(722ab) Probing Mechanical Function of Vertical Multi-Layered Systems by Enhancing the Adhesion at the Interface

Forced-assembly is a process by which immiscible polymers are co-extruded through a series of die elements termed as ?multipliers' to form multi-layered films. This layering process, which offers advantages of continuous film formation and selective tuning of interphase thickness and layer spacing, provides a unique method to probe the nature of the interphase and to determine its relationship to mechanical function of the polymeric system. Recent advances in microlayering have focused on the development of vertical multi-layers. It is anticipated that the interphase between layers A and B is inherently weak along the length of film when subjected to applied tension along the transverse direction of the film. Through the use of dynamic mechanical analysis and tensile testing, it has been shown that these materials are mechanically anisotropic by nature, and thus, are interesting systems for probing mechanical function. The modulus of these films drops significantly when the force is applied perpendicular to the direction of flow in the system. This can be attributed to the weak adhesion properties of the interphase in vertical multi-layered films. Probing chemical interactions between the polymers in the vertical layered systems would lead to control of interfacial adhesive properties, hence increasing the mechanical properties of the system.

Multi-layer co-extrusion will be utilized to produce novel materials with enhanced mechanical properties through selective manipulation of the interphase. It is expected that control of interfacial adhesion through ultraviolet (UV) crosslinking or ionic interactions, enhanced mechanical properties can be achieved, particularly along the length of the film.

"This material is based upon work supported by the National Science

Foundation under Grant No. DMR 0423914."