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Diffusion of deuterated polystyrene(dPS) is probed in PS matricescontaining stringlike chained nanoparticles (cNP) grafted with PS.This investigation connects prior diffusion studies in model sphericaland cylindrical NP systems and provides insight for technologicalapplications, which typically involve irregularly shaped NPs suchas carbon black. We report that the presence of chained NPs in PSmatrices induces a minimum in the diffusion coefficient (D) with increasing cNP concentration when the key length scale, 2Rg/L≤ 1.5, where Rgis the gyration radius of dPS and Lis the mean length of the impenetrable core of the chainedNPs. When 2Rg/L>1.5, Ddecreases monotonically as the NP concentrationincreases.Note that in all cases 2Rgis larger thanthe diameter of these short-stringy NPs. The diffusion minimum isattributed to anisotropic diffusion in the vicinity of the chainedNPs and requires that the long dimension of the cNP be comparableto or longer than the tracer molecule. Two normalizations are exploredto provide insight about the diffusion mechanism: D/D0where D0is the diffusion coefficient in a pure homopolymer matrix and D/Dewhere Deis an effective diffusion coefficient that accountsfor the distinct dynamics in the PS matrix and PS brush regions. For D/D0, a sharp transition froma diffusion minimum to a monotonic decrease is observed as dPS molecularweight increases, while for D/Dethe transition is more gradual. These studies show not onlythat the NPs act as impenetrable obstacles for polymer diffusion butthat the polymer brush grafted to the cNP provides an alternativepathway to control polymer dynamics. [ABSTRACT FROM AUTHOR]

Polymer-melt-based manufacturing processes for nanostructures offer high-rate, environmentally friendly, and commercially viable alternatives to solution-based methods. In this work, electrophoresis of a model carbon black and polystyrene system with moderate viscosity was used to investigate the viability of adapting nanoassembly processes to the high viscosity environment of polymer melts. The presence of polystyrene did not prevent deposition of carbon black, but deposition rates decreased at shorter deposition times; deposition was not linear with increasing applied voltage; and greater solution concentrations reduced the critical voltages (i.e., the voltage at which the rate of deposition changed). X-ray photoelectron spectroscopy (XPS) results and comparison of experimental data with Hamaker’s model showed that about 1.6% of the available polystyrene was initially deposited with the carbon black. At voltages above the critical voltage, the deposited mass was less than the Hamaker prediction, indicating the formation of electrically insulating layers on the electrodes. The overall behavior suggests that polymer melt-based processes could be employed for high-rate fabrication of nano-optical devices, biochemical sensors, and nanoelectronics. [ABSTRACT FROM AUTHOR]