Order-disorder transitions in self-assembled polymers: A positron annihilation study

We report here the first results of order-disorder transition (ODT) in a self-assembled comb-like polymer-amphiphile supramolecular system as identified from the change in positron lifetime parameters. We have used poly(4-vinyl pyridine) hydrogen bonded with 3-pentadecyl phenol, which upon heating showed a stepwise reduction in o-Ps intensity at the ODT from lamellar self-assembled state to the disordered state. The ODT temperature was confirmed by differential scanning calorimetry and small angle X-ray scattering. The free volume “holes” in this polymer-amphiphile system are proposed to be near the chain ends of the polymer backbones. We suggest that positron lifetime spectroscopy can serve as a technique to identify ODTs in self-assembled lamellar structured supramolecular systems.