Influence of crosslink density on thermal, mechanical and dielectric properties of cross-linked fluorinated poly(aryl ether)s

Abstract

The rapid development of high-speed communication networks (for example, 5G) has imposed more stringent requirements on the comprehensive performance of low dielectric constant (low-k) polymeric materials, as an important member of which, fluoropolymer has gained much attention. In this study, a series of cross-linkable fluorinated poly(aryl ether)s with different phenylethynyl content have been synthesized through nucleophilic substitution reaction, then their polymeric films have been prepared and thermally cross-linked via phenylethynyl groups. Thermal, mechanical and dielectric properties of the films are systematically compared. Due to the presence of F atoms and cross-linked structure in polymer chains, these polymeric films exhibit remarkable dielectric properties with the lowest dielectric constant < 2.4 and dissipation factor < 0.003 at frequency from 100 Hz to 1 MHz. Moreover, the dielectric performance shows impressive temperature independence before 200 °C. Excellent mechanical properties of the films have been corroborated by the DMA data of Young’s modulus > 1.50 GPa and modulus retention rate > 70%. It is noteworthy that polymeric films possess very low dielectric constant and dielectric loss at high frequency of 10 GHz, of which the lowest values can reach 2.47 and 0.0018, respectively. The polymeric films constructed in this study have shown great application prospects in the field of high-speed communication.