Porous structure and thermal stability of photosensitive silica/polyimide composites prepared by sol‐gel process

Abstract

The sol-gel method was employed to synthesize an inorganic-organic photosensitive composite material, silica/polyimide. Silica was covalently bonded to polyimide by introduction of 1,4-aminophenol as a coupling agent. A photosensitive cross-linking agent, 2-(dimethylamino) ethyl methacrylate, was used to engender UV sensitivity to the composite. Using field emission scanning electron microscope imaging at very high magnifications, the composite film was found to exhibit a porous crosssectional structure. The pores were interconnected to form numerous continuous channels within the matrix and silica particles were attached to the pore wall of the polyimide host. Depending on the preparation conditions, the size of the silica particles could vary from 20 nm to a few lm. The thermal degradation temperatures, dynamic mechanical properties, glass transition temperatures, thermal expansion coefficients, and dielectric constants of various silica/polyimide composites were measured, and the results indicated that incorporation of silica could improve the thermal and dimensional stabilities of the polyimide. Also, because the silica/polyimide composite had a porous interior structure, it had a rather low dielectric constant with the lowest achievable value being 1.82.

Effects of Silica Sol on Structure and Properties of Core-Shell Silicon-Acrylic Materials

“…The nano-silica particles in the continuous polymer atrix endowed the materials with better thermal stability through enhanced interfacial interactions, and the effect is more pronounced with increasing silica sol concentration. Similar phenomena are found by other researches [24]. However, the decomposition temperature decreased from 351.19˚C to 331.63˚C when silica sol concentration was greater than 6 wt%.…”

“…The increase of storage modulus can be attributed to the strong interfacial interaction between the organic polymer phase and the inorganic nano-silica phase. Similar phenomena were found in other researches [24]. However, the storage modulus decreased with further increase in silica sol concentration, which can be attributed to stress concentration and microphase separation induced by more crosslinking points in the system.…”

High-Performance Polymer Type Capacitors

“…Huang et al [60] employed the sol-gel method to synthesize an inorganic-organic photosensitive composite material, silica/polyimide. Silica was covalently bonded to polyimide by the introduction of 1,4-aminophenol as a coupling agent.…”

Preparation and applications of novel fluoroalkyl end‐capped oligomers/polyimide/silica nanocomposites

“…In a variety of traditional organic polymers, especially, aromatic polyimides are high‐performance polymeric materials characterized by exceptional thermal stability and mechanical and electrical properties which have been widely applied in the aerospace and electrical industries 3. Therefore, there has been great interest in the preparation of polyimides/silica nanocomposites due to not only the improvement of the mechanical properties, thermal stability, and adhesion property but also the decrease of the coefficient of thermal expansion of polyimides, because the parent silica nanoparticles possess the exceptionally high thermal stability and very low coefficient of thermal expansion 4–15. Usually, it is well known that fluorinated polymers can exhibit various interesting properties such as high thermal and oxidative stability, and excellent resistance to the most chemicals, which cannot be achieved by the corresponding non‐fluorinated polymers 16–19.…”