Collaborative Research: Effect of Polymer Chemistry on Penetrant Transport in Weak Polyelectrolyte Brushes

About This Grant

This project focuses on special materials called "polymer brushes," which are tiny, hair-like chains attached to surfaces. These brushes can change how they behave based on their environment — such as changes in acidity or salt levels. Because they are low-cost, flexible, and easy to make, polymer brushes have the potential to be used in water purification and environmental sensing. However, scientists do not yet fully understand how to design these brushes to control how small molecules move in and out of them. This project will identify how characteristics of the brush — such as whether they carry an electric charge, how they interact with water, the size of the building blocks, and how many chains are present — affect their structure and behavior. The goal is to better understand how the makeup of these brushes affects their response to environmental changes and how they allow molecules and particles to pass through. Project outcomes could help improve materials used in water purification systems and biological separation processes. The project will also provide training for undergraduate and graduate students at Rice University and the University of Houston. In addition, the team will lead public outreach activities on filtration and clean water at local centers and science festivals. This project will help understand the influence of charge state on the transport of penetrants within charged polymer brushes. The team will synthesize random copolymer brushes with charged, neutral hydrophilic, and/or neutral hydrophobic monomers. Polymer structure and charge distribution in various solution conditions will be characterized using in situ (wet) ellipsometry, neutron scattering, and molecular simulation. This information will be used to test theories coupling penetrant transport, to be assessed through microscopic imaging and simulation, to the dynamics of polymer brushes under quiescent conditions. Finally, penetrant transport will be quantified under flow conditions using microfluidics and simulation. This project will thus provide the fundamental knowledge needed to molecularly design polymer brushes to control penetrant transport. This information will be used to control the local monomer interactions within brushes and thereby tailor the interfacial properties of separations and sensing devices. Results will be disseminated at local meetings that attract participants from Houston’s petrochemical, biomedical, and materials industries, including the Texas Soft Matter Meeting. The PIs will partner with the Rice Office of STEM Engagement (R-STEM) to develop outreach modules on water purification for the Energy Explorations Academy to present hands-on demonstrations at the annual Houston Energy Festival. 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.