Inter-American Materials Collaboration: Designing Acrylic Coatings Using Mechanistic Modeling

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This Inter-American Materials Collaboration research project is carried out by Linda Broadbelt, Northwestern University, and Robin Hutchinson, Queen's University, Canada. The long-term objective of this research is to improve industrial polymerization processes and to contribute to the design of new polymeric materials by developing a deeper understanding of free-radical polymerization kinetics and capturing that knowledge in modeling-based tools. The production of solvent-borne acrylic resins for the coatings industry has been chosen as a focal point for the effort. Acrylic resins, the base polymer for many coatings, are now produced with lower solvent levels and at higher temperatures than before. Little is known about the high-temperature secondary reactions that play an important role in controlling rate and molecular structure, which in turn determines the end-use properties and product value of the polymers produced. This research provides a methodology to estimate the kinetic parameters required to apply the model to a broad range of polymerization systems where the complete set of rate coefficients may not have been determined experimentally. To this end, this project uses a collaborative, three-pronged approach requiring the expertise of both groups at Queen's and Northwestern Universities. First, a detailed examination of poly(butyl acrylate) structure, synthesized under carefully controlled conditions, will be carried out (Queen's University). These results are combined with mathematical modeling to refine the mechanistic pathway and quantify the kinetics of these secondary reactions (Queen's University and Northwestern University). Second, a general model applicable for high-temperature synthesis of free-radical copolymers is constructed (Queen's University and Northwestern University) and tested against lab scale experimental data (Queen's University) for a styrene/acrylate/methacrylate terpolymer. Finally, molecular modeling is examined as a tool for the a priori prediction of relative rate coefficients (Northwestern University).The potential impact of the proposed research on industrial formulation and production of coatings is high. This work, if successful, will provide the methodology of how to populate databases of rate coefficients for a suite of potential monomers used in acrylic coatings. Coatings are a major cost in the automotive sector and other industries, and any advancement that can reduce costs or improve performance has an impact. The education value of the proposed international collaboration is also high. The graduate students involved in this work are exposed to a wide range of experimental techniques involving polymer synthesis and characterization, become proficient in critical data analysis and in the development and application of fundamental models to interpret experimental data and to improve manufacturing processes, and develop expertise in the application of computational chemistry tools. Through the collaboration with investigators in Canada, students interact with international experts in polymerization, including industrial scientists, and develop improved communication skills. This award is supported by the Division of Materials Research, the Division of Chemical and Transport Systems, the Office of International Science and Engineering, and the Office of Multidisciplinary Activities in the Directorate for Mathematical and Physical Sciences.