Polymer composites are attractive materials owing to their increased toughness and reduced costs. Replacement of metals in certain applications can reduce costs as well as carbon dioxide emissions through reduction of required concrete volume and automotive light weighting. However, a greater understanding of polymer composite failure mechanisms from the molecular to bulk scale is needed. Stimuli responsive fluorescent sensors are a window into local processes ranging from water uptake, polymer dynamics, and damage. This project puts an emphasis on design, synthesis, and application of these sensors to polymeric systems in order to visualize and quantify these phenomena from the molecular to larger length scales.