This GOALI award, co-funded by the Office of Multidisciplinary Activities of the Directorate for Mathematical and Physical Sciences and the Divisions of Materials Research and Chemistry, involves research on siloxane-type polymeric networks. Polyhedral oligosilsesquioxanes (POSS) are an interesting class of three-dimensional Si/O clusters derived from the reaction of organiosilicon monomers with water. Since their discovery in 1946, the syntheses of many well-defined POSS have been reported, but only recently have application for POSS is the production of "hybrid plastics", which combine the best features of organic polymers with the best features of ceramics. In addition to being lighter, more durable, and able to withstand higher temperatures then conventional plastics, POSS-containing plastics exhibit many other substantially improved properties. Since 1991, the Feher Group at UCI and the Lichtenhan Groups at the Air Force Research Laboratory (1991-98) and Hybrid Plastics (1998-present) have worked to develop the methodology require to manufacture POSS from inexpensive feedstocks, as well as the technology required to transform common plastics into high-performance POSS-containing plastics. The research outlined in this proposal is a natural consequence of the highly successful work by both groups over the past two years. The goal of this project is to develop a fundamental understanding of structure/property relationships for POSS-based nanoreinforced plastics. This goal will be achieved by: (1) defining and synthesizing families of POSS monomers that can be used to probe the effects of size, shape and chemical composition of the POSS additive; (2) preparing and evaluating a variety of POSS-reinforced plastics in order to establish preliminary structure/property relationships; and (3) establishing a feedback loop to test hypotheses and guide future work.
In addition to resolving many questions relating to the origin of the property enhancements observed for POSS-reinforced plastics, this project is expected to create a foundation for the development of other families of hybrid inorganic/organic polymers. There are many other three-dimensional molecules that may be suitable as nanoreinforcements or functional additives to plastics. Exploration and developmental work on these systems would be greatly facilitated by the kind of detailed structure/property relationships that should emerge from this work.
