Ordering and Properties of Confined Main Chain Liquid Crystalline Polymers

Ordering and Properties of Confined Main Chain Liquid Crystalline Polymers

Zhenpeng Li¹, Eric Baer², Donald R. Paul¹, Christopher J. Ellison¹

¹McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712

²Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106

Abstract

Liquid crystalline polymers (LCPs) possess many attractive properties, including outstanding chemical resistance, good mechanical properties and extraordinary gas/liquid barrier properties. Such unique properties show promise for applications in barrier packaging materials. Previous studies have demonstrated that the structures and properties of crystalline polymers can be dramatically affected through nano-confinement. However, only several studies have been performed on the study of confined LCPs, few with confined main chain LCPs (MCLCPs). Therefore, it would be very interesting to understand the morphology and properties of confined MCLCPs. In this study, Vectra (a commercial grade MCLCP) thin films with 20nm - 2μm in thickness have been made by spin coating and its structure and ordering under nano-confinement was studied. It was found that the Tg of Vectra could be profoundly affected by the confinement and the interfacial interaction with the substrate. Additionally, Vectra polymer chains exhibited ‘in-plane’ orientation with their long axis aligned parallel to the substrate. Such ‘in-plane’ ordering could enhance the O₂ barrier properties of Vectra due to the increased tortuosity of the diffusion path way.