Russell Gorga PhD

This proposal seeks to understand the fundamental science underlying electrospinning from an unconfined sheet of molten polymer. This method is "green" (solvent-free and compatible with recyclable plastics), should result in meso-fibers having dramatically improved mechanical properties, and will allow manipulation of the electrospinning process to create smaller fiber diameters than typically achievable under traditional needle-based approaches. The work will involve unconfined melt electrospinning of the three common commercial thermoplastics: polyethylene, polypropylene and polyethylene terephthalate. The research focuses on the roles of flow rate and melt conductivity, which have not been previously explored due to severe experimental challenges. Conductivity will be altered by adding conductive compounds (Aim 1) or by generating a localized electrical discharge within or near the fluid (Aim 2).

Working dogs play an integral role in the day to day operations of both military soldiers and law enforcement officers worldwide. All canine handlers and trainers use protective bite sleeves for engagement and apprehension training. However, the canine bite sleeves on the market today fail to measure the bite force of the working dog. The result is that trainers must rely on years of training experience to subjectively evaluate their canines which may result in ineffective training, canine/handler injury or unsafe environments during operations. The development of the canine bite force sleeve would help provide an objective measurement tool for trainers to more thoroughly understand canine bite dynamics. The objective of the project is to re-design a commercial bite sleeve by incorporating electronic (or other) pressure sensors within the sleeve that accurately measures, records, and displays bite force data in real time. Canine bite profile includes overall bite pressure, mapping the bite print and duration of a bite.

The ability to controllably trigger breaking of chemical bonds is a crucial step in reducing environment waste and pollution due to plastics. Discarded plastic material often detrimentally resides within the environment for many years, leading to myriad problems: sickening or killing a wide range of life forms from microbes to large animals, effecting both marine and terrestrial mammals and birds, clogging drainage and water processing systems, contaminating landfills with deleterious chemicals, or resulting in sterile soil and accumulation of toxins within specific ecosystems. A key issue underlying the ability intentionally initiate degradation of polymeric materials is implementing an approach to start breaking of chemical bonds - enabling a substance that has robust material properties during use, which can then be re-worked or deteriorated upon command. Proving this proposal’s hypothesis that degradation (i.e., bond-breaking) could be controllably triggered and/or driven via photothermal heating would result in a powerful tool that addresses this complex problem on multiple-levels: for instance, providing an opportunity for one-time treatment to begin a long degradation process (a consumer shines a green light on a plastic object upon discarding), generating visible light sensitivity that would enhance deterioration using sunlight, or resulting in thermally triggered re-workable adhesives/epoxies. The success of even a single proposed modality would have a significant effect in mediating plastic environmental pollution. This proposal tests the hypothesis that the strongly inhomogeneous temperature gradients created in the interior of polymers upon photothermal heating of embedded nanoparticles can be utilized to efficiently trigger thermally-induced bond breaking in polymeric materials via exposure to near infrared or visible light. Such heat generated within the material can impel a degrading or cross-link-breaking chemical reaction either by instigating a self-sustaining process, or when applied over a longer time by continuously enhancing such reaction rates. Thus, the materials developed due to this scientific knowledge would have an additional functionality -- the ability to degrade upon command. Previous work has shown that the inhomogeneous temperature profile created within polymers undergoing photothermal heating, which creates intense local heat at isolated nanoparticle locations embedded within the sample, results in a very different material response (for instance, far more rapid crystallization rates) than when utilizing conventional heating methods, where the entire sample is slowly, uniformly warmed from the outside to the inside. This internal placement of nanoscale heaters leads to triggering of chemical reaction fronts that spread outwards and natural segregating of the material into smaller pieces. Rather than degrading from the surface inwards, which always retains an intact inner core of material, here the material is homogeneously fragmented from within and the chemistry reactions occur from the inside outward.

A working canine must undergo physiological stress, which should be monitored to keep track of the canine’s health and safety. Our team will develop a textile enclosed electronic device for canines that is capable of detecting and quantifying stress levels. The device will be comprised of readily available electronic components and must include a comfortable textile that can be mounted on an animal, without a further increase of the canine’s stress level. This project will work in conjunction with the Senior Design Capstone course in Textile Engineering & Textile Technology during the 2015-2016 academic year. A final product and report will be delivered to the sponsoring agency by June 15th, 2016. The team will work in conjunction with the Army Research Office and K2 Solutions.

The purpose of this project is to provide academic subject matter expertise and direct research and technical support for United States Army Special Operations Command ( USASOC). The intent of this project is to make technical knowledge, data and forward-looking solutions available to USASOC. The scope of the project may cover a wide range of topic areas to include, but not be limited to: materials science, chemistry, life sciences, human performance, computing science, network science, mechanical sciences, electronics and engineering across multiple core disciplines. In this project, senior design teams will develop a bite suit that mimics the tactile sensation, puncture resistance, smell, and taste of skin for military working dog-combat canine bite training. A realistic bite suit with artificial skin and embedded sensors that will enable measurement of bite pressure and release will be developed. The team will fabricate a proof-of-concept prototype at the end of the design course for delivery to USASOC.

