Flexible Polydimethylsiloxane-Based Porous Polyimide Films with an Ultralow Dielectric Constant and Remarkable Water Resistance AITranslate

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DOI：https://doi.org/10.1021/acsapm.9b00484

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This study aimed to prepare porous polyimide (PI) films with an ultralow dielectric constant and low water absorption by incorporating flexible polydimethylsiloxane (PDMS) segments and rigid adamantane groups into PI chains. Nanopores were then introduced by thermolysis of the thermally labile polyethylene glycol added into PI resin. Scanning electron micrographs showed that the porous PI films had uniform nanopores, which were regularly shaped with an average diameter of 237 ± 19 nm. The porous PI films further exhibited good thermal properties with T5% (temperature of 5% weight loss) of 411 °C in air and Tg (glass-transition temperature) of 299–301 °C because of the enhanced rigidity provided by adamantane. Outstanding dielectric properties and the dielectric constant value of 1.85 at 1 MHz were achieved for the films. The adamantane groups and PDMS segments have contributed to the lower polarizability, and the bulky adamantane groups and nanopores simultaneously provided enhanced free volumes. Moreover, the hydrophobicity of the adamantane groups and PDMS segments in PI induced substantial water resistance with the lowest water absorption of 1.15%. These properties indicated the high potential applications of porous PI films as interlevel insulation materials in next-generation microelectronic devices.