Akademik Veri Yönetim Sistemi
Colloids and Surfaces A: Physicochemical and Engineering Aspects, cilt.687, 2024 (SCI-Expanded)
This study investigates the ionic conductivity and dielectric properties of SPEEK-PEG-TMOS solid-state polymer electrolytes across a broad frequency spectrum (0.1–1000 kHz). Proton transport mechanisms were explored over an extensive temperature range, and positron annihilation lifetime spectroscopy (PALS) was employed to elucidate the roles of free volumes in the transport mechanism. At elevated temperatures, sulfonic acid groups and free volume defects predominantly govern the conductivity in all polymer electrolytes. PEG incorporation significantly improved proton conductivity at low temperatures, while the presence of TMOS and higher PEG content have elevated conductivity at higher temperatures. Proton conductivity mechanisms at elevated temperatures are influenced by SPEEK's intrinsic proton conductivity, PEG's plasticizing effect, acid-base interactions, and the presence of free volumes. PALS analysis reveals temperature-dependent trends in the o-Ps lifetime, intensity, and free volume fraction, increasing linearly with temperature due to thermal expansion. PEG content modulated this trend, with lower PEG content samples displaying lower thermal expansion slopes, and higher PEG content samples exhibiting more substantial increases in hole-free volume. The o-Ps intensity displayed a temperature-dependent change attributed to PEG's thermal expansion limitations. These insights contributed to a comprehensive understanding of the intricate interplay between PEG content, thermal expansion, and free volume in SPEEK-PEG-TMOS composites. The study has implications for material science applications, particularly in the development of high-temperature, anhydrous proton-conductive systems.