Dissolution and spectroscopic properties of the polydiacetylene poly(10,12-docosadiyne-1,12-diol-bisethylurethane)

Abstract

The polydiacetylenes with alkyl-urethane pendent groups, { - (CH2)nOCONHX}, have been extensively studied. The nBCMU polymers (X = - CH2COO(CH2)mCH3 , m = 3) are highly soluble while the nEU (X = - (CH2)mCH3, n = 1) and nPU (X = - C6H5) are much less soluble. All these polymers exhibit thermo- and solvato-chromism due to disordering of the conjugated backbone. -ray polymerised poly(10,12-docosadiyne-1,12-diol-bisethylurethane), 9EU, is insoluble in chloroform and is dissolved in N,N-dimethylformamide only on heating to 140°C. Mechanically disordered polymer films are partially dissolved in chloroform at room temperature. Boiling chloroform dissolves some, but not all, of the remaining polymer. Films either exposed to chloroform or heated above 130°C recover an ordered phase and become less soluble. Optical and FTIR-Raman spectra are reported for the films and solutions of 9EU and similarly treated films of 9BCMU. The spectra are interpreted in terms of the order present in the polymer backbone. These comparative studies indicate that a number of factors contribute to the low solubility of 9EU.