聚酰亚胺
材料科学
聚合物
热稳定性
玻璃化转变
部分
收缩率
BPDA公司
热分解
气凝胶
芴
复合材料
高分子化学
化学工程
有机化学
图层(电子)
化学
工程类
作者
Rocco P. Viggiano,Jarrod C. Williams,David A. Schiraldi,Mary Ann B. Meador
标识
DOI:10.1021/acsami.6b15440
摘要
With unique advantages over inorganic aerogels including higher strengths and compressive moduli, greater toughness, and the ability to be fabricated as a flexible thin film, polymer aerogels have the potential to supplant inorganic aerogels in numerous applications. Among polymer aerogels, polyimide aerogels possess a high degree of high thermal stability as well as outstanding mechanical properties. However, while the onset of thermal decomposition for these materials is typically very high (greater than 500 °C), the polyimide aerogels undergo dramatic thermally induced shrinkage at temperatures well below their glass transition (Tg) or decomposition temperature, which limits their use. In this study, we show that shrinkage is reduced when a bulky moiety is incorporated in the polymer backbone. Twenty different formulations of polyimide aerogels were synthesized from 3,3,′4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-oxidianiline (ODA) or a combination of ODA and 9,9′-bis(4-aminophenyl)fluorene (BAPF) and cross-linked with 1,3,5-benzenetricarbonyl trichloride (BTC) in a statistically designed study. The polymer concentration, n-value, and molar concentration of ODA and BAPF were varied to demonstrate the effect of these variables on certain properties. Samples containing BAPF showed a reduction in shrinkage by as much as 50% after aging at elevated temperatures for 500 h compared to those made with ODA alone.
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