Ph.D.: California Institute of Technology, 1993
Postdoctoral Fellow: University of Pennsylvania, 1992-94
Awards:Alfred P. Sloan Foundation Research Fellow, 1999-2001ACS PMSE/YCC Young Contributor to Polymer Materials Science, 1999Research Corporation Cottrell Teaching/Scholar Award, 1997National Science Foundation CAREER Award, 1996-20013M Non-tenured Faculty Award, 1996-2000Regents′ Junior Faculty Fellowship, U. C. Berkeley, 1996
Nanostructured Organic Materials, Polymer Chemistry, Functional Liquid Crystal Design
(1) Functional Nanostructured Polymers Based on Liquid Crystal Building Blocks
One of the most important frontiers in materials chemistry is the architectural control of synthetic materials on the nanometer-scale (1 nm = one-billionth of a meter). Nanometer-scale architecture is primarily responsible for the impressive properties of many biological structural materials (e.g., bone) and the unique reactivity of many inorganic supercage catalysts (e.g., zeolites). Unfortunately, very few techniques for constructing man-made materials offer compositional or architectural control on this size regime. One of the principal questions that we are addressing is whether materials with unique or superior bulk properties can be generated if nanometer-scale architectural control could be achieved in organic materials and polymer design to enhance or generate new functional materials properties.
We have developed a successful research program directed at constructing functional materials with controlled nanostructures by designing self-organizing monomers based on thermotropic (i.e., temperature-dependent) and lyotropic (i.e., amphiphilic; solvent-dependent) liquid crystals (LCs) (Figure 1). Through molecular design, we have been able to incorporate functional properties into the LC assemblies and subsequently polymerize them into robust polymer networks with preservation of their nanostructure. These ordered matrices serve as the basis for our new materials synthesis, as well as a platform for investigating structure–property relationships on this size regime. These new LC monomers and assemblies also serve as novel platforms for examining the effect of nanostructure on polymerization kinetics, connectivity, etc., in addition to functional properties.
Figure 1. Representations of some common thermotropic LC phases and lyotropic LC phases.
We are interested not only in the design of organic monomers with self-assembly properties but also intensely interested in the effects of engineered order on their useful bulk properties. We tailor our chemistry to provide control over nanoarchitecture, chemical composition, and processing in our new materials. These factors are crucial if these strategies are to evolve into potentially viable technologies.
Our research program in LC-based, nanostructured polymers is divided into three main directions. The first area is the development of polymerizable lyotropic LCs for the construction of functional, nanostructured polymeric materials. In this research area, we are interested in designing polymerizable :LCs to produce nanoporous polymer networks that can be used in several important materials applications areas. One area is their use as templates for making ordered nanocomposites with enhanced bulk performance. Another area is their use as catalytic organic analogues to zeolite and molecular or mesoporous sieves for heterogeneous catalysis with better activity and/or reaction selectivity as a result of their tunable nanopore sizes and environments. A third area is their development into tunable molecular size-selective membranes for applications such as water desalination and toxic vapor filtration from air. A more recent area is their use as enhanced solid ion conductors for Li battery membrane/electrolyte applications, with the possibility of expanding this new work into enhanced proton-conductors and nanostructured fuel cell membranes.
The second area involves the design of monomers based on functional thermotropic LCs to control order, symmetry, and symmetry-based bulk properties in the final polymer assembly. In this research direction, we are interested in designing new functionalized LCs and cross-linked dense polymer networks based on them for energy transducer and property amplification.
The third area is the development of new strategies for the synthesis of LCs that exhibit functional properties and new supramolecular architectures to serve as building blocks for new materials. In this area, we are primarily interested in exploring new strategies for incorporating new functional groups and properties into LCs and polymerizable LCs with preservation of their desired self-assembly properties. These molecules will be used to design new and better LC-based polymers for some of the specific applications mentioned above.
