|Title||Synthesis, structure, and ionic conductivity of self-assembled amphiphilic poly(methacrylate) comb polymers|
|Publication Type||Journal Article|
|Year of Publication||2006|
|Authors||Gao Liu, Melanie T Reinhout, Brian Mainguy, Gregory L Baker|
|Keywords||copolymer electrolytes, crystallinity, crystallization, electrolyte membranes, ethers, film lithium batteries, gas separation, polymerization, side-chains, solid-state|
Methacrylate comb polymers were synthesized that have amphiphilic teeth of ethylene glycol oligomers capped with alkyl groups. Both segments are of exact length to promote self-organization and crystallization. The atactic methacrylate backbone plus close proximity to the polymer backbone inhibits crystallization of the oligoethyelene oxide segments, but the terminal alkyl segments readily crystallize. Wide-angle X-ray diffraction and differential scanning calorimetry were used to characterize polymer side chain crystallization and its evolution as a function of the length of the amphiphilic teeth. An analysis of the d spacings places the oligoethylene glycol segment and the first eight carbon atoms of the alkyl chain in an amorphous phase. An similar to 1 angstrom/carbon atom increase in the d spacing is consistent with the crystalline segments being tilted relative to the polymer backbone. When the number of carbon atoms in alkyl segments is >= 14, addition of LiClO4 yields an ionic conducting ethylene oxide phase with retention of the alkyl crystallization. These novel polymer electrolytes use crystallization as a structural element to maintain dimensional stability.