Spectroscopy and Kinetics of a Planar-Nonplanar Conformational Transition in Polydiacetylene Solutions

Poly3BCMU, a polydiacetylene with bulky urethane substituents, readily dissolves in common organic solvents such as CHCl3 to yield a yellow polymer solution. On addition of a nonsolvent, such as hexane, a dramatic color change takes place to yield a blue polymer solution. The variation in optical properties during this color transition is reviewed and discussed. New data on the kinetics of the transition are presented. The results strongly support a model which invokes a planar-nonplanar conformational transition involving the individual polydiacetylene chains in solution.