Dissolution and thermochromism of polydiacetylenes with chiral pendent groups

The absorption spectra of soluble polydiacetylenes with chiral pendent groups, –(CH2)nOCONHC*H(CH3)Ph, are reported. When n≥4 dissolution in chloroform gives yellow solutions of disordered, worm-like chains. The polymers with n=3 give brown to red solutions in chloroform and, on heating, in tetrahydrofuran. The spectra show that both disordered and ordered chains are present. The polymer fraction dissolved in tetrahydrofuran depends on the dissolution temperature. On heating there is a gradual transition to a yellow solution that is metastable at room temperature, the ordered chains being recovered slowly. Absorption bands associated with ordered chains having different structures are observed.