SYNTHESIS AND PROPERTIES OF DIACETYLENIC GLUTAMATE LIPID MONOMER AND POLYMER - THERMOCHROMIC POLYDIACETYLENE FREESTANDING FILMS

A novel double-chain diacetylene lipid based on a glutamate backbone, bis(docosa-10,12-diynyl) N-[6-(triethylammonio)hexanoyl]-L-glutamate bromide, was prepared by a multistep synthesis. Vesicles were formed by room-temperature sonication of the hydrated lipid. At 0 °C, the vesicles were readily polymerized by UV irradiation and the polydiacetylene (PDA) vesicles showed a two-stage thermochromic phase transition as the temperature was elevated. In the first irreversible stage, the PDA vesicles turned from blue to orange-red on warming to room temperature; in the second reversible stage, they turned from orange-red to yellow-orange on warming to 50 °C. Ordered multilayer films of the diacetylene lipid were cast from unpolymerized bilayer vesicles. Photopolymerization of these cast multilayer films yield highly colored polydiacetylenic films, thereby demonstrating that the molecular order inherent in the bilayer vesicles is retained during the casting procedure. The cast, polymerized films of PDA could be stripped from the support to give free-standing thin films of PDA, which were not disrupted by treatment with organic solvents. The PDA films showed reversible thermochromic phase transitions. Treatment of the PDA films with iodine vapors increased the electrical conductivity to 6 × 10-4 Ω-1 cm-1. © 1990, American Chemical Society. All rights reserved.