# Structure–Property Relationships in Cyanate Ester Composites Incorporating BaTiO3 and Transparent Glass Fillers

## TL;DR

This study explores how adding BaTiO3 and transparent glass fillers to cyanate ester composites can improve their dielectric properties for high-frequency electronics.

## Contribution

The novel use of transparent glass and BaTiO3 fillers with interfacial engineering to precisely tune dielectric properties in cyanate ester composites.

## Key findings

- TESPI surface modification improves interfacial bonding and filler dispersion in the composite matrix.
- A 15 wt% filler loading achieves optimal dielectric performance with a low loss of tan δ ≈ 0.0047.
- Excessive filler loading causes agglomeration and increased dielectric loss.

## Abstract

Polymer–ceramic composites based on cyanate ester resins have attracted increasing attention for high-frequency electronic applications due to their low dielectric loss, thermal stability, and dimensional reliability; however, achieving a targeted dielectric constant while maintaining low loss remains a key challenge. In this study, transparent glass powders and BaTiO3 ceramic fillers were incorporated into a cyanate ester matrix to systematically investigate structure–property relationships and optimize dielectric performance for antenna-related applications. Transparent glass powders were synthesized via a melt-quenching route and combined with submicron BaTiO3 particles, while both fillers were surface-modified using 3-triethoxysilylpropyl isocyanate (TESPI) to enhance interfacial compatibility. Composite samples containing 5–30 wt% total filler were fabricated and characterized by XRD, FTIR, tensile testing, dielectric measurements, and SEM/EDX analyses. The results demonstrate that TESPI surface modification promotes strong interfacial bonding and homogeneous filler dispersion within the cyanate ester matrix. An optimal balance between mechanical integrity and dielectric performance was achieved at 15 wt% total filler loading (K3), exhibiting a dielectric constant close to 10 and the lowest dielectric loss (tan δ ≈ 0.0047 at 1 MHz). Microstructural observations confirm that excessive filler loading leads to agglomeration and increased dielectric loss. Overall, the combined use of transparent glass and BaTiO3 fillers, together with effective interfacial engineering, enables precise tuning of dielectric properties in cyanate ester composites for high-frequency electronic applications.