NIRT: Nanomolecular Interactions of Novel Biological and Synthetic Polyelectrolyte Brushes

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In this research proposal, an interdisciplinary research team has been assembled that includes 4 PI's representing 5 different academic departments at 3 universities who have expertise in a broad complementary array of fields of science and engineering. The overall goal of this research prrposal is to use powerful new nanoscale experimental and theoretical tolls and methodologies to deleop a foundation for the fundamental physics of novel technologically important polyelectrolyte (PE) brush and brusk-like systems. One unique aspect of this proposal is the merging of what have historically been largely isolated fields, that of synthetic and biological PE's. The proposal includes 3 specific aims including: 1) nanomechanical and nanostructural investigations of connective tissue polyelectrolytes, II) synthesis and nanoscale interactions of synthetic PE brush gradients and nanoscale objects, and III) a multiscale theoretical approach that will enable bridging the gap of length scales from the atomistic to macroscopic observable quantities using molecular dynamics (MD) simulations both at the atomistic scale and using coarse grained models, molecular theory, and nanoscale continuum Poisson-Boltzmann-based EDL simulations. The model PE systems to be studied are cartilage glycosaminoglycans (Biological) and polyacrylic acid (PAA), poly(dimethylaminoethyl metharylate) (PDMAEMA), and poly(N-isopropyl acrylamide) (PNIPAAm) (synthetic). Polyelectrolytes are technologically important classes of polymers used in a wide variety of applications including: colloidal dispersion stabilization and rheology, environmentally sensitive and stimulus-responsive membranes, drug delivery, and engineered surfaces for control of lubrication and wettability. Despite more than 50 years of continuing interest, the unique properties of charged polymers are still poorly understood, mostly due to the fact that up until recently, experimental and theoretical methods needed to study such systems directly at the nanoscale in near-physiological environmental conditions did not exist. The proposed research using powerful new nanotechnological techniques will enable the imaging, measurement, and prediction of nanoscale interaction forces within and between model biological and synthetic polyelectrolytes and combined with a novel multiscale theoretical approach will provide fundamental understanding of such systems. The results will be important for future understanding of cartilage, its strength, and its fundamental mechanical and chemical properties. Educational and outreach activities include coordination with K-12 teachers in developing demonstration modules, interaction with K-12 students and teachers, and incorporation of undergraduate students as researchers in the project.