Many challenging problems in the modern science and technology are related to preparation, properties, and utilization of novel functional materials. The polymer chemistry and the chemical microelectronics programs represent parts of the multidisciplinary effort in this field. The many-pronged approach includes: synthesis and molecular characterization of well-defined block and graft copolymers; preparation of new engineering thermoplastics and liquid crystalline materials; synthesis, modification and processing of polymers in super-critical carbon dioxide; chemical design of hybrid polymers for catalysis and photoredox activity, polymers for microelectronics applications including 193 nm and 157 nm photoresists and low-k dielectrics, and defined microstructures.
Chemical microelectronics is focused on preparation of organic and inorganic electronic materials; microscopic patterning of thin films using novel techniques, plasma, ion beam, laser beam, etc.; kinetics of etching and film formation; characterization of mechanical, electronic, and optical properties; spatially resolved chemical analysis of surfaces, interfaces, and thin films and microstructures. A broad variety of expertise includes visualization and probing of submicrometer surface structures by scanning probe microscopy, characterization of polymer dynamics by NMR techniques and light scattering, measurement of molecular conductivity, and analytical as well as computational and numerical methods in polymers.
Researchers in the Ashby and Sheiko groups have fabricated textured surfaces capable of reversibly changing in response to a thermal stimulus. These surfaces are fabricated with PRINT© molds provided by the DeSimone Lab, and could find use in applications requiring modular surface wetting or roughness. Reversibly switching topography on micrometer length scales greatly expands the functionality of stimuli-responsive substrates.
In an article published in ACS Applied Materials & Interfaces the groups report the first usage of reversible shape memory for the actuation of two-way transitions between microscopically patterned substrates, resulting in corresponding modulations of the wetting properties. Reversible switching of the surface topography is achieved through partial melting and recrystallization of a semi-crystalline polyester embossed with microscopic features. This behavior is monitored with atomic force microscopy, AFM, and contact angle measurements. The groups demonstrate that the magnitude of the contact angle variations depends on the embossment pattern.
The synthesis of prodrugs is a common approach to overcome drug delivery issues, including poor aqueous solubility or permeability, and to provide site-specific release. Nanotechnology can be a powerful tool to improve drug delivery, but does so by altering the biodistribution of the encapsulated small molecule. In a report published in NanoLetters, researchers in the DeSimone Group, in collaboration with a number of Centers, Institutes, and Departments here at UNC, combined the merits of both approaches to improve the pharmacokinetics and toxicity of the chemotherapeutic docetaxel by passively targeting an encapsulated docetaxel prodrug to solid tumors, where it could selectively release and convert to active docetaxel.
The Group used PRINT technology, Particle Replication in Nonwetting Templates, to prepare nanoparticles to passively target solid tumors in an A549 subcutaneous xenograft model. An acid labile prodrug was delivered to minimize systemic free docetaxel concentrations and improve tolerability without compromising efficacy.
Switchable Micropatterned Surface Topographies Mediated by Reversible Shape Memory. Sara A. Turner, Jing Zhou, Sergei S. Sheiko, and Valerie Sheares Ashby. ACS Appl. Mater. Interfaces, 2014, 6 (11), pp 8017–8021.
Particle Replication in Nonwetting Templates Nanoparticles with Tumor Selective Alkyl Silyl Ether Docetaxel Prodrug Reduces Toxicity. Kevin S. Chu, Mathew C. Finniss, Allison N. Schorzman, Jennifer L. Kuijer, J. Christopher Luft, Charles J. Bowerman, Mary E. Napier, Zishan A. Haroon, William C. Zamboni. Nano Lett., 2014, 14 (3), pp 1472–1476.
Controlling Molecular Weight of a High Efficiency Donor-Acceptor Conjugated Polymer and Understanding Its Significant Impact on Photovoltaic Properties. Wentao Li, Liqiang Yang, John R. Tumbleston, Liang Yan, Harald Ade, and Wei You. Adv. Mat., First published online, 14 MAR 2014, DOI: 10.1002/adma.201305251.
The Influence of Molecular Orientation on Organic Bulk Heterojunction Solar Cells. John R. Tumbleston, Brian A. Collins, Eliot Gann, Wei Ma and Harald Ade, Liqiang Yang, Andrew C. Stuart and Wei You. Nature Photonics (2014) doi:10.1038/nphoton.2014.55.
Copolymerization of Metal Nanoparticles: A Route to Colloidal Plasmonic Copolymers. Kun Liu, Ariella Lukach, Kouta Sugikawa, Siyon Chung, Jemma Vickery, Heloise Therien-Aubin, Bai Yang, Michael Rubinstein, and Eugenia Kumacheva. Angewandte Chemie International Edition, Volume 53, Issue 10, pages 2648–2653, March 3, 2014.
Storage of Electrical Information in Metalâ€“Organic-Framework Memristors. Seok Min Yoon, Scott C. Warren, and Bartosz A. Grzybowski. Article first published online: 14 MAR 2014, DOI: 10.1002/anie.201309642.
Self-Healing of Unentangled Polymer Networks with Reversible Bonds. Evgeny B. Stukalin, Li-Heng Cai, N. Arun Kumar, Ludwik Leibler, and Michael Rubinstein. Macromolecules, 2013, 46 (18), pp 7525â€“7541.
Nonflammable Perfluoropolyether-Based Electrolytes for Lithium Batteries. Dominica H. C. Wong, Jacob L. Thelen, Yanbao Fu, Didier Devaux, Ashish A. Pandya, Vincent S. Battaglia, Nitash P. Balsara, and Joseph M. DeSimone. PNAS, Online: DOI10.1073/pnas.1314615111.
Synthetically Encoding 10 nm Morphology in Silicon Nanowires. Joseph D. Christesen, Christopher W. Pinion, Erik M. Grumstrup, John M. Papanikolas, and James F. Cahoon. Nano Lett., 2013, 13 (12), pp 6281â€“6286.
Nanoparticle Drug Loading as a Design Parameter to Improve Docetaxel Pharmacokinetics and Efficacy. Kevin S. Chu, Allison N. Schorzman, Mathew C. Finniss, Charles J. Bowerman, Lei Peng, James C. Luft, Andrew J. Madden, Andrew Z. Wang, William C. Zamboni, Joseph M. DeSimone. Biomaterials, Volume 34, Issue 33, November 2013, Pages 8424â€“8429.