Reduction of dielectric constant by nanovoids formed through chemical treatment on silica crosslinked polyimide and its effect on properties

Abstract

In this study, 2,7‐diamino‐9‐fluorenol (DAF) has been introduced to bond silica to the main chain of the polyimide (PI) copolymer. DAF contains a hydroxyl group that could covalently bond with silica particles. 4,4′‐(Hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 4,4′‐oxydianiline (4,4′‐ODA) have been used as monomers to form a copolymer with DAF. The variation of silica content was controlled as 5%, 7.5, 10, 12.5 wt %. Variation in silica content contributes to the formation of various size (100–410 nm) of macroporous voids after hydrofluoric acid (HF) treatment. HF etching process was introduced to dissolve the silica and form voids in the structure of PI copolymer films. Compared with conventional PI films, air voids that were formed in the PI copolymer film reduced the dielectric from 4.40 to 1.86. The reduction in the dielectric constants can be explained in terms of creating silica particles that increase the presence of air voids after HF treatment. The thermal stability was stable up to 500 °C and the modulus change was confirmed with a dynamic mechanical analysis (DMA) to evaluate the effect of silica on thermal and mechanical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45982.

Effect of nanosilica with different interfacial structures on mechanical properties of polyimide/SiO2 composites

“…It is the reason that as the radius of the embedded nanoparticle in the nanocomposites increases, the number of atoms in the surrounding PI consequently increases and, thus, a larger nanoparticle in the nanocomposites can have a greater number of nonbonding pairs . High interaction energy means the particles possess perfect dispersity and satisfactory adhesive in PI matrix, and it can improve the compatibility between PI and SiO 2 . Apparently, surface modification of SiO2 by ICTOS is an effective way to improve the interaction energy between PI matrix and SiO 2 .…”

“…It can be explored, the real interaction and performance of two phases after modification, better by defining the characteristics of each component structure inside the materials. PI/SiO 2 nanocomposites have been extensively studied by specific experiments and relevant molecular dynamics (MD) simulation in recent years . Sushmit Goyal et al .…”

Study on the tribological properties of modified polyurethane material for water‐lubricated stern bearing

“…The thermal stability of the samples was tested by TGA, which was shown in Figure . With the thermal analyzer monitoring the weight of samples, the change curve was measured with the heating of the furnace . The analysis results showed that the weight of modified PU can retain more than 95% when the temperature increased at 200 °C, while can be maintained at 100% basically below 100 °C.…”