This particular project is aimed at the development of novel manufacturing techniques for fabrication and surface functionalization of arrays/forests of high-aspect-ratio composite magnetic nanofibers (nanowires) with variable (optimized) density. These materials promise numerous micro and nanofluidic applications involving the transport of liquids, suspensions and particles, microfluidic agitation and mixing, alternation of wetting and adhesion. As a strategic goal of this proposal we envision the assembling of hybrid magnetic nanofibers into ordered nanostructures by combination of: (a) Template method for nanofiber fabrication, (b) Colloidal lithography for regulation of nanofiber density in the forest, and (c) Surface functionalization of nanofibers to achieve controlled interactions with the surrounding environment. The uniqueness of the materials to be developed is revealed in that the nanofibers should have a core-sheath morphology with a flexible magnetic metallic core and an organic sheath, and also in that the density of the nanofibers in the arrays is optimized. Development of the proposed approach will directly impact the implementation of recent advances in nanoscience and nanotechnology to industrial technologies with broad applications, including analytical chemistry, medicine, bionanotechnology, optics. Another priority of the proposed project is the involvement of the brightest high school, undergraduate and graduate students in modern nanotechnology oriented research. The project will result in the training of these students in the areas of nanofabrication and various micro- and nanoelectromechanical systems, and surface science. Students will greatly benefit from the interdisciplinary nature of this project. Significant effort will be directed toward increasing the numbers of students--especially minorities and women--who are pursuing advanced degrees in science and engineering.
Major Outcome: Researchers at Clarkson and Clemson Universities have successfully engineered liquid-repellent coatings which repel all major organic liquids and water-born solutions (superomniphobic behavior). The coatings can be switched from omniphobic to omniphilic in an external magnetic field. Impact/benefits: Superomniphobic surfaces could find applications for a uniform cloth that protects from chemical and biological weapons, smudge-free screens and antimicrobial paints. Tuning wetting behavior with magnetic fields finds promising applications for miniaturized optical and microfluidic devices. Background/Explanation: There no commercially available superomniphobic materials. Only a few examples of laboratory experiments with such materials have been reported in literature. There are no commercial and laboratory examples of coatings when wetting is switched in a magnetic field. The new coatings developed by the Clemson and Clarkson researchers demonstrate superomniphobic wetting behavior and at the same time the wetting behavior can be switched in magnetic field. The superomniphobic behavior is achieved via specially engineered texture of the coatings which are made of Ni micronails. The dimensions and surface functionalization of the microtextured nail-like structure is optimized to repel all liquids including aqueous solutions, nonpolar, polar organic liquids, and a model chemical, that is used to mimic wetting behavior of chemical weapons – tributyl phosphate. The liquid-repellent properties originate from the capillary forces acting upward and pushing liquid away from the coating. The effect of the capillary forces is due to the overhang structure of the nail-like texture. Magnetic properties of the Ni micronails are used to bend them in a magnetic field and change the overhang angle. The latter results in changes of the direction of capillary forces and switch the coatings from non-wetting to wetting regime. Scientific Uniqueness: The best previously reported omniphobic surfaces repelled alkanes and some alcohols. No such universal nonwetting was demonstrated before, specifically for amphiphilic liquids like a tributyl phosphate (a common model for chemical threats). The developed coating with magnetic switching of wetting has been unavailable previously. The developed novel coatings have promising applications in engineering, defense, medicine,optics and biosensors. Intellectual merit of this project is related to the development of the mictrotextured coatings using the template method. The coatings have superomniphobic properties that can be changed in magnetic field. The templates, electrodeposition of Ni into the templates, dimensions and the surfaces functionalization were developed and optimized to achieve the target properties of the material. In terms of Broader Impacts, this work is notable because the obtained results are expected to have substantial impact on the development of new technologies, functional materials and devices. The project has an important educational role for training undergraduate, graduate students and ostdoctoral researchers. The project helped for strengthening of the training of students in the areas of microfabrication, surface science,electrochemistry, and materials science and engineering. The project provided opportunities to integrate research and education through cross-disciplinary student training in research labs, and scientific seminars. The PIs involved both undergraduate and graduate students in the research and train them to gain (i) expertise in microfabrication techniques, (ii) familiarity with modern concepts in materials and surface chemistry, (iii) the ability to synthesize and characterize functional materials, (iv) the ability to run experiments, gather data, and make discoveries, and (v) the ability to write scientific papers and make effective technical presentations. The project helped to strengthen collaboration between Clarkson University (NY) and Clemson University (SC) and develops partnerships between faculty and students.
