Simple determinations of the thickness and molecular orientations in some polymer monolayers by the Langmuir-Blodgett method

Abstract

The thickness of double layer spacings and possible molecular orientations of polyvinylbenzal, polyvinylbutyral and polymethylacrylate monolayers were estimated by comparing the interference color changes produced by the double layer spacings of polymers deposited on the top surface of 39 layers of barium stearate which were built up on a chromium finished metal plate, with a standard interference color of 39 layers consisting of a combination of barium stearate and arachidate multilayers. The single layer thickness of polyvinylbenzal was found to be 11 Å at all surface pressures of piston oils from low to high, while the thickness of the single layer spacing of the other two polymers varied with the increase in the surface pressure of piston oils. From these results, benzene rings in polyvinylbenzal monolayer were concluded to be vertically oriented under the applied surface pressures either on the water surface or on the metal plate. It was supposed that butyral groups in polyvinylbutyral monolayer tended gradually to orient vertically as the pressures of piston oils increased.

On the other hand, carboxymethyl groups in polymethylacrylate were considered to orient horizontally on the water surface or on the metal plate at low pressures, and to be submerged into water, while they were oriented vertically on the metal plate when the surface pressure increased.