Role of interface in highly filled epoxy/BaTiO₃nanocomposites. Part II- effect of nanoparticle surface chemistry on processing, thermal expansion, energy storage and breakdown strength of the nanocomposites

Abstract

Highly filled dielectric polymer nanocomposites with high dielectric constant nanoparticles (e.g., BaTiO 3 ) have promising application in many fields such as energy storage. The effectiveness of these nanoparticles to increase the dielectric constant and energy density of the resulting nanocomposites has already been demonstrated. However, the role of interface between the nanoparticles and polymer matrix on thermal expansion, energy storage and breakdown strength-the three parameters that are important for practical application of the dielectric polymer nanocomposites, has not been systematically documented. In this contribution, we investigated the effect of six kinds of nanoparticle surface chemistry on the processing, coefficient of thermal expansion, energy storage and breakdown strength of highly filled epoxy/BaTiO 3 nanocomposites. It was found that all these aspects, in particular the processability of the nanocomposites, are associated with the nanoparticle surface chemistry. Combining the processability, coefficient of thermal expansion, energy storage and breakdown strength of the nanocomposites, we conclude that the nanoparticles functionalized by silane coupling agents with terminal groups capable of reacting with the epoxy matrix are more suitable for preparing highly filled dielectric polymer nanocomposites.

Enhancement of dielectric constants of epoxy thermosets via a fine dispersion of barium titanate nanoparticles

“…Of the various approaches used for surface modification, organosilane coupling agents bearing the functional groups reactive with epoxy (e.g., epoxide and amino groups) were often used. We found that the formation of the chemical linkages between the epoxy and BT NPs were critical in the suppression of the aggregation of the inorganic components in the organic matrix . For instance, Iijima et al .…”

“…Organic–inorganic epoxy nanocomposites with high dielectric constants have attracted considerable interest in the microelectronics industry because of their easy processing, compatibility with printed wiring boards, and low cost . It has been realized that the dielectric constant of epoxies can be increased through the incorporation of conductive fillers (e.g., carbon nanotubes, metals, conductive polymers or high‐electric‐constant ceramic fillers, such as ZrO 2 , TiO 2 , and BaTiO 3 . Epoxy composites filled with conductive fillers can exhibit high dielectric constants; however, this class of composites can suffer from a very high dielectric loss because of the high electrical conductivity of the fillers.…”

“…This greatly limits applications of the composite materials in the electric industry. In marked contrast to composites containing conductive fillers, composites containing nanosized ceramics with high dielectric constants can display quite high dielectric constants but relatively low dielectric losses . Barium titanate (BT) is a traditional ferroelectric ceramic, and it has excellent dielectric properties: a high dielectric constant and a low dielectric loss.…”

“…For a successful application, measures must be taken to suppress the macroscopic aggregation of the inorganic fillers in organic polymers. In past years, there have been some reports on the preparation of organic–inorganic nanocomposites of epoxy thermosets with BT NPs in epoxy thermosets . Alam et al .…”

“…modified the surface of BT NPs with 3‐glycidoxypropyl trimethoxysilane and achieved a fine dispersion of BT NPs in the epoxy matrix via the interfacial reaction of BT NPs with the epoxy matrix. Huang et al . reported the surface modification of BT NPs with organosilane coupling agents bearing some reactive groups, such as epoxide, thiol, and amino groups.…”