Control Nanoparticle Patterning via Asymmetric Functionalization

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National Science Foundation - Division of Chemical &Transport Systems Particulate & Multiphase Processes Program (1415)Proposal Number: 0730738 Principal Investigators: Li, Christopher Affiliation: Drexel University Proposal Title: Control Nanoparticle Patterning via Asymmetric Functionalization Intellectual Merit. Assembling nanoparticles (NPs) into desired patterns is one of the major hurdles to bringing these fascinating materials into many practical applications. Synthesizing tailor-made, asymmetrically functionalized NPs (AFNPs) holds the key to overcoming this hurdle. We recently developed a polymer-single-crystal-templating method to synthesize AFNPs. Polymer single crystals with functional groups on the crystal surface were used to functionalize NPs. The solid state nature of these crystals renders the asymmetric functionalization. In the proposed research, we aim to further explore this method to synthesize a variety of AFNPs and assemble them into various structures for different applications. The specific objectives are: 1) to synthesize a variety of well-controlled AFNPs with different optical and electronic properties. A number of carefully selected functional groups (including -OH,-COOH, NH2 and different polymers) will be coupled with these AFNPs. NP-containing triblock copolymers will also be synthesized. Special efforts will be devoted to synthesizing monofunctionalized NPs where only one polymer chain is attached to the NP. 2) to assemble the above tailor-made AFNPs into various structures. The AFNPs can be regarded as artificial atoms. By using ligands with proper functional groups, they can selectively bond with others and form a cluster (artificial molecule). NP dimers, H2O-shaped clusters and NP chains containing one or two types of NPs will be synthesized. Self-assembly of the NP-containing triblock copolymers will also be investigated. Nanostructures such as ABCCBA lamellar and core-shell cylinder could be formed by carefully tuning the triblock copolymer structures. The approach method is a generic way to achieve a variety of AFNPs. Compared to the state-of-the-art in the AFNP field, the key advantage of our proposed research is using polymer single crystals as the solid substrate for coupling reaction. The benefits of using this unique substrate can be summarized as the follows. (1) The polymer single crystal provides a reversible substrate for AFNP synthesis; multifunctionality is also feasible; (2) Free standing mono- or multi-layer NP films can be obtained with controlled NP areal density; (3) Monofunctionalized NPs can also be achieved; (4) A variety of NP complexes such as dimers, H2O-shaped NPs and NP chains (both homo-NP and co-NP chain) can be readily fabricated.Broader Impact. The research aims to tackle a challenging problem in the nanotechnology field. If successful, it could help to bring many fascinating NPs into the market place. The educational component of the proposal includes: (1) Addressing the need for the education of modern developments in polymer nanoscience and nanotechnology by developing "Nanohybrid Materials" modules which will be used in the "Nanostructured Polymeric Materials" course. (2) Involving high school students and teachers, particularly under-represented populations, in the proposed research activities. These proposed educational activities encompass a broad impact. First, the proposed plan will help bridge the existing gap between levels of educational developments by involving high school students and teachers in research activities through a number of mentoring programs. Second, due to the high population of underrepresented groups in the Philadelphia region, the proposed outreach program will be specifically geared towards encouraging the participation of under-represented populations. Third, the proposed research will be publicized through scientific media and public workshops. The dissemination of this information along with hands on experiences for secondary education teachers will result in more informed teachers capable of educating the future by establishing collaborative efforts with school districts in the surrounding Philadelphia region.