Modeling Actuation and Shape Selection in Soft Materials

Kent State University, Kent OH

Investigators

Abstract

This award supports theoretical research, both analytical and computational, on a range of problems that span fundamental physics to industrial applications. The research focus is on soft materials as might be found in rubbers or naturally in biological systems, e.g., muscles. The research will look at how certain types of rubber-like materials respond to external stimuli such as electric currents. Another topic of research is how biomolecules and simple biological structures assemble to form more complex structures. The research will involve students and postdoctoral research associates. The principal investigators will carry out theoretical analysis and computer simulation studies of two problems related to shape evolution in soft materials. First, they focus on the actuation of liquid crystal elastomers, which change their shape in response to changes in temperature, applied electric fields, and optical illumination. These materials can bend as well as lengthen and contract, and have the potential to be used as "artificial muscles" for robotics, MEMS, and microfluidics applications. Second, the principal investigators will investigate self-assembled microstructures of amphiphilic molecules, such as lipid tubules and helical ribbons, which spontaneously form in complex shapes out of solution. These structures have applications in microencapsulation and controlled release, and can also serve as templates to form metallic microstructures used in microwave-absorbing composite materials. This type of self-assembly is also observed in biological materials, such as bile, both in vivo and in vitro. In both liquid crystal elastomers and in self-assembly of tubules and ribbons, materials of interest exhibit unusual combinations of ferroelasticity, ferroelectricity, and/or flexoelectricity. Mesogenic ordering of the material and chirality/chiral symmetry-breaking also play important roles. Each unique combination of material properties creates new opportunities for technology development and new challenges for both fundamental theory and materials engineering. Intellectual merit: The primary goals of the project are (1) to make progress with the development of fundamental theory of these materials, and (2) to apply that theory to create a continuum-scale finite element simulation tool to model the dynamics of these materials at the device level and on long time scales. This project is thus intended to bridge the gap from fundamental soft condensed matter theory to materials engineering and even product design. The new simulation tool represents a novel application of finite element elastodynamics to study shape changes caused by evolving mesogenic order in soft materials. The principal investigators have a strong record of fruitful collaboration and bring complementary expertise in analytical calculations and computer simulation to the work. Kent State University's Liquid Crystal Institute is a center of excellence in the study of soft materials and provides an ideal location for this research. Broader impacts: The project will involve the active participation of a graduate student and a postdoctoral fellow, with additional participation of students provided by the Chemical Physics Interdisciplinary Program at Kent State University. Both investigators have an exceptional track record in recruiting and working with female and minority students, and already have female and minority students working in their group at Kent State University. The investigators will participate in the Liquid Crystal Institute's ongoing community outreach activities, including presentations at local K-12 schools and hosting visiting student groups. The soft materials studied here are promising for a wide range of technological applications mentioned above. Through the Liquid Crystal Institute's well-established Industrial Partnership Program, we plan to transition the developed simulation tools and technological concepts for commercial use.