Morphology, Ionic-Molecular Interaction and Ionic Conductivity Behavior of PMMA/ENR 50 Electrolytes Containing Carboxylic Acids Modified SiO_2 Fillers

摘要

Carboxylic acids of various carbon chain lengths (C_n);;i.e. butanoic acid (C_4), octanoic acid (C_8), dodecanoic acid (C12) and hexadecanoic acid (C_(16)) have been used to organically modify silicon dioxide (SiO_2). The acid modification involve replacing the hydrogen atom of the silanol group (Si-OH) of SiO_2 with the R_nCOO- of the acid via esterification technique. SiCh and acid modified SiO_2 (MoC_n-SiO_2) were used as filler in preparation of polymethyl methacrylate/50% epoxidized natural rubber electrolytes containing SiO_2 (PEL-SiO_2) and MoC_n-SiO_2 (PEL-MoC_n-SiO_2) via solvent casting method with lithium tetrafluoroborate (LiBF4) as dopant salt. Field-emission scanning electron microscopy (FESEM) analysis of PEL-SiO_2 and PEL-MoC-SiO_2 films show LiBF4 accumulated to the fillers. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed formation of hydrogen bonding between LiBF4 with fillers and polymers in the polymer electrolyte films. Interestingly, the ionic conductivity of PEL-MoC_n-SiO_2 films increases as the C_n of acids increased with the highest ionic conductivity of 5.56 × 10~(-7) Scm~(-1) was achieved in PEL-MoC_(12)-SiO_2 film.