Coextrusion of Liquid Crystalline Polymer Multilayer Films for Gas Barrier Applications

Eric Baer, Case Western Reserve University, DMR 423914

Researchers at the NSF Science and Technology Center for Layered Polymeric Systems (CLiPS) have developed for the first time High Quality Liquid Crystalline Polymer (LCP) Multilayer Films by coextruding rheologically modified LCP materials. This modification enabled LCP films to be produced with layers as thin as several hundred nanometers.  The fabrication of LCP multilayer films has long been sought for many gas barrier applications. For example, they meet application requirements for preserving packaged foods and encapsulating organic electronic devices, such as light emitting diodes, that are sensitive to oxygen during operation. In addition, the incorporation of LCP as a very thin layer lowers the cost of LCP-based membrane products making them even more attractive to industry. Coextrusion is an ideal process to incorporate LCPs into multilayer film products with high throughput. Until now this has never been successfully demonstrated due to the poor flow properties of the LCP. CLiPS researchers have developed new methods to modify the flow properties of the LCP to make it suitable for manufacturing multilayer films. More importantly, the multilayer films can now be made with very thin, active LCP layers that compensate for their expense compared to conventional polymers, therefore reducing the price of the membrane products. This accomplishment has attracted the attention worldwide.

Figure 1. Cross-sectional SEM images of (a) neat V400p LCP/PP-g-MA multilayer film showing layer breakup when the LCP is not rheologically modified and (b, c) different magnifications of a Heloxy 67 modified V400p LCP/PP-g-MA high quality multilayer film.

Figure 2. Consecutive cross-sectional SEM images showing the layer integrity of the rheologically modified V400p LCP/PP-g-MA multilayer films over large distances.

CLiPS Envoy Alumni Bring Education Full CircleEric Baer, Case Western Reserve University, DMR 423914

The CLiPS Envoys Program operates year around. Summer is a particularly busy time, however, as the new Envoys are oriented to the program and extensive teaching is accomplished for Envoys at all levels. The summer Envoy curriculum includes ethics training, laboratory safety training; it includes information on preparing a research poster and practice sessions on giving a research presentation. Didactic instruction has been added since the beginning of the program in response to the graduate student mentors’ assessment of topics on which the Envoys need to improve in order to have a rewarding experience in the lab. Instruction includes mathematics, from algebra to pre-calculus, that is geared to the level of the learner and introduction to college chemistry. Even though polymers are CLiPS’s bread and butter, the characteristics and applications of polymers are not well known among our high school students, therefore an introduction to polymer science is one of the topics covered during the summer session. During the summer of 2014 we added several sessions on dimensional analysis, and an introduction to college physics.  Envoy Alumni have become an important component to the program. This year two of the Envoy alumni who are undergraduate students at CWRU participated as the math instructors. Our Envoy alumna, who is a PhD candidate in Macromolecular Science and Engineering, continues as a mentor in the program.