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Published online by Cambridge University Press: 16 February 2011
Subjecting crystals of the thermochromic polydiacetylene (PDA) from the bis (ethyl ure thane) of 5,7-dodecadiyne-1, 12-diol (ETCD) to the solvents chlorobenzene and ?,?-dimethylformamide above the thermochromic transition temperature of PDA-ETCD irreversibly converts the material to nonthermochromic forms. These new forms have been characterized by their structural, thermal, and spectral properties. The materials isolated after exposure to chlorobenzene are highly crystalline with a structure that has expanded and disordered, yet is still related to that of the pristine polymer. The observed properties are discussed in the framework of the crystal structure-thermochromism relationship for urethane-substituted PDA.