Dr. Jeffrey P. YoungbloodThe MIT Technology Review article Self-Cleaning, Fog-Free Windshields said
A new adaptive polymer coating combines unusual chemical properties to help maintain a clear view.
A new coating that changes its structure depending on whether it’s in contact with oil or water could prevent windshields from fogging up or accumulating oily deposits. The coating was developed at Purdue University and reported at last week’s American Chemical Society meeting.
Drop water on a surface treated with the coating, and it rapidly spreads out, creating a thin film. This action prevents the formation of the tiny water droplets that make up fog. Add oil, however, and the surface responds the opposite way, repelling oil and causing it to bead up. Any oil that doesn’t run off on its own would be easily wiped away with water, making it unnecessary for a driver to use soap.
The coating could be particularly useful on the inside of car windshields, says Jeffrey Youngblood, the professor of materials engineering at Purdue who led the work. Trace amounts of oil, such as from protective treatments on the interior surfaces in a car, cling to glass, changing the surface energy of the glass and increasing its tendency to fog. The coating would both repel the oil and prevent the water droplets of fog from forming. The coating’s properties could also make it useful in filters. Applied to a porous silica, it allows water to pass through but raises barriers to oil. This could be useful for cleaning up oil spills.
Jeffrey P. Youngblood, Ph.D. is
Assistant Professor of Materials Engineering,
School of Materials Engineering,
Neil Armstrong Hall of Engineering, Purdue University.
His 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.
His projects include:
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 he has 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. His 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.
His 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 his 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
He is 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 he has 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, he has optimized and characterized the deposition kinetics of various systems of organo-silanes.
His 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.
Jeffrey coauthored Optimization of Silica Silanization by 3-Aminopropyltriethoxysilane, Ultrahydrophobic Polymer Surfaces Prepared by Simultaneous Ablation of Polypropylene and Sputtering of Poly(tetrafluoroethylene) Using Radio Frequency Plasma, Coatings based on side-chain ether-linked poly(ethylene glycol) and fluorocarbon polymers for the control of marine biofouling, Synergistic Activity of Hydrophilic Modification in Antibiotic Polymers, Ultrahydrophobic and Ultralyophobic Surfaces: Some Comments and Examples, and Self-Cleaning and Anti-Fog Surfaces via Stimuli-Responsive Polymer Brushes.
Jeffrey earned his B.S. in Chemistry and Physics at Louisiana State University in 1996, his Ph.D. in Polymer Science and Engineering at the University of Massachusetts in 2001, and was a Postdoctoral Associate from 2001 to 2003 in Materials Science and Engineering at Cornell University. He holds the patent Hydrophilized bactericidal polymers.