(2) Architectures Based on Room-Temperature Ionic Liquids
In addition to the design and development of new nanoporous polymer materials based on LC starting materials, our research group has recently been involved in the design and synthesis of new type of ionic organic materials based at room-temperature ionic liquids (RTILs), in collaboration with Prof. Rich Noble in the Dept. of Chemical & Biological Engineering at CU Boulder. RTILs are typically molten organic salts at room temperature (Figure 2), and they have a unique combination of properties as liquid materials, including negligible vapor pressure, high ionic conductivity, usual gas solubility properties, and even intrinsic accelerating properties for certain chemical reactions. Consequently, RTILs have been shown to be valuable as new reaction solvents and catalysts, as ion-conducting media, and as new media for light gas separations in supported liquid membranes.
Figure 2. Some functionalized, imidazolium cation-based RTILs prepared by our group and studied for light gas separation and uptake properties.
One major goal of this new area of work in our group is generate and explore new types of RTILs containing unusual or unprecedented functional groups, capabilities, and properties in order to expand the applications potential of these unique ionic solvents and liquid materials. A second major goal of our work in the RTIL materials design area is to explore new morphologies of RTIL-based organic materials, such as new polymer and LC architectures based on ionic RTIL building blocks, RTIL-based solid-liquid composites, and nanostructured polymer-RTIL solid-liquid composites. The premise of this latter work is to obtain unique materials systems and morphologies with the desirable properties of RTILs but with more robust solid-like properties for materials applications and a degree of liquid-like mobility for good transport behavior. Our initial application target for these materials is gas separations (i.e., as sorbents and membranes) because of the unique solubility selectivity properties of conventional RTILs for gases such as CO2. We also intend to examine the potential of these new types of RTIL-based materials in other application areas where fluid ions in a solid matrix would be beneficial (e.g., lubrication under extreme conditions, non-aqueous ion conduction, catalysis of organic reactions in unusual environments).
Functional Nanostructured Polymers Based on Liquid Crystal Building Blocks:
Kerr, R. L.; Miller, S. A.; Shoemaker, R. K.; Elliott, B. J.; Gin, D. L. “New Type of Li Ion Conductor with 3D Interconnected Nanochannels via Polymerization of a Liquid Organic Electrolyte-Filled Lyotropic Liquid-Crystal Assembly,” J. Am. Chem. Soc. 2009, 131 (44), 15972–15973.
Pecinovsky, C. S.; Hatakeyama, E. S.; Gin. D. L. “Polymerizable Photochromic Macrocyclic Metallomesogens: Design of Supramolecular Polymers with Responsive Nanopores,” Adv. Mater. 2008, 20 (1), 174–178.
Zhou, M.; Nemade, P. R.; Lu, X.; Zeng, X.; Hatakeyama, E. S.; Noble, R. D.; Gin, D. L. “New Type of Membrane Material for Water Desalination Based on a Cross-linked Bicontinuous Cubic Lyotropic Liquid Crystal Assembly,” J. Am. Chem. Soc. 2007, 129 (31), 9574–9575.
Lu, X.; Nguyen, V.; Zhou, M.; Zeng, X.; Jin, J.; Elliott, B. J.; Gin, D. L. “Cross-linked Bicontinuous Cubic Lyotropic Liquid Crystal–Butyl Rubber Composites: Highly Selective, Breathable Barrier Materials for Chemical Agent Protection,” Adv. Mater. 2006, 18 (24), 3294–3298.
Pecinovsky, C. S.; Nicodemus, G. D.; Gin, D. L. "Nanostructured, Solid-state Organic, Chiral Diels–Alder Catalysts via Acid-induced Liquid Crystal Assembly," Chem. Mater. 2005, 17 (20), 4889–4891.
Martin, A. G.; Harms, S.; Weigand, W.; Gin, D. L. "Polymerizable Transition-metal-containing Liquid Crystals with Thermally Reactive 1,3-Diene Tails," Adv. Mater. 2005, 17 (5), 602–606.
