Phase Behavior of Polystyrene-<i>block</i>-poly(4-vinylpyridine) Copolymers Coordinated by Metal Chloride

Abstract

The effect of cadmium chloride (CdCl 2 ) on the phase behavior of polystyrene- block -poly(4-vinylpyridine) copolymer (S4VP) was investigated by using rheometry, small-angle X-ray scattering, and transmission electron microscopy. For this purpose, symmetric S4VPs with various molecular weights were prepared by anionic polymerization. We found that with the addition of CdCl 2 the order-to-disorder transition of S4VP was significantly increased because of the intermolecular coordination connecting different P4VP block chains. We also studied the change of the domain spacing ( D ) upon addition of CdCl 2 as well as gelation behavior. At a relatively low content of CdCl 2 (γ < 6, where γ is the number of coordinated CdCl 2 per chain), D remains unchanged. However, when the amount of CdCl 2 increases further, D begins to decrease due to many coordinations of CdCl 2 that strongly perturb block copolymer conformation, including many ring closures. Furthermore, it is found that the scaled gelation point increases with increasing molecular weights of S4VP.