Self-Assembly of Polymer Brush Nanoparticles into Porous Supercrystals

University Of Utah, Salt Lake City UT

Investigators

Abstract

Porous materials are used extensively in applications ranging from environmental remediation to biosensing and drug delivery. One challenge in creating new types of porous materials is controlling the size of the pores, especially when the desired size is several hundred nanometers, or about 1000 times smaller than a human hair. With the support of the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division and the Solid State and Materials Chemistry Program in the Division of Materials Research, Professors Zharov and Gruenwald at the University of Utah are developing new strategies for designing and creating nanoporous materials. Their approach attaches polymers onto spherical nanoparticles, which are then assembled into supercrystals that resemble marbles packed into a box. The supercrystal structures observed in the laboratory are compared with computer simulations to better understand the factors that give rise to different material properties, such as porosity, strength, and flexibility. In addition to developing new ways to make nanoporous materials, the project trains graduate and undergraduate students in a collaborative research environment. The research team is also engaged in the local community, working with The Leonardo, a museum in downtown Salt Lake City, to develop energy focused activities for local K-12 students. The project is focused on preparing a series of short polymer brush nanoparticles (SPNPs) with varying architecture. The researchers are investigating their self-assembly as a function of SPNP structural parameters (i.e. size, grafting densities, polymer chemistry, and chain length) and assembly conditions. The structure, mechanical properties, and porosity of SPNP assemblies are characterized by a range of experimental methods, including transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), and Brunauer?Emmett?Teller (BET) analysis. These experimental studies shed light on correlations between parameters of the polymer brush and properties of the resulting assembled superstructures. Molecular dynamics computer simulations, using efficient coarse-grained pair potentials, connect the microscopic structure of the polymer chains to the nanoparticle assembly. In addition, the computer models provide a deeper understanding of the experimental findings, as they guide the exploration of the parameter space associated with the polymer brushes. Professor Zharov is developing and directing materials- and energy-focused hands-on and inquiry-based activities at The Leonardo, a museum in downtown Salt Lake City as part of the outreach activities associated with this project.