1 research outputs found
Synergistic Role of Temperature and Salinity in Aggregation of Nonionic Surfactant-Coated Silica Nanoparticles
The adsorption of nonionic surfactants onto hydrophilic
nanoparticles
(NPs) is anticipated to increase their stability in aqueous medium.
While nonionic surfactants show salinity- and temperature-dependent
bulk phase behavior in water, the effects of these two solvent parameters
on surfactant adsorption and self-assembly onto NPs are poorly understood.
In this study, we combine adsorption isotherms, dispersion transmittance,
and small-angle neutron scattering (SANS) to investigate the effects
of salinity and temperature on the adsorption of pentaethylene glycol
monododecyl ether (C12E5) surfactant on silica
NPs. We find an increase in the amount of surfactant adsorbed onto
the NPs with increasing temperature and salinity. Based on SANS measurements
and corresponding analysis using computational reverse-engineering
analysis of scattering experiments (CREASE), we show that the increase
in salinity and temperature results in the aggregation of silica NPs.
We further demonstrate the non-monotonic changes in viscosity for
the C12E5–silica NP mixture with increasing
temperature and salinity and correlate the observations to the aggregated
state of NPs. The study provides a fundamental understanding of the
configuration and phase transition of the surfactant-coated NPs and
presents a strategy to manipulate the viscosity of such dispersion
using temperature as a stimulus