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Novel Polymer Microgel Dispersions with an Inverse Thermo-reversible Gelation

Novel Polymer Microgel Dispersions with an Inverse Thermo-reversible Gelation Zhibing Hu, University of North Texas, DMR-0507208.

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Novel Polymer Microgel Dispersions with an Inverse Thermo-reversible Gelation

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  1. Novel Polymer Microgel Dispersions with an Inverse Thermo-reversible Gelation Zhibing Hu, University of North Texas, DMR-0507208 An aqueous suspension of polymer microgels has been synthesized. It is a fluid at room temperature but becomes a gel above 33 oC. These microgels consist of polymer interpenetrating networks (IPN) of poly-N-isopropylacrylamide (PNIPAM) and polyacrylic acid (PAAc) and can form a reversible physical link between neighboring particles. We have installed an advanced rheometer (VISCOANALYSER, ATS RheoSystems/Reologica Instruments) in our lab and are studying viscoelastic properties of this suspension. The right figure shows typical temperature dependence of elastic modulus of this suspension. Using this suspension as a model system, we will enhance our understanding on gelation and jamming processes. Temperature dependence of elastic modulus of the aqueous suspension of PNIPAM-PAAc IPN microgels with polymer concentration about 3.8 wt %. The sharp increase of G’ and G’’ near 33 oC indicates gelation of the suspension.

  2. Novel Polymer Microgel Dispersions with an Inverse Thermoreversible Gelation Zhibing Hu, University of North Texas, DMR-0507208 • Education: • Two graduate students have worked on this project. • Stephen Crouch successfully defended his M. Sc. thesis entitled “The synthesis and study of poly(N-Isopropylacrylamide)/poly(acrylic acid) interpenetrating polymer network nanoparticle hydrogels” in May 2006. • Nicole Fox, an undergraduate student, and William Estabrook, an undergraduate student sponsored by NSF’s REU program, have worked on assemblies of polymer microgels. They presented their results at the 2005 Fall Texas Section Meeting of the American Physical Society at the University of Houston. They both received the Outstanding Student Presentation Award at the meeting. • One student of the Texas Science and Mathematic Academy (TAMS) at UNT has participated in this project. • Outreach: • The PI has made physics demonstrations for undergraduate students, pre-college teachers, young people, and other members of the public.

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