TRANSPARENT AND ADHESIVE POLYMER ELECTROLYTE FOR SMART WINDOWS - SYNTHESIS, CHARACTERIZATION AND IONIC-CONDUCTIVITY MEASUREMENTS

Transparent, adhesive and viscoelastic polymer electrolytes were synthesized from poly(propylene glycol) (PPG) (molecular weight 2000), poly(methyl methacrylate) (PMMA) and LiCF3SO3 for smart-window application. The synthesis was carried out by the matrix polymerization method. Methyl methacrylate was polymerized in PPG doped with LiCF3SO3 using azobisisobutyronitrile as the initiator. Interestingly, the presence of LiCF3SO3 makes the two otherwise incompatible polymers compatible. Various combinations of the salt and PMMA were tried to make it applicable for smart windows. The PMMA incorporated (up to 8%) by this method appears to form a protective coating for the PPG-salt complex, making it hydrophobic, and also increases the adhesiveness of the polymer electrolyte. The ionic conductivities of these polyelectrolytes were measured as a function of temperature. The plot of conductivity versus temperature was found to fit to the Vogel-Tammann-Fulcher equation over the temperature range -20 to 110-degrees-C. The glass transition temperature was determined by differential scanning calorimetry. At high O:M ratio (ratio of ether oxygens to alkali-metal cation), PMMA does increase the T(g) of the system, as can be expected. However, at low O:M ratio, PMMA does not seem to have any influence on the T(g) of the system. The PMMA was isolated from the reaction mixture and characterized by H-1 nuclear magnetic resonance and gel permeation chromatography analysis.