Investigating the Molecular Mechanisms of Thermally Active Amorphous Shape Memory Polymers

Johns Hopkins University, Baltimore MD

Investigators

Abstract

Investigating the Molecular Mechanisms of Thermally Active Amorphous Shape Memory Polymers Thermally induced shape memory polymers are flexible smart materials that respond to a specific temperature event by generating a shape change. The molecular mechanism underpinning the behavior of amorphous shape memory polymers is the dramatic change in the mobility of the polymer chains induced by the glass transition. At high temperature, the chains are mobile and can rearrange, e.g., through rotation or diffusion of chain segments, to an equilibrium structure and stress state in response to a temperature change or applied load. The mobility vanishes as the polymer is cooled to below the glass transition temperature. This curtails structural and stress relaxation mechanisms allowing the material to store a temporary shape. Reheating to above the transition temperature restores the mobility allowing the material to relax and recover the permanent shape. The objectives of this proposal are: (1) to develop a fundamental understanding of the importance of the temperature-dependent structural and stress relaxation mechanisms on the performance of thermally induced shape memory polymers, and (2) to identify key thermomechanical parameters and quantify their effects on the shape memory performance. The fundamental understanding, and the modeling and computational tools, which will be developed, by this research has the potential to impact a broad range of technologies by reducing the design and manufacturing costs and enabling new and integrated functionalities. These technologies include multifunctional shape memory polymer medical devices, integrated sensors and actuators, and deployable aerospace structures. This project will benefit engineering education by integrating the research activities into fundamental engineering classes on mechanics of materials, and numerical methods. In addition, women and minorities will be recruited for the research activities to promote the participation of underrepresentative groups in the area of smart materials mechanics.