Developing smart materials that respond to external stimuli is a central goal of materials science. Adhesion is a material property that is important in many areas of industry and medicine. Light is a stimulus that is easy to tune and convenient to use in both biological tissues and industry.<br/>Scientist in many fields have demonstrated light induced adhesion based on cross-linking for various applications, however reversible adhesives have not been fully developed. Our strategy was to use photochromic molecules dissolved in a polymer to change chemical interactions and consequently modulate adhesion. Photochromic molecules are molecules that undergo structural change upon light irradiation.<br/>In our previous studies we demonstrated that we could significantly increase adhesion of a polystyrene polymer film to a glass surface using nitro spiropyran as the photochromic molecule. We have recently developed a way to switch adhesion off using light and a different photochrome. As a final goal we want to increase and decrease adhesion based on our needs in one sample. In the current studies we have tried to use both molecules with on optimized concentration. We found out that shining UV light will increase adhesion of thin films of polystyrene (PS) to the substrate and irradiating laser light will decrease adhesion. This will help us to engineer a controlled release devise which enable us to release encapsulated chemicals from wells or capsules whenever needed. As a proof-of-principle, we encapsulated a food dye in a small well of microscopic slide and covered it with small cover glass and glued them together using a polystyrene/photochrome mixture. Upon UV irradiation the adhesion of our glue increased and after visible irradiation the glass cover detached, and the encapsulated dye released. We are working on different substrate and polymers to maximizing the control of adhesion by light.

Photoinduced changes in polymer-glass adhesion

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.