Role of Interface Interpenetration and Domain Size on Dynamic Coupling Across Dissimilar Polymer Domains

Emory University, Atlanta GA

Investigators

Abstract

NON-TECHNICAL SUMMARY: Advanced materials design for technological applications such as ion conduction, filtration, photoelectric generation, or composite reinforcement is focused on combining different material components at the nanoscale level. This creates systems where nearly all parts are near an interface making the resulting performance primarily dependent on the local material properties near these interfaces. Recent observations have demonstrated an unanticipated strong coupling of dynamics across dissimilar polymer interfaces established during final materials processing and interface formation. The planned research aims to understand what controls this dynamical coupling across dissimilar polymer domains and how interfaces mediate this behavior. Experiments on simplified systems using a series of different techniques will be carried out to investigate what property changes take place in multilayer systems during interface formation and how they alter the dynamics across the material. Integrated with this research will be education of students as well as outreach. Outreach efforts by the PI involve a partnership with Emory's Carlos Museum education programs to develop STEAM (Science, Technology, Engineering, Arts and Mathematics) programing for teachers and school groups covering scientific concepts used by ancient cultures such as historical water management strategies. In collaboration with the Museum's Chief Conservator, undergraduate research projects will characterize polymer resins and their applications used in artwork conservation. TECHNICAL SUMMARY: The planned research aims to understand what controls dynamical coupling across dissimilar polymer domains and how interfaces mediate this behavior. Experiments on simplified systems using a series of different techniques will be carried out to investigate what property changes take place in multilayer systems during interface annealing that alter the dynamics across the material. Comparison of results using multiple experimental techniques on a given system will provide a fuller picture of the relevant phenomena and thus facilitate improved understanding. Experiments on multilayer films with varying layer thicknesses will be done using the following techniques: quartz crystal microscopy to investigate changes in shear wave propagation across dissimilar polymer interfaces upon progressive interface annealing, ellipsometry to study changes in physical aging due to the impact of glassy-rubbery polymer interfaces, and differential scanning calorimetry to compare glass transition breadths and temperature-dependent heat capacities. Results from these techniques will be correlated or contrasted to localized depth-dependent measurements of the glass transition temperature using fluorescence on equivalent systems. The goals of this project are to address which experimentally measurable factors change during interface formation leading to dynamical coupling between different polymer domains, and how finite domain sizes (changing boundary conditions) alter this phenomenon. . 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.