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首页> 外文期刊>International journal of planning and scheduling >Influence of Swelling in scCO_2 of Thin Polyimide Films on Their Microstructure to Obtain Polymer Dielectrics for Microelectronics and Heat-Resistant Gas Separation Membranes
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Influence of Swelling in scCO_2 of Thin Polyimide Films on Their Microstructure to Obtain Polymer Dielectrics for Microelectronics and Heat-Resistant Gas Separation Membranes

机译：Influence of Swelling in scCO_2 of Thin Polyimide Films on Their Microstructure to Obtain Polymer Dielectrics for Microelectronics and Heat-Resistant Gas Separation Membranes

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Here, the swelling with supercritical carbon dioxide (sc-CO_2) of thin films of polyimides having various structures was investigated. It was shown that the degree of swelling is significantly influenced by the solvent which was used for the synthesis of those polyimides, by the solvent which was used for the preparation of thin films and by the conformational rigidity of the polymers. The presence of hexafluoroisopropylidene groups in the main chain of a polymer prevents its swelling with sc-CO_2. It is shown that the degree of increase of the free volume in the polymer matrix during swelling in sc-CO_2 also determined experimental conditions (pressure, temperature and the pressure relief rate). Transport parameters such as permeability and selectivity coefficients measured before and after treatment with sc-CO_2 increased from 16 to 168 and from 5 to 49, respectively. The greatest increase in the free volume was 257 of the initial value during rapid pressure relief. This led to the formation of foams and reduction of the dielectric constant even below 1.5.

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