Polyimide-Silica Nanohybrids—Their Characterization and Properties

Polyimide-Silica Nanohybrids—Their Characterization and Properties 

Pis have munerous applications in the electronics industries and improvements in their properties are vital in regard to increasing such applications. 

Recently, incorporating silica components, in the form of nanohybrid composites, into the PI matrix has enhanced their thermal properties and reduced their coefficients of thermal expansion compared to the pure Pis. The combination of nanoscale inorganic components and Pis has great potential for imcovering future applications and, therefore, it has attracted a lot of attention during the last few years. This section focuses on the most well understood principal concepts used to incorporate inorganic components, such as silica or sihca-like materials, into polyimides and the resulting properties of such nanohybrids. 

Kim and coworkers ° studied the effects of TEOS content on the dielectric constant of Pl-silica hybrid composites. They foimd that the values of the dielectric constant of the hybrid composite films increased monotonically upon increasing the amount of TEOS because of the inherent higher dielectric constant of silica relative to that of pure polyimide. The Pl-sihca hybrid fUms prepared from PAA possess higher dielectric constant than those of the Pl-sihca composite films in polyamic acid diethyl ester. This difference was ascribed to the uniformity of the distributed nanometer-scale particles in the former set of hybrid composite films. 

The silica domains incorporated into the polyimide matrix exhibit improved thermal stabiUty relative to that of pine polyimide because of the inherent thermal stability of the inorganic component, silica. The compatibilized hybrid (such as the 3APSSQ-containing Pl-sihca) possesses much greater thermal stability because of the presence of chemical bonds, provided by the coupling agent between PI and silica. Sometimes, because of possible reactions between them at the temperatures used, the cyclization of the polyamic acid to form PI may not reach completion and this effect could reduce the thermal stability of polyimide.  

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B. Polyimide-Silica Nanohybrids—Their Characterization and Properties... 

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