率更高，达96.5 vol%，同时机械柔韧性增强。
