Modified POSS Polymers for Stone Conservation

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TECHNICAL ABSTRACTThe intellectual merit of this SCIART research is in developing practical syntheses of polymers for stone consolidation that possess "nano-to-macro" length scales similar to that of natural stone. By utilizing both nano (POSS, 1nm-10nm) and macroscopic length (polymer) scales in a conservation and consolidation system, a continuation of length scale and properties with those in natural stone can be achieved thus strengthening the stone. POSS silanols show the ability to coordinate a large number of chemical compounds; however their interaction with natural stone surfaces is poorly understood. For POSS silanols, we seek a fundamental understanding of the POSS-silanol/stone interfacial interactions -- an understanding that may lead to the design of high performance stone consolidants -- particularly for calcium carbonate stones where state-of-the-art sol-gels fail. A novel approach to stone consolidation is developed using POSS-silanol/thiol-X systems (where X represents an -ene, (meth)acrylates, vinyl ethers, etc.) which can be applied to stone as liquid monomer resins (improving depth of penetration) and cured via frontal photopolymerization (FPP). From this approach, the PIs seek to develop structure-property relationships of the POSS/thiol-X materials such that critical parameters, i.e. the glass transition temperature, modulus, CTE, and index of refraction can be matched to a particular stone type. The role of POSS-silanol on interfacial adhesion and POSS/thiol-X resins on surface energy, water vapor transport, and porosity are of fundamental importance and will be elucidated.NON-TECHNICAL ABSTRACT Treatment of stone deterioration is a complex process that must take into consideration the stone composition and structure, the nature of the polymeric treatment, the interaction between stone and treatment, and the long term effects on the heterogeneous matrix created by the treatment on stone. It is the aim of this work to develop an advanced stone conservation approach based on POSS-silanol polymer systems designed to improve stone consolidation and water repellency.The societal implications of the research will range from the development of fundamental understanding of polymer interactions with stone surfaces to the ultimate realization of new materials technology for the conservation of America's cultural heritage. The interdisciplinary nature of this project will provide a unique opportunity for graduate and undergraduate polymer science students to experience direct interaction and collaboration with 1) an industrial leader in nanomaterials (Hybrid Plastics) and 2) the only preservation research and technology center (National Center for Preservation and Training Technology, NCPTT) within the U.S. National Park Service. A significant outreach and dissemination plan involves K-12 hands-on polymer science activities directed at conservation of cultural heritage items and the development of webinar/podcast to broaden awareness of the grand challenges facing conservation scientists and disseminate the results of this research.