DMREF: Engineering Organic Glasses

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TECHNICAL SUMMARY: With support from the NSF DMR under the Materials Genome Initiative, Lian Yu, Mark Ediger, Juan de Pablo, and their coworkers will study Engineering Organic Glasses. Glasses constitute an important class of materials that combine the advantages of solids, including mechanical stability, with the advantages of liquids, including macroscopic spatial uniformity, making them ideal for a wide range of applications. Glasses, however, are inherently non-equilibrium materials, which makes their study and design particularly challenging. While familiar glasses are inorganic and polymeric, organic glasses of relatively low molecular weights are finding applications in electronics, bio-preservation, and drug delivery. The team seeks to create a knowledge base and develop design principles for the engineering of organic glasses. The effort builds on previous progress in the engineering of crystals and inorganic glasses, as well as recent discoveries in the field of organic glasses, in particular, the creation of high-density and high-stability glasses with tunable anisotropy by physical vapor deposition (PVD). A concerted program of experiments and simulations will target three areas of organic glass engineering that have technological relevance and where current understanding is lacking: (1) controlling anisotropy, (2) controlling molecular conformation, and (3) inhibiting crystallization. Under Aim 1, the team will study the creation and control of anisotropy in organic glasses by PVD, external fields, and liquid-crystal order. Though often isotropic, glasses with controlled anisotropy have potential applications in data storage, non-linear optics, and laser technologies. Work under Aim 2 seeks to produce organic glasses while actively controlling molecular conformation. Conformational flexibility characterizes many molecular components of organic glasses; controlling conformation offers a unique opportunity in optimizing their properties (e.g., HOMO/LUMO levels and charge mobility). Under Aim 3, the team will stabilize organic glasses against crystallization using polymer additives. This capability will enable promising but easy-to-crystallize organic glasses to serve as durable amorphous materials. Work in all areas will be performed in a high-throughput manner, with simulations used to screen the selection of materials and conditions for experimentation, and to interpret experimental data. NON-TECHNICAL SUMMARY:Glasses are amorphous materials that combine solid-like mechanical stability and liquid-like spatial uniformity, making them ideal for many applications ranging from telecommunication to bio-preservation. This research seeks to advance the science and technology of organic glasses, and the results will provide a foundation for designing organic glasses with desired properties through concerted use of simulations and targeted experiments. This research will benefit materials scientists and engineers in other fields where glasses and amorphous materials are important, and contribute to a broader perspective on the science of glasses in general. The improved ability to stabilize amorphous materials against crystallization will especially benefit pharmaceutical scientists as they develop amorphous formulations to deliver highly potent but poorly soluble drugs. Poor solubility is limiting the development of many drugs that would significantly advance health care in the U.S. and developing countries. In addition to journal publications, results from this work will be disseminated via a central website, a mechanism especially important for archiving and sharing the extensive data from high-throughput investigations.Graduate and undergraduate students will benefit from the multi-disciplinary nature of this project, having significant exposure to simulations and experiments, crystals and glasses, and polymeric and low-molecular-weight materials. Personnel supported by this grant will work with UW-Madison's Pre-college Enrichment Opportunity Program for Learning Excellence (PEOPLE), which has a proven record of increasing the enrollment of minority and low-income high school students in colleges and universities. This program provides experiences that help students to become scientifically literate citizens and encourages them to consider careers in science and engineering.