Our research is focused on polymeric materials and their application to the production of nanostructures and biomaterials. Understanding how surface chemical and physical structure relates to the properties is key to understanding and therefore designing material interfaces. Analysis techniques useful for this research include X-ray photoelectron spectroscopy, Reflectance and Attenuated Total Internal Reflection Infrared Spectroscopy, and Dynamic Contact Angle which give knowledge of the chemical nature of a surface. To determine topographical and topological structure, techniques such as Atomic Force Microscopy and Scanning Electron Microscopy are used.
Electrospinning is a technique used to produce ultrafine polymeric fibers. Reports have been made of this method producing fibers with diameters as low as 6 nm. An electric field is used to draw fibers out of a conductive polymeric solution. The method is fast and has high throughput compared to other fiber producing methods. There are few limitations on the types of fibers that can be produced. Solids can be loaded into the solutions, multiple solution can be electrospun at once to produce a composite fiber and after further processing steps the final fibers can be metals, polymers, ceramics or even semiconductors.
The range of applications is nearly endless for the fibers produced by electrospinning, from biological applications such as tissue engineering to consumer products such as textiles, or air and water filtration systems. Other engineering applications include ceramics for composite reinforcement, metal for transistors, or semiconductors. Much work has been done in the area of metal oxide ceramic fibers from polymer precursors, but we have developed a method to obtain non-oxide ceramic nanofibers from polymer precursors.
Novel Bactericidal Polymers
Hydrophobic quaternary salts, have shown anti-bacterial properties against gram-positive and gram-negative bacteria and even against drug-resistant strains. Unfortunately, these materials are not water-soluble and have poor biocompatibility. Youngblood's group is trying to improve these traits so that these materials may be incorporated in applications such as contact lenses, dental materials, and water-soluble disinfectants. As a side result of these improvements, the custom-designed polymers that his group has synthesized show about a ten-fold increase in bactericidal activity over the un-hydrophilized bactericidal polymer.
Our research focuses on stimuli-responsive behavior of polymeric materials. By altering the functionality or surface energy of the constituents of pre-synthesized block copolymers, new materials can be created with predictable solvent selectivity. Solvent selective materials created in our lab include linear polymers, networked elastomers, hydrogels, and polymer brushes with applications ranging from anti-fogging and anti-fouling surfaces to selective water/oil filters. Polymer brushes have advantages in creating stimuli-responsive surfaces or surfaces with well controlled nano-scale features. The ability to carefully design the chain length, grafting density, and chemical composition of the brushes along with the freedom to use a variety of substrates allows for a wide range of potential applications.
Organic Based Thin Films and Coatings
We are interested in using various molecular architectures in ultrathin films to alter the surface properties of bulk materials. Thin films are useful to control the surface energy of a material rendering it either hydrophobic or hydrophilic while still maintaining overall bulk properties (such as structural integrity). In addition we have created thin films for the purpose of adhesion of unlike materials such as the covalent attachment of gold nanoparticles to polyethylene-terephthalate or the adhesion of polymer films on silica. Furthermore, we have optimized and characterized the deposition kinetics of various systems of organo-silanes.
Our research efforts are focused on achieving a better understanding of adhesion in novel applications, as well as finding solutions to improve slow curing formulations and increase adhesion towards substrates that traditionally are joined through methods other than adhesive bonding. Commonly known influential factors in the preparation of an adhesive joint include the adherend roughness, its surface chemistry, interfacial characteristics at the joint and molecular orientation at the surface (wetting) among others.
The use of adhesives in all aspects of life and industry has generated an increased demand for bonding materials with outstanding strength, fast, simple application and durability. Although the presently available adhesive technologies suit most bonding needs in modern construction, manufacturing and everyday use, there is always the need for further improvement and development of new application fields. Some of these new applications require substrate-specific adhesives which can provide robust bonding and low set times. If broader substrate versatility is required, these applications could also benefit from adhesives that adhere well to a variety of substrates, but perform at lower levels of ultimate performance.
“Anisotropic Wetting on tunable Micro-Wrinkled Surfaces," Chung, J.Y.; Youngblood, J. P.; Stafford, C. M. Soft Matter (ISI Impact = new journal, not enough data), accepted pending revision.
"Oil-repellent Anti-Fog Surfaces via Stimuli-Responsive Polymer Brushes," Howarter, J. A.; Youngblood, J. P., Advanced Materials (ISI Impact = 9.107), accepted pending revision.
"Surface Modification of Polymers with 3-Aminopropyltriethoxysilane as a General Pretreatment for Controlled Wettability," Howarter, J. A.; Youngblood, J. P., Macromolecules (ISI Impact = 4.024) 2007, 40, 1128-1132. times cited: 0.
"Synergistic Activity of Hydrophilic Modification in Antibiotic Polymers," Sellenet, P. H.; Allison, B.; Applegate, B. M.; Youngblood, J. P. Biomacromolecules (ISI Impact = 3.618) 2007, 8(1), 19-23. times cited: 0.
"Optimization of Silica Silanization by 3-Aminopropyltriethoxysilane." J.A. Howarter and J. P. Youngblood. Langmuir 2006, 22(26): 11142-11147.
“Coatings Based on Side-chain Ether-linked Poly(ethylene glycol) and Fluorocarbon Polymers for the Control of Marine Biofouling” Youngblood, J.P.; Andruzzi, L.; Ober, C.K; Hexemer, A.; Kramer, E.J.; Callow, J.A.; Finlay, J.A.; Callow, M.E Biofouling 2003, 19, 91.
“Plasma Polymerization of Solid Phase Polymer Reactants (Non-Classical Sputtering of Polymers)” Youngblood, J.P.; McCarthy, T.J. Thin Solid Films 2001, 382, 95.
“Ultrahydrophobic Polymeric Surfaces Prepared Using Plasma Chemistry” Hsieh, M.C.; Youngblood, J.P.; Chen, W.; McCarthy, T.J. Polymer Surface Modification: Relevance to Adhesion, Volume 2 Mittal, K.L. (Ed.) 2000, 77-89.
“Ultrahydrophobic Polymer Surfaces Prepared by Simultaneous Ablation of Polypropylene and Sputtering of Poly(tetrafluoroethylene) Using Radio Frequency Plasma” Youngblood, J.P.; McCarthy, T.J. Macromolecules 1999, 20, 6800.
“Ultrahydrophobic and Ultralyophobic Surfaces – Some Comments and Some Examples” Chen, W.; Fadeev, A.Y.; Hsieh, M.C.; Oner, D.; Youngblood, J.P.; McCarthy, T.J. Langmuir 1999, 10, 3395.
"Self-Cleaning Anti-Fog Materials," Youngblood, J. P.; Sellenet, P. H. Provisional Patent Application by Brinks, Hofer, Gilson, and Lione (Yuezhong Feng, agent).
"Hydrophilized Bactericidal Polymers," Youngblood, J. P.; Sellenet, P. H. United States Patent Application 20070048249 by Brinks, Hofer, Gilson, and Lione (Peter Brunovskis, agent), 2007.