Structural Studies of Polymers with Hydrophilic Spacer Groups. 2. Infrared Spectroscopy of Langmuir-Blodgett Multilayers of Polymers with Fluorocarbon Side Chains at Ambient and Elevated Temperatures

Abstract

Multilayered Langmuir-Blodgett films of preformed polymers containing fluorocarbon side chains and hydrophilic spacer groups in the main chain have been investigated by IR spectroscopy. Grazing incident reflection and transmission measurements have been utilized to obtain information on the orientation of the side chains at room temperature and at elevated temperatures. Results indicate that the side chain is tilted relative to the surface normal unlike their hydrocarbon analogues, which are perpendicular to the surface. Although this angle of tilt increases at higher temperatures, it is shown that the initial orientation of the side chains returns when the film is cooled to ambient. This is found to be true even for temperatures as high as 150 °C in the homopolymer and 180 °C in the m = 5 copolymer, indicating that the main-chain spacer plays a major role in the high-temperature stability of these materials. The contribution of the rigid fluorocarbon side chain in this inherent thermal stability is discussed. © 1989, American Chemical Society. All rights reserved.