Tunable Nanoparticle Stability in Concentrated Polymer Solutions On the Basis of the Temperature Dependent Solvent Quality

Abstract

The ability to control the degree of particle dispersion in polymer solutions has been a long-standing subject in colloidal science. While a generally accepted principle is that nonadsorbing polymers can induce depletion attraction, which is mostly temperature independent, the effects of adding adsorbing polymers are still poorly understood. In this study, we investigated the effects of adsorbing polymers on the temperature-dependent stability of nanoparticles. The model systems consisted of silica nanoparticles in low-molecularweight poly(ethylene glycol) solutions. The detailed microstructures were determined with small-angle X-ray and neutron scattering measurements, while the dynamics of the temperature-dependent microstructures of the nanoparticles and polymers were probed with diffusing-wave spectroscopy. It was found that a poor solvent for polymer could drive adsorbed polymers to leave the particle substrate and return to the bulk solution due to a complicated interaction with surface, while the loss of the steric layer causes the nanoparticles to aggregate at elevated temperatures.

Aggregation-Driven Controllable Plasmonic Transition of Silica-Coated Gold Nanoparticles with Temperature-Dependent Polymer–Nanoparticle Interactions for Potential Applications in Optoelectronic Devices

“…Thus, we hypothesized that the substantial change of particle interaction arises from the polymer-induced interactions. We previously studied the stability of silica NPs in PEG 400 solutions with varying temperature . On the basis of the similarity between the previous and present studies, we hypothesized that the strong temperature-dependent polymer adsorption causes the stability of Au@SiO 2 NPs.…”

“…The reported temperature dependent- aggregation is expected to be found at other temperatures as the solvent quality/polymer adsorption decreases with temperatures. In the similar systems, silica nanoparticles can be stable up to 40 °C, but aggregated at 60 °C. ,, The Au@SiO 2 NPs can be aggregated at temperatures below 70 °C; however, the rate of aggregation is expected to be slower. Thus, we chose 70 °C to observe the dynamic aggregation and its LSPR effect within a certain amount of time.…”

“…In the similar systems, silica nanoparticles can be stable up to 40 °C, but aggregated at 60 °C. 48,51,52 The Au@SiO 2 NPs can be aggregated at temperatures below 70 °C; however, the rate of aggregation is expected to be slower. Thus, we chose 70 °C to observe the dynamic aggregation and its LSPR effect within a certain amount of time.…”

Structural Development of Nanoparticle Dispersion during Drying in Polymer Nanocomposite Films

“…Controlling NP dispersions in polymer matrices is one of the most actively studied subjects in the field of polymer/colloid science and relevant industries. − A well-known methodology to obtain a desired state of NP dispersion in polymer nanocomposites is to control the interparticle interaction. One possible route for this is to select a suitable solvent character or quality to tune the physicochemical affinity between the particle surface and the hosting polymer.…”

Enhanced Mechanical Properties of Polymer Nanocomposites Using Dopamine-Modified Polymers at Nanoparticle Surfaces in Very Low Molecular Weight Polymers

“…At ϕ c = 0.17, NPs without DOPA-mPEG were well-dispersed without aggregation showing the first order peak at qD ∼ 4.5. As r σ increases, particles were gradually less ordered and aggregated, as indicated by the peak disappearance and upturns at low qD . − …”