CAREER: Creasing of Surface-Attached Polymer Gels

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

TECHNICAL SUMMARY This goal of this research program is to develop a detailed understanding of the creasing instability induced by swelling of surface-attached polymer gels. Though this phenomenon has been observed in a variety of contexts since at least the mid-1800's, it remains poorly characterized and not widely appreciated. However, it has important implications for modern materials research in areas such as biomaterials and "smart" surfaces, and offers unique opportunities for the design of surfaces with switchable properties. The PI's work will focus on model hydrogel systems that allow quantitative determination of the following: (i) the conditions under which creasing occurs and how the onset of the instability depends on the material properties of the soft surface; (ii) the structures naturally adopted by creases, and how these structures can be controlled by proper material design; and (iii) how surface properties are altered by crease formation. Using the fundamental understanding gained through these experiments, responsive surfaces that dynamically alter their topography and chemistry in response to environmental cues will be designed. This research will be integrated into a variety of educational experiences in the laboratory and the classroom for students at the graduate, undergraduate, and K-12 levels. NON-TECHNICAL SUMMARY Coating a material with a thin layer of polymers provides a powerful way to control its surface properties. For example, surface-attached hydrogels (soft polymeric solids consisting primarily of water) are used to tune the interactions of materials with biological cells, and to create "smart" materials that sense and respond to changes in their environment. Under certain conditions, these soft polymer layers can undergo an instability in which their free surfaces spontaneously buckle and fold to form topographical features. This project aims to develop a thorough understanding of this instability, and its importance for surface properties, with significant impacts expected on the way that materials at the biological interface are designed, and on the creation of surfaces that can alter their properties on demand. In addition to providing technical training for undergraduate and graduate students in interdisciplinary areas of materials research, this program will offer the next generation of science educators at UMass an opportunity for a solid introduction to effective teaching strategies. Through a partnership with the Boston Museum of Science, the scientific results from this program will be incorporated into modules that reach a broader audience beyond the university.