Collaborative Research: GOALI: Design of Chemically Self-Regulated, Acrylic Coatings Processes through Iterative Use of Chemical Quantum Calculations and Spectroscopic Methods

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

0932786 Rappe Intellectual Merit The PIs' previous study of free-radical solution homo- and co-polymerization of a class of alkyl acrylates, such as ethyl and n-butyl acrylates, revealed very substantial, spontaneous thermal polymerization at 120-180oC in the absence of added thermal initiators. Monomers such as styrene and many methacrylates, not alkyl acrylates, had been known to undergo spontaneous polymerization. In their work, they carried out laboratory experiments and identified several factors influencing the initiation step in the spontaneous polymerization. They have also made advances in efficiently using chemical quantum-level computations on supercomputers to study the kinetics of polymerization reactions. Building on these successes, they plan to employ an iterative research strategy that includes first-principles density functional theory (DFT) calculations, design of experiments, batch laboratory experiments, and spectroscopic analyses. It is aimed at quantitatively understanding the kinetics, the reaction mechanisms, and the relevant intermediates and transition states for initiation and chain transfer in spontaneous thermal polymerization of methyl, ethyl, and n-butyl acrylates using this integrated research strategy, with the ultimate goal of designing "chemically self-regulated" polymerization processes for the production of high-performance acrylic resins. It will involve a broad spectrum of activities such as: (i) proposing initiation model mechanisms, (ii) estimating molecular geometries of reactants, transitions states, intermediates, and products using DFT calculations on supercomputers, (iii) validating and calculating reliable thermo chemistry using Gaussian-n theory, (iv) designing laboratory batch polymerization experiments to capture the initiating and product species and to verify the controlling nature of the species and mechanisms, (v) conducting polymerization experiments, (vi) conducting spectroscopic analyses, (vii) comparing end group structures from the chemical quantum calculations and spectroscopic analyses, (viii) calculating reaction rate coefficients from the quantum chemical data, (ix) comparing the theoretical predictions with values obtained from the experiments, and (x) validating the control living species. Broader Impacts The potential impacts of this project are societal (through improved safety), environmental, economic, and in human resource development. Spontaneous thermal polymerization allows for the production of higher quality, environmentally-friendlier solvent-borne paints and coatings at lower operating costs. Low molecular weight, polymer and oligomer solutions even at high weight percent solids have adequately low viscosity, thus requiring less organic solvents to be sprayable and brushable. The use of less or no added thermal initiators (normally the most expensive component of a resin formula) and significantly shorter reaction times lower the operating costs. The presence of less residual groups from azonitrile and organic peroxides thermal initiators (which adversely affect polymer properties such as resistance to UV radiation) in the final product and the use of the quantitative understanding in optimal control of molecular properties improve the resin quality. The PI and Co-PIs will train and mentor two doctoral research assistants as well as six undergraduate (REU) students, who will participate in broad range of research activities from quantum-level computations and supercomputing to laboratory experiments and spectroscopic methods, some of which will be conducted at DuPont Marshall Laboratory. The project results will be released to the public at conferences and in journal and conference proceedings papers. Students from under-represented groups will be selected, trained and mentored in this project.