Single component polymeric materials processed into simple structures will find difficulty in satisfying the increasing complex demand for multifunction and smart use required today. Innovative layered materials will potentially be great alternatives to simple systems due to their flexibility in design and architecture. The layered materials can combine the properties of each individual layer as well as the synergistic effects between layers to enhance those properties if properly manipulated. Layered materials can be prepared via the artful application of layer multiplying coextrusion, freeze-drying and composite laminating methods as described in this research, combining materials processing different chemical structures, polymeric components and material types.
The thermoplastic polyurethanes introduced in this work are block copolymers of alternating hard and soft segments. These molecular-level layered materials will exhibit various thermal, mechanical and oxygen transport properties as a result of varying the hard and soft segment species, molecular weights, ratios and chain extenders. A correlation between oxygen gas permeability and thermal transitions will be presented.
Pellet size and shaped multilayer films can be designed and prepared via layer multiplying coextrusion. These nano/micro-level layered materials when injection-molded with polymer matrix, will release individual layers as reinforcing fillers, simulating clay platelet behaviors in polymer melts. Polymer composites with additives provided in this manner exhibit better mechanical properties than those produced using conventional melt blending methods.
Polymer/clay aerogels prepared via an environmentally friendly freeze-drying technique, are ultra-low density, porous, foam-like materials with micro-level layered structures. The morphologies of polymer/clay aerogels are greatly influenced by the freezing temperatures employed; mechanical properties follow structure. Biopolymer/ clay aerogels are being developed as competitive packaging materials to expanded polystyrene foam. Polymer/clay aerogels can also be converted into films via compression-molding; high clay loadings with good gas barrier properties can be achieved. These ultra-low density materials can serve as the matrix for glass fabric laminates with macro-level layered structure, both with and without epoxy adhesives, exhibiting good mechanical properties. Various polymer/clay aerogel systems are discussed as illustrating examples.