Preparation and Characterization of Highly Cross-Linked Polyimide Aerogels Based on Polyimide Containing Trimethoxysilane Side Groups
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- 作者：Xueliang Pei ; Wentao Zhai ; Wenge Zheng
- 刊名：Langmuir
- 出版年：2014
- 出版时间：November 11, 2014
- 年：2014
- 卷：30
- 期：44
- 页码：13375-13383
- 全文大小：551K
- ISSN：1520-5827
文摘
In this study, highly cross-linked and completely imidized polyimide aerogels were prepared from polyimide containing trimethoxysilane side groups, which was obtained as the condensation product of polyimide containing acid chloride side groups and 3-aminopropyltrimethoxysilane. After adding water and acid catalyst, the trimethoxysilane side groups hydrolyzed and condensed one another, and a continuous increase in the complex viscosities of the polyimide solutions with time was observed. The formed polyimide gels were dried by freeze-drying from tert-butyl alcohol to obtain polyimide aerogels, which consisted of a three-dimensional network of polyimide fibers tangled together. By varying the solution concentration of the polyimide containing trimethoxysilane side groups, polyimide aerogels with different densities (ranging from 0.19 to 0.42 g/cm3) were obtained. The resulting polyimide aerogels had small pore diameter (ranging from 20.7 to 58.3 nm), high surface area (ranging from 310 to 344 m2/g), high 5% weight loss temperature in air (at about 440 掳C), and an excellent mechanical property. In addition, the glass transition temperature (349 掳C) of the polyimide aerogels was much higher than that (210 掳C) of the corresponding linear polyimide. So, even after being heated at 300 掳C for 30 min, the porous structure of the polyimide aerogels was not completely destroyed.