CAREER: Integration of Sophisticated Stimuli-Response Capabilities into Highly-Distensible Nanostructured Hydrogels

Colorado State University, Fort Collins CO

Investigators

Abstract

TECHNICAL SUMMARY: Responsive hydrogel technologies are currently being pursued in a range of applications, including tissue scaffolds, chemical release agents, biosensors, and artificial muscles. However, their efficacy has been severely restricted by an inability to introduce accurate and tunable response mechanisms in a controlled fashion. This is often attributable to the inherently ill-defined structure of most systems, with gelation based on spatially random cross-links within the material, or poorly formed solid phase domains distributed non-uniformly throughout the sample. The ultimate goal of the research activities proposed in this CAREER award is the successful generation of a new class of highly distensible, nanostructured hydrogels, capable of sophisticated and tunable responses to a range of external stimuli. The first generation of hydrogels are to be fabricated by exploiting the melt-state self-assembly of sphere forming block copolymer amphiphiles, as extremely versatile templates for more highly functioning materials. Our goal is to generate hydrogels with integrated functionality permitting one to continuously tune, through external stimuli (e.g., temperature, pH, light, etc.), the dimensions, geometry, and size distribution of both the solution and solid phases in these gels, all with exacting control. At the same time, we aim to incorporate internal triggers that can induce more drastic material responses to an external stimulus, such as rapid and discontinuous changes in volume, modulus, or domain permeability. Extension of these ideas to non-spherical morphologies is expected to provide access to materials in which anisotropic swelling control is possible. While the preliminary work proposed focuses on the synthesis of the basic hydrogels and evaluation of their inherent response characteristics, the predominance of the work will be focused on the integration of advanced response mechanisms through synthetic modifications to the constituent block copolymers at the molecular level. The proposed research will be instrumental in the advancement of knowledge concerning the design of next generation, "intelligent" or responsive materials, capable of multiple simultaneous stimulus-induced behaviors, including: dissolution, swelling anisotropy, continuous and discontinuous expansion (and contraction), bending (and unbending), reversible self-adhesion, shape recovery, and triggerable chemical release. NON-TECHNICAL SUMMARY: The research proposed in this CAREER award is directed at the successful generation of a new class of super-absorbent polymeric materials that possess the unique capability of changing their most basic characteristics, such as shape, size, toughness, and permeability in direct response to an applied stimulus, such as UV light, heat, or an electric field, to name just a few. These materials are anticipated to have direct implications in advanced drug delivery, improved implant compatibility, degradable tissue scaffolds, artificial muscles, chemical and biological sensors, and biocatalysis. Thus, the proposed research is expected to have broad impact in a number of technologically important areas in which societal quality of life can be deeply affected. These research activities will be integrated with student education in a range of capacities, in an effort to bring the element of discovery in learning to promising young researchers. For example, the extensive inclusion of undergraduate students as active researchers on this project, integration of the results directly into course curricula, and the dissemination of results through undergraduate, graduate, and departmental seminars around the country and world permit this cutting edge research to become a mainstream learning tool. In addition, this CAREER award is also being used to develop annual one-day interactive research workshops for regional (Colorado and Wyoming) high school science teachers, in which recent topics in nanotechnology, biotechnology, and biomaterials can be discussed with world experts. The goal of these workshops is to provide each of the teachers with the hands-on materials to bring the latest research to life in their own classrooms, such that high school students will be able to share the excitement of the latest research at Colorado State University and around the world.