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From Monomers to a Lasagna-like Aerogel Monolith: An Assembling Strategy for Aramid Nanofibers
ACS Nano ( IF 15.8 ) Pub Date : 2019-07-09 00:00:00 , DOI: 10.1021/acsnano.9b01955 Chunjie Xie 1 , Lianyuan He 1 , Yifei Shi 1 , Zhao-Xia Guo 1 , Teng Qiu 2 , Xinlin Tuo 1
ACS Nano ( IF 15.8 ) Pub Date : 2019-07-09 00:00:00 , DOI: 10.1021/acsnano.9b01955 Chunjie Xie 1 , Lianyuan He 1 , Yifei Shi 1 , Zhao-Xia Guo 1 , Teng Qiu 2 , Xinlin Tuo 1
Affiliation
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The manipulation of nanobuilding blocks into a 3D macroscopic monolith with ordered hierarchical structures has been much desired for broad and large-scale practical applications of nanoarchitectures. In this paper, we demonstrate a fully bottom-up strategy for the preparation of aramid aerogel monoliths. The process starts from the synthesis of poly(p-phenylene terephthalamide) (PPTA) through the polycondensation of p-phenylenediamine and terephthaloyl chloride, with the assistance of a nonreactive dispersing agent (polyethylene glycol dimethyl ether), which helps the dispersal of the as-synthesized PPTA in an aqueous medium for the formation of p-aramid nanofibers (ANF). Then the vacuum-assisted self-assembly (Vas) technique is skillfully connected with the ice-templated directional solidification (I) technique, and the combined VasI method successfully tailors the self-assembly of ANF to transform the 1D nanofibers into a 3D aerogel monolith with a specific long-range aligned, lasagna-like, multilaminated internal structure. The study of the aerogel microstructure revealed the dependence of the lamina orientation on the direction of the freezing front of ice crystals. This direction should be parallel to the deposition plane of the Vas process if a long-range aligned lamellar structure is desired. The anisotropy of the multilaminated aerogel was proven by the different results in the radial and axial directions in the compression and thermal conductivity tests. As a kind of organic aerogel, the ANF monolith has typical low density, high porosity, and low thermal conductivity. Additionally, the ANF monolith exhibits high compressive stress and excellent thermal stability. Considering its high performance and facile preparation process, potential applications of the ANF aerogel monolith can be expected.
中文翻译：
从单体到千层面的气凝胶单块：芳纶纳米纤维的组装策略
对于纳米结构的广泛和大规模的实际应用，已经非常需要将纳米构建块操纵为具有有序的层次结构的3D宏观整体结构。在本文中，我们演示了制备芳族聚酰胺气凝胶整体料的完全自下而上的策略。从合成的过程开始聚（p亚苯基对苯二甲酰胺）（PPTA）通过缩聚p苯二胺和对苯二甲酰氯，与非反应性分散剂的帮助下（聚乙二醇二甲醚），这有助于的疏散作为在水介质中合成PPTA以形成p-芳族聚酰胺纳米纤维（ANF）。然后将真空辅助自组装（Vas）技术与冰样定向凝固（I）技术巧妙地结合在一起，并且结合的VasI方法成功地将ANF的自组装量身定制，将一维纳米纤维转变为3D气凝胶整体具有特定的远程排列，千层面样，多层内部结构。对气凝胶微观结构的研究揭示了薄片取向与冰晶冻结前沿方向的关系。如果需要长距离排列的层状结构，则该方向应平行于Vas工艺的沉积平面。多层气凝胶的各向异性通过压缩和热导率测试在径向和轴向上的不同结果得到证明。作为一种有机气凝胶，ANF整料具有典型的低密度，高孔隙率和低导热率。此外，ANF整体材料还显示出高压缩应力和出色的热稳定性。考虑到其高性能和简便的制备过程，可以预期ANF气凝胶整料的潜在应用。
更新日期：2019-07-09
中文翻译：
从单体到千层面的气凝胶单块：芳纶纳米纤维的组装策略
对于纳米结构的广泛和大规模的实际应用，已经非常需要将纳米构建块操纵为具有有序的层次结构的3D宏观整体结构。在本文中，我们演示了制备芳族聚酰胺气凝胶整体料的完全自下而上的策略。从合成的过程开始聚（p亚苯基对苯二甲酰胺）（PPTA）通过缩聚p苯二胺和对苯二甲酰氯，与非反应性分散剂的帮助下（聚乙二醇二甲醚），这有助于的疏散作为在水介质中合成PPTA以形成p-芳族聚酰胺纳米纤维（ANF）。然后将真空辅助自组装（Vas）技术与冰样定向凝固（I）技术巧妙地结合在一起，并且结合的VasI方法成功地将ANF的自组装量身定制，将一维纳米纤维转变为3D气凝胶整体具有特定的远程排列，千层面样，多层内部结构。对气凝胶微观结构的研究揭示了薄片取向与冰晶冻结前沿方向的关系。如果需要长距离排列的层状结构，则该方向应平行于Vas工艺的沉积平面。多层气凝胶的各向异性通过压缩和热导率测试在径向和轴向上的不同结果得到证明。作为一种有机气凝胶，ANF整料具有典型的低密度，高孔隙率和低导热率。此外，ANF整体材料还显示出高压缩应力和出色的热稳定性。考虑到其高性能和简便的制备过程，可以预期ANF气凝胶整料的潜在应用。
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