Rapid Production of Ultralow Dielectric Constant Porous Polyimide Films via CO2-tert-Amine Zwitterion-Induced Phase Separation and Subsequent Photopolymerization

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• 作者：Kentaro Taki ; Kazunori Hosokawa ; Shota Takagi ; Hiroyuki Mabuchi ; Masahiro Ohshima
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：March 26, 2013
• 年：2013
• 卷：46
• 期：6
• 页码：2275-2281
• 全文大小：422K
• 年卷期：v.46,no.6(March 26, 2013)
• ISSN：1520-5835

文摘

Porous polymeric films are promising materials for the production of ultralow-dielectric constant materials. A high porosity polyimide thin film was prepared via the phase separation of a polyimide precursor in an N,N-dimethylacetamide (solvent)/2-(diethylamino)ethyl methacrylate/photoinitiator system. A novel technique involving high-pressure CO₂ (5 MPa) gas injection was used to form CO₂-2-(diethylamino)ethyl methacrylate zwitterion salt and induce the immediate phase separation and solvent droplet formation (within 60 s) of a wet precursor film on a metal substrate. The film was exposed to UV light through quartz windows for 30 s to polymerize the 2-(diethylamino)ethyl methacrylate while maintaining a constant CO₂ pressure. The cured thin film containing numerous pores with an average diameter of approximately 1 渭m 卤 1.0 渭m was treated at 320 掳C for 1 h under a continuous flow of nitrogen. The obtained film was 30 渭m thick and exhibited pores with an average diameter of approximately 1 渭m 卤 0.9 渭m. The ultralow-k level minimum relative dielectric constant for the optimal polyimide film was 1.536, and the porosity was 74% with open porous structure.