Molecular Mechanisms of Failure in Polymer Nanocomposites

Suny At Stony Brook, Stony Brook NY

Investigators

Abstract

0079410 Gersappe This is an award for theoretical and computational research on polymer nanocomposites. Polymer nanocomposites are a new class of materials that are formed when nanometer sized inorganic particles (fillers) are mixed into a polymer matrix. The large surface area presented by these fillers, coupled with the ability to control the interactions between the fillers and the matrix offers the possibility of the development of a new material that can find potential applications in a wide variety of areas give their extraordinary properties: their light-weight but extremely high mechanical strength, their selective filtering capacity and their high thermal stability. Indeed, polymer nanocomposites are being touted as the next generation of materials in applications as diverse as automobile parts and bone fixation materials. Yet, a fundamental knowledge of the processes by which these small nanoscale particles enhance the strength of the material is still unknown. While advances in synthetic methods have led to a precise control of structures at the nanometer scale, the development of a theoretical framework that can predict macroscopic properties of polymers in such nanostructured environments from their microstructural details has not kept pace with the synthetic advances. This is because macroscopic assumptions break down when the critical length scale of the environment is on the order of a few molecular sizes. It is this gap that will be addressed in this research. Thus, the aim is to understand the molecular mechanisms that are responsible for the extraordinary mechanical properties of the nanocomposite. The approach to be taken here uses a combination of mean field methods and molecular dynamics simulations to extract the critical parameters necessary to bridge the gap between the nanoscale (where the critical assemblies exist) and the mesoscales (where the prediction of physical properties takes place). Numerical self-consistent field calculations combined with a netwrok formation theory will be used to focus parallel molecular dynamics simulations into those regions of phase space where one can determine the critical factors that control the response of the nanocomposite to external load. %%% This is an award for theoretical and computational research on polymer nanocomposites. Polymer nanocomposites are a new class of materials that are formed when nanometer sized inorganic particles (fillers) are mixed into a polymer matrix. The large surface area presented by these fillers, coupled with the ability to control the interactions between the fillers and the matrix offers the possibility of the development of a new material that can find potential applications in a wide variety of areas give their extraordinary properties: their light-weight but extremely high mechanical strength, their selective filtering capacity and their high thermal stability. Indeed, polymer nanocomposites are being touted as the next generation of materials in applications as diverse as automobile parts and bone fixation materials. Yet, a fundamental knowledge of the processes by which these small nanoscale particles enhance the strength of the material is still unknown. While advances in synthetic methods have led to a precise control of structures at the nanometer scale, the development of a theoretical framework that can predict macroscopic properties of polymers in such nanostructured environments from their microstructural details has not kept pace with the synthetic advances. This is because macroscopic assumptions break down when the critical length scale of the environment is on the order of a few molecular sizes. It is this gap that will be addressed in this research. Thus, the aim is to understand the molecular mechanisms that are responsible for the extraordinary mechanical properties of the nanocomposite. ***