Effects of Dodecanoic Acid Modified SIO₂ on Filler Dispersion and Ionic Conductivity of PMMA/ENR 50/LIBF₄ Electrolytes

Abstract

Previously, the addition of silicon dioxide (SiO2) improved the homogeneity of polymethyl methacrylate/50 % epoxidised natural rubber (PMMA/ENR 50) blend. However, the presence of SiO2 agglomerates limits its overall performance. The formation of these agglomerates was due to the hydrogen bonding interaction that form between the oxygen atoms in silanol groups (Si-OH) and hydrogen atoms from the surrounding moisture. Therefore, in this study, SiO2 were modified with dodecanoic acid (DOA) to reduce the number of Si-OH on the SiO2 surface using esterification technique. Interestingly, it was found that the addition of DOA modified SiO2 (D-SiO2) improves the homogeneity of PMMA/ENR 50 blend. However, the amount of DOA used in the modification affect the capability of forming hydrogen bonding with the neighbouring of polymer chain. Different amounts of DOA were used upon the surface modification of SiO2 filler and then were added into PMMA/ENR 50 blends doped with lithium tetrafluoroborate (LiBF4). The films were prepared by solvent casting technique. CHNS analysis proven the increases of percentage of carbon atoms in D-SiO2. The attachment of DOA on SiO2 surface was confirmed using Fourier transform infrared spectroscopy (FTIR) and ionic conductivity of PMMA/ENR 50/LiBF4 filled D-SiO2 films was measured by electrochemical impedance spectroscopy (EIS). The result shows the blend properties and ionic conductivity of PMMA/ENR 50 filled D-SiO2 films was improved due to surface modification of SiO2 filler.

Morphology, Ionic-Molecular Interaction and Ionic Conductivity Behavior of PMMA/ENR 50 Electrolytes Containing Carboxylic Acids Modified SiO₂ Fillers

“…Generally, a better dispersion of LiBF4 was obtained in PEL-MoCn-SiO2 films compared to PEL-SiO2 film. This probably due the ability of acid modification to reduce the agglomeration of MoCn-SiO2 by reduced the number of possible sites for hydrogen bonding between filler [21]. Interestingly, PEL-MoC12-SiO2 film showed the smoothest morphology amongst the PEL-MoCn-SiO2 films maybe due to MoC12-SiO2 filler possesses compact structure and lesser Si-OH groups.…”