On Thermal and Spectroscopic Studies of Poly(ethylene oxide)/Poly(methyl methacrylate) Blends with Lithium Perchlorate

Abstract

SummaryIn this study, thermal properties and ion‐polymer interactions of lithium perchlorate (LiClO4) in poly(ethylene oxide)/poly(methyl methacrylate) (PEO/PMMA) blend prepared by solution casting technique were elucidated. The spectroscopic studies of the salt‐free and salt‐doped PEO/PMMA blends were investigated using x‐ray diffraction (XRD) and Fourier transform infra‐red (FTIR), respectively. XRD study reveals that the crystalline structure of PEO is slight change when PMMA is blended to PEO. The thermal behaviour of PEO, PMMA and their blends with and without LiClO4 was investigated by differential scanning calorimetry (DSC). The presence of a single and composition dependent glass transition temperature (Tg) reflects the miscibility of the salt‐free PEO/PMMA blends in the molten state. The Tgs of PEO, PMMA and the blends generally increase with ascending mass fraction of salt (WS). However, PEO/PMMA 50/50 blend with WS ≥ 0.091 shows phase separation between the two polymers. The melting temperature (Tm) and crystallinity (X*) of PEO are suppressed when blended with PMMA, thus, confirm the miscibility of the salt‐free PEO/PMMA blends in the molten state. Presence of LiClO4 to PEO, PMMA and their blends does not influences the X* of PEO. Investigation by FTIR does not show any specific interaction between PEO and PMMA for the salt‐free blends whereas for the salt‐doped blends, Li+ ions are observed to coordinate with the oxygen atom of both the PEO ether and the PMMA carboxyl groups. Impedance spectroscopy study demonstrates that the LiClO4–doped PEO/PMMA 75/25 blend has lower ion conductivity than that of the PEO + LiClO4 system but recorded enhanced conductivity as compared to PMMA + LiClO4 systems at WS = 0.091.