The effect of surface modification of zeolite 4A on the physical and electrical properties of copolyimide hybrid films

• Unmodified/modified zeolite 4A doped copolyimide hybrid films were prepared.
• Amino silane surface treatment of zeolite improved the thermal and mechanical properties.
• Intramolecular/intermolecular hydrogen bonding and covalent bonding affected dielectric properties.
• Dielectric constant values decreased with increasing modified zeolite content.

In the present work a series of copolyimide (PI) hybrid films that contained zeolite 4A were prepared and the effect of surface modification of zeolite on physical and electrical properties of hybrid films was investigated. (3-aminopropyl)trimethoxysilane was used to modify the zeolite surface. DC conductivity measurements were performed at room temperature and the capacitance was measured in the temperature range of 295–458 K in a vacuum ambient in the dark. The surface modification of zeolite contributed to thermal, mechanical and hydrophobicity properties of PI hybrid films. Morphological investigation also indicated that the interface between polyimide and zeolite phases improved when modified zeolite was used. Dielectric measurements revealed that dielectric constant of the films increased with increasing temperature and decreased with increasing frequency. Variation in dielectric constants of zeolite-doped and modified zeolite-doped films showed opposite behaviors with zeolite loading, due to different interaction types between polymer and zeolite.

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