FTIR spectra of plasticized grafted natural rubber-LiCF3SO3 electrolytes

Chemical modification of natural rubber (NR) has frequently been attempted to improve the performance in specific application. 30% poly(methyl metacrylate) (PMMA) grafted into NR (MG30) has been explored as a potential candidate for polymer electrolytes. The complexation effect of salt and plasticizer in polymer host electrolytes had been investigated using FTIR. The carbonyl stretch of MG30 locates at 1729 cm(-1), with the addition of lithium trimethanesulfonate (LiCF3SO3) salt, new band evolves at lower frequency region at 1643-1645 cm(-1). The nondegenerate vibrational mode of v(s)(SO3) of salted electrolytes appearing at 1031-1034 cm(-1) comes from 'free' trimethanesulfonate anions and the 1040-1046 cm(-1) absorption from the monodentate ion paired with triflates. These indicate MG30-salt interaction. When MG30 and ethylene carbonate (EC) formed film, the CH3 asymmetric bend of MG30 appearing at 1447 cm(-1) is shifted to 1449 cm(-1) in the EC-polymer complex. The C=O stretching at 1729 cm(-1) also shifted to 1728 cm(-1). Hence, the EC-MG30 system is complexed to each other. EC-LiCF3SO3 interactions are indicated by the shifting of C=O bending band of EC from 718 cm(-1) being shifted to 720 cm(-1) in the complex. In Li+-EC interaction where the ring breathing region at 897 cm(-1) in EC has shifted to 899 cm(-1) in EC-salt spectrum. The band appearing at 1643-1645 cm(-1) due to the coordination of Li+ <- O-C is still under observation and new peaks at 1779 and 1809 cm(-1) are responsible to the carbonyl stretches of EC in plasticized salt-polymer electrolytes. (c) 2005 Elsevier B.V. All rights reserved.