We will investigate the use of the photothermal effect of metal nanoparticles as a tool for materials processing and actuation. This effect converts light energy into heat via coupling with the nanoparticle surface plasmon resonance; thus, metal nanoparticles can act as externally-driven, nano-sized thermal sources from within a material, providing efficient, selective, and remotely-controlled localized heating when the material (doped with a small fraction of nanoparticles) is irradiated with relatively weak light. Our previous research has recently demonstrated that using relatively weak irradiation intensity, nanofibrous mats with a low concentration of metal nanoparticles can be facilely heated to temperatures sufficient to melt the polymer matrix; this effect can also be usefully employed in bulk materials. Such efficient and controllable localized heating represents a powerful new tool for in situ processing and actuation. Instead of requiring development of specific light-sensitive polymeric materials, any material that can be thermally processed, activated, or actuated could now be controlled in-situ by a light field. The spatial and wavelength specificity of the heating offers several implicit advantages: 1) Heat is generated from within a medium, as opposed to conventional methods where the surface of the material is the first to warm; thus, for instance, the interior of a structure could be processed to a higher temperature than the surface. 2) Heat is generated only in the immediate region of the nanoparticles; thus by placing nanoparticles in particular regions of the sample, selective in situ processing can be accomplished. 3) The heat-generating illumination source can be optimally tuned for the given system; as the nanoparticle absorption wavelength is characteristic of the particle type, one can select a particle resonant with a preferred wavelength in order to obtain maximum light penetration into a particular material. 4) Different nanoparticle heater types (resonant at different light frequencies) can be incorporated into different regions of the same sample allowing heating of different regions at will. We will address three specific aims: 1) To develop techniques to measure temperature at the nanometer-size scale in order to experimentally determine the maximum temperature and the temperature gradient within the medium. Towards this activity we have utilized distinct, temperature-dependent changes in the emission spectrum of fluorophores such that they act as remote-readout nanoscale thermometers. 2) To utilize metal nanoparticles to actuate shape-memory polymers and explore multistage shape memory schemes. 3) To develop hybrid nanofiber materials (core-sheath structures with thermoset-precursor cores) that are flexible when fabricated and can be positioned, deformed, or templated on a three-dimensional structure and subsequently "stiffened" from within, dramatically increasing their modulus, by photothermal curing of the thermoset core to form a rigid assembly.

Currently, there is limited process chemistry for converting lignin to profitable advanced materials. The results of this proposal will establish the reaction parameters and surface chemistry modifications necessary for shifting the paradigm of low-profit lignin products to the utilization of lignin in high value, energy-related applications. A rich interplay between the forest biomaterials and silicon chemistry communities will be established through a fundamentally different surface modification of lignin with silicon-containing precursors. The results are expected to impart thermal stability and surface-activity enhancement to lignin macromolecules. If successful, this work will provide biorefineries in the Southeastern Sun Grant region with processing options for deriving increased value from lignocellulosic biomass. More broadly, providing value-added applications for bio-derived materials can reduce our dependence on fossil fuels, increase rural income and help to solve environmental issues caused by the use of non-renewable resources. This proposal seeks to address the USDA-NIFA and the SGP-SER priority areas of improving preprocessing for high quality feedstock from biomass from switchgrass (primary) and pine. Specific to this proposal is the development of high value-added ceramic-carbon hybrid fiber. While lignin is the second most abundant polymer found in nature, its complex chemical structure and poor thermal stability limit its application-use to low-profit fillers and adhesives. Our central hypothesis is that lignin?s limitations in higher cost margin materials can be reduced with surface modification by thermally stable silicon-containing precursors which impart unique surface properties.

The objective of this research is looking at the existing materials which can be used as solar textiles and also developing the new materials which can be used in automotive seating and can harvest the solar energy and store it. This will include a thorough research of current technologies and existing materials and the development of a prototype that can capture the solar energy and store the energy.

This fundamental research will enable the production of nanofibrous substrates for use in a wide-range of applications, such as filtration, sensors, fuel cells, and tissue engineering. Our approach is to make a paradigm shift from fiber growth from a droplet suspended from a needle to fiber growth from a large concentration of droplets on a surface. Such a surface can easily be patterned to provide literally thousands or tens of thousands (25 million sites for a 10 um square "patch" of hydrophobic/hydrophillic material on a 0.1 m square plate) of possible spinning sites. The ability to efficiently and continuously supply these "spinning sites" with solution, to determine where spinning originates, and to control droplet and fiber size are primary objectives of this research. We propose that much smaller diameter fibers (~ 50 nm or less) can be obtained by controlled design of the charged plate (where key parameters include interfacial tension and surface architecture). Morphology, mechanical, and electrical properties will be studied to develop a mechanistic understanding of the processing-property relationships as the primary fundamental outcome.

The goal of this proposal is to create films and fibers loaded with high percentages of radiopaque and/or high atomic number fillers that will attenuate radiation. Data will be generated on radiation attenuation of films and fibers to demonstrate the performance of such systems.