I. New Methods for the Chain-Growth Synthesis of p-Conjugated Polymers
Organic p-conjugated polymers are promising materials for thin-film solar cells, light-emitting diodes, and transistors because they exhibit tunable optical and electrical properties and can be solution-processed onto large, flexible substrates. However, these materials have several limitations and synthetic methods that provide access to new polymers are needed. Although a Ni-catalyzed chain-growth method was recently reported, the narrow substrate scope, highly monomer-specific reaction conditions, and inefficient cross-propagation between two monomers has limited its utility. My group’s approach to overcome these challenges has involved (i) elucidating the chain-growth mechanism and competing reaction pathways and (ii) developing alternative ligands/catalysts for improved reactivity.
II. Synthesis and Characterization of Gradient p-Conjugated Copolymers
Organic p-conjugated polymers are an increasingly important class of materials because of their widespread application in electronic devices. Although there have been extensive studies aimed at controlling their physical, optical and electronic properties through synthetic modifications, processing conditions, and device designs, little is known about the effect of copolymer sequence because these materials have been synthetically inaccessible. The ability to tailor properties by simply altering the copolymer sequence should provide a powerful new design strategy for preparing the next-generation of tunable organic materials. We have been targeting gradient copolymers, which exhibit continuously changing composition along the polymer chain, because of their anticipated ability to stabilize polymer blends. These novel copolymers will exhibit unique physical, optical and electronic properties when self-assembled in solution and blended in films.
III. Developing Stimuli-Responsive Materials based on Gelation
Molecular gels are increasingly being investigated for diverse applications, including chemical sensing, bioresponsive materials, regenerative medicine, and environmental remediation. Despite these successes, recent efforts to either improve gel properties or extend their applications have been significantly limited because gelation remains a largely unpredictable phenomenon. It was recently estimated that over 1000 small-molecule based gelators have been reported in the literature, although most of these gelators were either discovered serendipitously or through extensive combinatorial screening methods. It has been difficult to elucidate design principles from this data set because seemingly subtle changes to these gelator structures have had unpredictable and often detrimental effects on their gelation ability. My group’s approach to overcome these challenges has involved (i) creating, testing, and modifying a new gelator design strategy and (ii) identifying the key structure-property relationships relevant to gelation.
Class of 1923 Memorial Teaching Award, 2013
Camille Dreyfus Teacher-Scholar Award, 2012
LSA Excellence in Education Award, 2011
NSF Career Award, 2010
PECASE Award - Presidential Early Career Awards for Scientists and Engineers, 2010
Beckman Young Investigator Award, 2009
Chemistry Faculty Research Award, 2009
Office of Naval Research Young Investigator Award, 2009
Seyhan N. Ege Junior Faculty Award, 2009
Thieme Chemistry Journal Award, Synthesis and Synlett, 2009
Elizabeth Caroline Crosby Research Award, 2008
William R. Roush Junior Faculty Career Development Award, 2008
Bremmer, S. C.; Chen, J.; McNeil, A. J.; Soellner, M. B. A General Method for Detecting Protease Activity via Gelation and its Application to Artificial Clotting. Chem. Commun. 2012, 48, ASAP.
Bryan, Z. J.; Smith, M. L.; McNeil, A. J. Chain-growth Polymerization of Aryl Grignards Initiated by a Stabilized NHC-Pd Precatalyst. Macromol. Rapid Commun. 2012, 33, ASAP.
Lee, S. R.; Bryan, Z. J.; Wagner, A. M.; McNeil, A. J. Effect of Ligand Electronic Properties on Precatalyst Initiation and Propagation in Ni-catalyzed Cross-coupling Polymerizations. Chem. Sci. 2012, 3, 1562-1566.
Adhia, Y. J.; Schloemer, T. H.; Perez, M. T.; McNeil, A. J. Using Polymeric Additives to Enhance Molecular Gelation: Impact of Poly(acrylic acid) on Pyridine-based Gelators. Soft Matter 2012, 8, 430-434.
Muro-Small, M. L.; Chen, J.; McNeil, A. J. Dissolution Parameters Reveal Role of Structure and Solvent in Molecular Gelation. Langmuir 2011, 27, 13248-13253.
Moy, C. L.; Kaliappan, R.; McNeil, A. J. Aryl Trihydroxyborate Salts: Thermally Unstable Species with Unusual Gelation Abilities. J. Org. Chem. 2011, 76, 8501-8507.
Lanni, E. L.; Locke, J. R.; Gleave, C. M.; McNeil, A. J. Ligand-based Steric Effects in Ni-catalyzed Chain-growth Polymerizations using Bis(dialkylphosphino)ethanes. Macromolecules 2011, 44, 5136-5145.