The goal of my research is to develop novel polymeric materials that solidify upon exposure to an environmentally-borne initiation stimulus. Specifically, I propose the investigation of novel, in situ polymerizable materials based upon the radical-mediated thiol-ene reaction mechanism. This reaction mechanism has been a focus of recent attention as a click reaction, particularly for polymerizations, owing to its desirable combination of characteristics, including high yield, reaction specificity, and modularity. As thiol-ene reactions are extraordinarily resistant to oxygen inhibition, oxygen will be employed as a ubiquitous, environmentally-borne reactant. This mechanism will enable the development of materials that improve upon existing technologies used in the human habitation of space. The described research project will focus both on the fundamental chemistry and evolution of the polymer networks, and on the utilization of the polymerization initiation approach to yield materials that address the requirements of specific applications. Redox reaction mechanisms that utilize atmospheric oxygen to generate radicals will be investigated for the in situ polymerization of thiol-ene-based materials and the physicochemical properties of the resultant polymer networks will be characterized. To demonstrate the versatility of this approach, its utilization in two space technology applications will be investigated. Initially, surgical adhesives will be developed for use as emergency hemostats and other medical procedures that may be necessary to perform during space travel. Subsequently, a self-healing material that is able to flow and polymerize immediately after being punctured, thus sealing a wall defect, will be designed as a unique and robust atmosphere-loss prevention mechanism; such a material could be sandwiched within the layers of space suits or the walls of a spacecraft.