The objective of this research is to establish a knowledge base for a precision solid freeform fabrication process that creates polymer matrix nanocomposites that are fully functional as gradient refractive index lenses. Such lenses are flat rather than spherical. The project will seek to determine the principles behind forming gradient composites by inkjet deposition, and photocuring layer-by-layer from optically clear, photosensitized thermoset resins, which contain various amounts of well-dispersed nano-sized ceramic particles. The work will include selecting and combining the most appropriate polymer and ceramic nanoparticle components as well as determining the optimum conditions for inkjet processing and curing. It will also integrate the use of an optics design model in conjunction with the inkjet process. The design output then will be coupled with the printer driver. This is necessary for the fabrication of layers that have concentrations of particles in different locations in order to create the required refractive index gradients.
If successful, the research has the potential for ushering in an economical new type of flexible optic manufacturing. It will provide a platform for direct production of optics ranging from one-of-a-kind prototypes to full production runs without the need for grinding or polishing. Polymeric gradient lenses can be used in lens systems to reduce the number of elements by 25 to 50% with significant weight reductions. Since they will be more accurate, they also can be used to relax optical designs, lowering the sensitivity to alignment and fabrication errors. The combination of custom capability and cost-effectiveness may result in a sizeable market for this process. Moreover, the concepts developed in this program will be applicable to fabricating other nanocomposite systems, particularly structural composites reinforced with clays and carbon nanofibers. Using the same methodology with more robust matrix resin systems, such as aerospace epoxies, it should be possible to fabricate functional advanced nano-composites with enhanced modulus, strength and toughness characteristics.
(SFF) has been developed. The process involves ink-jet deposition (IJD) and incorporates inorganic nanoparticles into a low viscosity matrix resin that is easy to process. The resin rapidly photocures under UV light exposure to produce viable, functionally graded polymer composite parts by building them layer by layer. One of the applications is to produce ceramic particle filled composites that are fully functional optical components that form gradient refractive index lenses (GRIN). Other optical applications include filters, reflectors, optical waveguides, optical adhesives, and antireflection films. Intellectual merit of the Project: GRIN lenses are flat rather than spherical and focus light by variation in refractive index, rather than shape. The presence of the nanoparticles in different concentrations creates the variations in refractive index necessary to form the optical gradients. Inkjet printing is a valuable technology for forming nano-composites that have precisely controlled variations in composition. Incorporating inorganic domains into a polymer matrix is an effective way to fabricate high refractive index composite materials. However, the size of the inorganic domains must be less than one tenth of the wavelength of visible light (400-800 nm) in order to avoid light scattering and obtain transparent polymer composites. So dispersing the particles and controlling the size of inorganic domains in the nanometer regime is extremely important and it is also quite a challenging task. In this project we developed effective chemical methods for dispersing the nanoparticles in the composites Inkjet deposition for forming polymer matrix nano-composites has several advantages. It allows us to deposit the appropriate compositions at different locations for forming optical materials that have the exact specifications for GRIN applications. It is a high-resolution method, which is precise and reproducible. Thus the method is an ideal technique for creating the spatial material distributions required for designing computer optimized custom made GRIN lenses and optical components. The optical material application is a significant one, which has great commercial potential. GRIN lenses, for example, will be flat, thus eliminating the need for costly grinding or polishing. Also coatings can be applied directly to the GRIN lens during SFF processing eliminating any secondary processing step. There currently is no other fully effective method for forming GRIN optics. Further, spherical surfaced lenses produce images with intrinsic optical aberrations. GRIN lenses eliminate these aberrations. Broader Impacts of the Proposed Effort: From a broader perspective this program will have significant effects and benefits with respect to society and the educational process. There are several important ways that it will benefit technological innovation, the educational process and dissemination of knowledge to the public at large. The results of this program have been used to add sections on nano-composites to courses taught in Materials Engineering at the University of Dayton and in Chemistry and Materials Science at the University of Oregon. In addition the results have been used to add materials on nano-particle and nano-composite characterization to short courses on thermal analysis of polymers and composites that the PI presents for industrial personnel and to a comprehensive book chapter that he has published. Future plans for dissemination of knowledge to the public at large include establishing an internet data base, additional short courses for industry, as well as DVD-ROM and distance learning course offerings. The program also contributed to our laboratory’s infrastructure for research in this area by making it possible to purchase a group of necessary instrumentation, devices, and materials for the project. This included the Dimatix inkjet printer, thermal analysis modules (DMA, TGA), a novel miniature UV LED light source, and a large area UV LED light source. In addition to the primary program on SFF for optical nano-composites it was determined that the technology developed for chemically imparting polymer surface coatings on nanoparticles is also applicable to preparing nanocrystal(NC) quantum dots which are suitable for biomedical imaging applications, especially for cancer cell detection and treatment. To pursue this we formed a biomedical team collaboration with Oregon Health Sciences University (OHSU) and Voxtel Corporation. The biomedical application is to develop a fluorescent nanocrystal probe to image and identify abnormal behavior of important cellular proteins in live cancer cells. With suitab Based on preliminary research,, this nanocrystal approach promises to provide an enhanced level of fluorescence stability and cellular compatibility for diagnostic imaging in situ of tumor cells and tissue. With suitable proteins attached to their surfaces these NCs will seek out cancer cells when injected into a living organism. Based on preliminary studies, this nanocrystal approach promises to provide an enhanced level of fluorescence stability and cellular compatibility for diagnostic imaging in situ of tumor cells and tissue. This in turn will be used to reveal new therapies which are capable of preventing drug-resistant disease relapse and new tumor growth.
