We synthesize high-performance polymers (plastics) using a specialize technique called anionic synthesis. This synthesis technique is amenable to extremely high molecular weight polymer with narrow polydispersity index, which is useful for a number of reasons. High molecular weight provides good toughness in a polymer. Narrow polydispersity give a polymer that can be well characterized, which is useful for scientific investigations. We synthesis polymers such as poly(ethylene oxide), (CH2CH2O)n. PEO is a polar, hydrophilic polymer that can dissolve/dissociate salts. It can be used as an electrolyte, for example in lithium batteries. It is also highly selective to CO2 over other gases.
Anionic synthesis can be used to make block copolymers, which are two or more chemically different polymers covalently attached at their chain ends. The blocks tend to phase separate, but can only do so on a molecular length scale. Therefore, they form nanostructures that provide the properties of each block in a single, macroscopically homogeneous material. We are currently studying polystyrene-block-PEO, because it provides the outstanding transport properties of PEO to salt, water and CO2, while also providing an extremely tough polymer due to the glassy nature of PS. We are expert in forming polymers into membranes, which we incorporate into batteries or study for water purification/desalination or CO2 sequestration. We have all the capabilities to fully characterize a polymer, which includes gel permeation chromatography for molecular weight measurements, infrared and nuclear magnetic resonance spectroscopies for chemical characterization as well as transport measurements, electrochemical techniques for conductivity measurements and battery performance evaluation. We use electron microscopy and x-ray scattering to determine the microstructure of block copolymers and examine polymer dynamics. We have capabilities in thermal measurement techniques to evaluate thermal degradation and thermal properties such as crystallization temperature. We regularly evaluate mechanically properties using both tensile and shear techniques, such as parallel-plate rheology.
We synthesize metal nanoparticles ranging in size from several nanometers to more than 100 nm with low polydispersity. We have developed capabilities to surface functionalize these particles with a variety of small molecule ligands or polymers (both hydrophilic and hydrophobic). We use these particles as probes to examine dynamics in heterogeneous block copolymers. We also can assemble them into well-ordered, large-area monolayer films that we can deposit on any surface. These films have tunable optical and electrical properties. We are currently using them for their exceptional enhancement properties for Raman spectroscopy. With Raman spectroscopy they can used to detect trace chemicals. We use many of the same techniques that are used for polymers to characterize our nanoparticles.
We have extensive, air-free space for applications like lithium batteries. We have facilities to characterize polymer electrolyte, including ionic conductivity, battery cycling, and electrolyte degradation. We are also developing several in situ techniques that incorporate either electrochemical or mechanical excitation while monitoring the system with spectroscopy or scattering techniques.
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