Elucidation of Anomalous Domain Growth in Brush Particle Blends

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

NON-TECHNICAL ABSTRACT Polymer nanocomposites are materials that are comprised of inorganic nanomaterials dispersed within a polymer matrix. Polymer nanocomposites display unique physical properties that have rendered them a platform for innovative material technologies in areas such as energy storage and generation, transportation or biomedical. The realization of these technologies is contingent on the ability to control the material’s structure and, thus, its properties. This is hindered by the current lack of understanding of the interactions between the polymer and nanomaterial constituents and their effect on material behavior. The goal of this project is to develop novel methods to control the interactions between polymer and nanomaterial constituents and to harness these interactions to enable polymer nanocomposite materials in which structure and properties can be deliberately controlled to optimize performance. This will promote the development of scalable and economic fabrication processes for materials with improved properties. The program will support the teaching of two new courses on polymer science and engineering and provide training for one graduate student and several undergraduate student researchers. Collaborations with educators at minority serving institutions will be leveraged to support the participation of minority students. TECHNICAL ABSTRACT The modification of particle surfaces with polymer chains facilitates control of the interactions and assembly behavior of nanoparticle-based materials. The resulting brush particles have thus emerged as model systems to elucidate the physics of materials that are intermediate between the classical ‘colloidal hard sphere’ and ‘polymer coil’ limit and as a platform for the development of functional materials in areas such as self-healing, shape memory, high-k dielectrics, or thermoplastic elastomers. This research project will develop fundamental understanding of the conditions that enable polymer ligands to induce polymer-like phase behavior in (nano)particulate materials. The research will test the hypothesis that the constraining effect of the slow particle diffusion gives rise to the splitting of domain growth kinetics into two regimes: an early ‘anomalous’ regime dominated by the dynamics of grafted chains and a subsequent ‘regular’ growth regime that is governed by particle diffusion. The research plan is organized into three research thrusts that focus on the synthesis of brush particle model systems with systematically varied particle size, degree of polymerization, and density of grafted chains; the characterization of structure evolution of LCST brush particle blend systems in the thin film state as a function of molecular architecture, composition, quench depth and annealing time; and the elucidation of structure evolution of brush particle blend systems in the bulk state using X-ray and neutron scattering analysis. The program provides cross-disciplinary training for one graduate and several undergraduate students in the critical areas of polymer and nanoscale materials as well as self-assembly processes. Collaboration with researchers at minority serving institutions will promote the participation of minority students and underrepresented groups. The program will support the teaching of two new courses on polymer science and engineering as well as a summer course that is offered to high school students visiting Carnegie Mellon University as part of its AP/EA program. . This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.