Chemical Surface Texturing through Block Copolymer Morphology

• Simone Meyers, Material Science, University of Delaware

• Charles Dhong, Biomedical Engineering, University of Delaware

The human sense of fine touch uses mechanical stimuli such as friction and adhesion to process information about the textures of various objects. Current haptic devices, including tactile aids, typically only employ physical features such as bumps or grooves to recreate tactile sensations. However, no more than 5 physical textures can be applied onto a surface simultaneously. Consequently, this defined upper limit of “tactile clutter” minimizes the ability to generate and recreate touch compared to other senses. Here, we investigate textures generated by chemical features, specifically block copolymer film morphology, for richer tactile feedback. Previous work on polystyrene films has shown that polymer crystallinity and tacticity alone can elicit distinct sensations. We hypothesize block copolymers composed of 2 distinct chemical structures can provide more control to create certain surface textures through changes in their morphology. We synthesized blocked polystyrene (PS) and polyethylene oxide (PEO) thin films that varied in their block lengths and film thickness as well as drying, annealing, and sonication steps to create specific chemical morphologies. We observed that with longer drying periods, the films displayed more cracks on the surface but less clusters of individual polymer. In addition, it was determined that hot plate annealing allowed for more controlled conditions while heating the film. Optimized films will then be evaluated through mechanical and human testing to identify frictional signatures and determine how distinct they feel. We anticipate that this work should provide a framework to design a larger material library for modern tactile interfaces.