Hoag, B. P.; Gin, D. L. "Polymerizable Hexacatenar Mesogens Containing a Luminescent Oligo(p-phenylenevinylene) Core," Liq. Cryst. 2004, 31 (2), 185–199.
Xu, Y.; Gu, W.; Gin, D. L. "Heterogeneous Catalysis Using a Nanostructured Solid Acid Resin Based on Lyotropic Liquid Crystals," J. Am. Chem. Soc. 2004, 126 (6), 1616–1617.
Sentman, A. C.; Gin, D. L. "Polymerizable Bent-core Mesogens: Switchable Precursors to Ordered Polar Polymer Materials," Angew. Chem. Int. Ed. 2003, 42 (16), 1815–1819.
Gin, D. L.; Gu, W.; Pindzola, B. A.; Zhou, W.-J. "Polymerized Lyotropic Liquid Crystal Assemblies for Materials Applications," Acc. Chem. Res. 2001, 34, 973–980. (invited review article)
Gu, W.; Zhou, W.-J.; Gin, D. L. "A Nanostructured, Scandium-Containing Polymer for Heterogeneous Lewis Acid Catalysis in Water," Chem. Mater. 2001, 13 (6), 1949–1951.
Miller, S. A.; Kim, E.; Gray, D. H.; Gin, D. L. "Heterogeneous Catalysis with Cross-linked Lyotropic Liquid Crystal Assemblies: Organic Analogues to Zeolites and Mesoporous Sieves," Angew. Chem. Int. Ed. 1999, 38 (20), 3021–3026.
Smith, R. C.; Fischer, W. M.; Gin, D. L. "Ordered Poly(p-phenylenevinylene) Matrix Nanocomposites via Lyotropic Liquid-Crystalline Monomers," J. Am. Chem. Soc. 1997, 119 (17), 4092–4093.
New Ionic Materials and Polyelectrolyte Architectures Based on Room-Temperature Ionic Liquids:
Bara, J. E.; Camper, D. E.; Gin, D. L.; Noble, R. D. “Room-temperature Ionic Liquids and Composite Materials: Platform Technologies for CO2 Capture,” Acc. Chem. Res. 2010, 43 (1), 152–159. (invited review article)
LaFrate, A. L.; Bara, J. E.; Gin, D. L.; Noble, R. D. “Synthesis of Diol-functionalized Imidazolium-based Room-temperature Ionic Liquids with Bis(trifluoromethanesulfonimide) Anions that Exhibit Switchable Water Miscibility,” Ind. Eng. Chem. Res. 2009, 48 (18), 8757–8759.
Voss, B. A.; Bara, J. E.; Gin, D. L.; Noble, R. D. “Physically Gelled Supported Ionic Liquid Membranes with Enhanced CO2 Gas Transport,” Chem. Mater. 2009, 21 (14), 3027–3029.
Bara, J. E.; Hatakeyama, E. S.; Gin, D. L.; Noble R. D. “Improving CO2 Permeability in Polymerized Room-Temperature Ionic Liquid Gas Separation Membranes through the Formation of a Solid Composite with a Room-Temperature Ionic Liquid,” Polym. Adv. Technol. 2008, 19, 1415–1420.
Camper, D.; Bara, J. E.; Gin, D. L.; Noble, R. D. “Room-Temperature Ionic Liquid–Amine Solutions: Tunable Solvents for Efficient and Reversible Capture of CO2,” Ind. Eng. Chem. Res. 2008, 47 (21), 8496–8498.
Bara, J. E.; Lessmann, S.; Gabriel, C. J.; Hatakeyama, E. S.; Noble, R. D.; Gin, D. L. “Synthesis and Performance of Polymerizable Room Temperature Ionic Liquids as Gas Separation Membranes,” Ind. Eng. Chem. Res. 2007, 46 (16), 5397–5404.