Influence of curing agent on dielectric properties of crosslinked poly(vinylalcohol-co-vinylcyanoethoxy)

Abstract

Organic electronic devices require dielectric layers made from materials with high dielectric constant (e′) and good dielectric strength, which allow reducing the threshold voltage and decreasing the power consumption of electronic circuitry. Poly(vinylalcohol-co-vinylcyanoethoxy) (CEPVA) has high e′ (≈ 15) and low conductivity (σ′), which are exactly the characteristics needed for dielectrics. Its Tg close to room temperature limits, however, its applicability in electronics and improvements of its stability and mechanical properties are necessary. Here, we report on curing of this polymer, exploiting the residual hydroxyl groups present in the polymers after reaction of the parent poly(vinylalcohol) with acrylonitrile. Different curing agents were tested and showed a strong influence on the relaxation phenomena of the crosslinked polymer. The reduced mobility of backbone and side groups of the polymer decreased e′ but improved the mechanical stability at high temperature and decreased σ′, especially at low frequencies, where ionic conductivity and interface polarization usually occur. At the same time, the hydrophilicity of the polymer was reduced.