Solvent Resistant Elastomers and High TG Materials from the Same Carbosilane Backbone: Broadening the Materials Response

摘要

An important Army research mission is to investigate chemistry leading to better solvent resistant elastomers for military uses as found in face masks, hoses, belts, mounting structures for vehicles, and the like. Our strategy to meet the challenges of this mission begins with creating a base polymer formulation, whereby simple changes in monomer ratio lead to either soft, elastic polymers or hard, tough materials. We have directed our efforts towards solvent resistant materials that improve upon butyl rubber. Polycarobcsilanes combine the behavioral characteristics of hydrocarbon polymers and siloxane elastomers. We have identified two key structural features in polycarbosilanes that lead to both greater elasticity and higher tear strength. Greater elasticity can be achieved by increasing the run length from just one repeat unit to three repeat units within the soft monomer-the effect is dramatic. Higher tear strength is attained by introducing chain-end latent crosslinking to complement the chain-internal crosslinking-the latter concept, chain-internal latent crosslinking was defined in earlier work. Chain-end latent crosslinking has enhanced the solvent resistance of these polycarbosilane elastomers. Interactions with the Army Research Laboratory in Aberdeen, along with Dr. Doug Kiserow of the ARO, have been most helpful.