(647e) Visualizing Penetration of Fluorescent Dye Through Polymer Coatings

Polymer coatings are critical as protective barriers and it would be beneficial to understand how the polymer properties relate to the penetration of small molecules and their subsequent contamination of coatings. Towards this goal, we investigate how a model dye molecule contaminates block copolymer coatings. In a typical experiment, a drop of fluorescent Rhodamine B dye solution of known concentration is placed on a coating of micron-order thickness, while confocal microscopy is used to visualize the resultant fluorescence inside the coating over time. As a starting point, block copolymers are synthesized with polystyrene (PS) blocks and modifiable polydimethylsiloxane (PDMS) blocks. Using image analysis methods, we track the temporal and spatial fluorescence distribution in the coating. A semi-empirical model is developed to determine the rate of contamination; we demonstrate that dye penetration is related to the chemical makeup and configuration of the block copolymers. Our work shows that confocal microscopy can be a useful tool to visualize the transport of a fluorophore in space and time through a coating. Ultimately, we expect that a better understanding of how small molecules penetrate into polymers will help guide the design of more effective coatings for a wide range of applications.