STRUCTURAL RELAXATION OF LANGMUIR-BLODGETT-FILMS OF POLY(VINYL OCTANAL ACETAL) WITH VARIOUS TACTICITIES

Poly(vinyl octanal acetal) (PVO) was prepared from poly(vinyl alcohol) (PVA) in which the main chain had three different tacticities and the stereoregularity was characterized by H-1 NMR spectroscopy. a-PVO pre pared from atactic-PVA and s-PVO from syndiotactic-PVA had similar fra ctions of cis- and trans-acetals in the main chain, but i-PVO from iso tactic-PVA had different ones. Ultrathin films of these polymers were prepared by the Langmuir-Blodgett (LB) technique, and the thermal rela xation of their multilayer structure was investigated by the energy-tr ansfer method. When the LB films were composed of polymers which had a main chain with a similar stereostructure, the polymers were intermin gled with each other by the thermal treatment and the onset of the dif fusion of polymer segments was affected by the glass-transition temper ature of the bulk. In contrast, the polymers with different stereostru ctures in each layer were not mixed with each other, but phase-separat ed, presumably forming droplets in the ultrathin films. It is conclude d that the relaxation behavior of polymer LB films strongly reflects t he stereoregularity of the sample polymers.