Abstract:

This dataset contains estimates of the mutual diffusion coefficient and hydrodynamic radius of polymer-modified silica nanoparticles determined via light scatter characteristics. Seven species of poly(caprolactone) (PCL) and hyperbranched poly(glycidol) (HPG) modified nanoparticles were exposed to laboratory-weathered oil collected from the leaking Deepwater Horizon well. Dynamic light scattering (DLS) analysis measured the fluctuations in the scattering intensity of the samples, analyzed by the intensity autocorrelation function. The slope of the plot of the decay rate of the autocorrelation function versus the square of the scalar magnitude of the scattering vector yields the mutual diffusion coefficient. The estimate of the diffusion is then used to calculate the hydrodynamic size using the Stokes-Einstein relation.

Suggested Citation:

Savin, Daniel; Walley, Susan. 2020. Laboratory measurements of light scattering data for polymer-modified nanoparticles to determine diffusion coefficient and hydrodynamic radius. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-v8ty-qt97

Purpose:

The determination of size changes when polymer-modified nanoparticles are exposed to oil.

Data Parameters and Units:

Correlation function decay rate [Gamma, 1/s], square of light scattering vector [q^2, 1/m^2], mutual diffusion coefficient [D_m, m^2/s], hydrodynamic radius [Rh, nm], viscosity of water [eta, centipoise or mPa s].

Methods:

All seven polymer-modified silica nanoparticle species [SiO2-HPG, SiO2-HPG-PCL, SiO2-HPG-PCL-HPG, SiO2-HPG (no. 151201), SiO2-5PCL-PEG, SiO2-2PCL-PEG, and SiO2-PCL-PEGMAOM] were analyzed at 1% by weight particle concentration. The nanoparticles were exposed to a weathered oil solution. The oil, provided by AECOM Environment Toxicology Laboratory, was collected from the leaking Deepwater Horizon well. A mixture of 1 ml of oil in 1 L of 20% Hanks Balanced Salt Solution was weathered for one week by mechanical mixing of the solution in a laboratory hood. On day 7, the aqueous phase was separated from the oil using a separation funnel. The water associated fraction (WAF) was spiked with a stock solution of nanoparticles. To keep particles suspended, each concentration of exposure solution was aerated, forcing the movement of liquid inside the exposure beakers. Dynamic light scattering (DLS) analysis was performed on an ALV/CG5-3 four-angle, compact goniometer system (Langen, Germany), which consisted of a 35 mW HeNe linear polarized laser operating at a wavelength of 632.8 nm. Fluctuations in the scattering intensity were measured via an ALV/LSE-50004 multiple tau digital correlator. Decay rates, Γ, were obtained by fitting single-exponential functions to the intensity autocorrelation function using a second-order cumulant analysis. A plot of Γ vs. the square of the light scattering angle vector, q, yields the mutual diffusion coefficient, D_m.

Instruments:

ALV/CG5-3 four-angle, compact goniometer system (Langen, Germany), ALV/LSE-50004 multiple tau digital correlator.

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