Polyimide (PI) foams possess excellent mechanical properties and high-temperature resistance, which present significant utility in the aerospace, transportation, and microelectronics industries. The microstructure of PI foam, specifically the pore size and porosity, significantly influences its physical and mechanical properties. However, achieving both high porosity and small pore size simultaneously is greatly challenging for PI foams, especially via the foaming method. Here, we report PI foams with mean pore size of 98.1 μm and porosity of 92 % using a one-step scrape foaming method. The scraping thickness is found to be key to adjusting the pore size of the foam due to the interface effect in the initial stage, and maintaining optimal air pressure and low temperature allows slow bubble growth without bursting or merging, resulting in PI foams with high porosity and small pore size. The PI foam we fabricated exhibits excellent thermal insulating performance, with a low thermal conductivity of 20 mW/m∙K. The scrape foaming method provides an efficient and low-cost strategy for the preparation of PI foams with a tunable porous structure and is expected to find a variety of applications in thermal insulation and environmental protection.

中文翻译：

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通过刮擦发泡制备的微米级高孔隙率聚酰亚胺泡沫，用于隔热


聚酰亚胺 （PI） 泡沫具有优异的机械性能和耐高温性，在航空航天、运输和微电子行业中具有重要用途。PI 泡沫的微观结构，特别是孔径和孔隙率，会显著影响其物理和机械性能。然而，对于 PI 泡沫来说，同时实现高孔隙率和小孔径是极具挑战性的，尤其是通过发泡方法。在这里，我们报告了使用一步刮擦发泡方法的平均孔径为 98.1 μm、孔隙率为 92% 的 PI 泡沫。由于初始阶段的界面效应，发现刮擦厚度是调整泡沫孔径的关键，保持最佳气压和低温可以使气泡缓慢生长而不会爆裂或合并，从而产生孔隙率高、孔径小的 PI 泡沫。我们制造的 PI 泡沫具有出色的隔热性能，导热系数低至 20 mW/m∙K。刮擦发泡方法为制备具有可调多孔结构的 PI 泡沫提供了一种高效且低成本的策略，有望在隔热和环境保护方面得到多种应用。