Synthesis and characterization of PEDOT: P(SS-co-VTMS) with hydrophobic properties and excellent thermal stability

Hydrophobic and comparatively thermally-stable poly(3,4-ethylenedioxythiophene), i.e., poly(styrene sulfonate-co-vinyltrimethoxysilane) (PEDOT: P(SS-co-VTMS)) copolymer was successfully synthesized via the introduction of silane coupling agent into the PSS main chain to form P(SS-co-VTMS) copolymers. PSS and P(SS-co-VMTS) copolymers were successfully synthesized via radical solution polymerization, and PEDOT: P(SS-co-VTMS) was synthesized via Fe⁺-catalyzed oxidative polymerization. The characterization of PEDOT:P(SS-co-VTMS) was performed through an analysis of Fourier transform infrared spectroscopy (FTIR) results, water contact angle and optical images. The electrical properties of conductive PEDOT:P(SS-co-VTMS) thin films were evaluated by studying the influence of the VTMS content on the electrical and physical properties. The conductivity of PEDOT:P(SS-co-VTMS) decreased with an increase in the VTMS content, but was close to that of the PEDOT:PSS, 235.9 S. cm^-1. The introduction of VTMS into the PSS copolymer improved the mechanical properties and thermal stability and increased the hydrophobicity. The thermal stability test at a temperature over 240 °C indicated that the sheet resistance of PEDOT:PSS increased by 3,012%. The sheet resistance of PEDOT:P(SS-co-VTMS), on the other hand, only increased by 480%. The stability of PEDOT:P(SS-co-VTMS) was six-times higher than that of the reference PEDOT:PSS.