Enhanced Colloidal Stabilization via Adsorption of Diblock Copolymer from a Nonselective ϑ Solvent

Abstract

Experimental measurements, interpreted with mean field theories, provide quantitative understanding of the stability of colloidal particles coated with a highly asymmetric diblock copolymer. Adsorption of poly((dimethylamino)ethyl methacrylate)/poly(n-butyl methacrylate) onto colloidal silica particles from 2-propanol, which is nonselective and a ϑ solvent for poly(n-butyl methacrylate), yields a very high surface coverage and a highly stretched brush. With increasing temperature, the adsorbed chains swell more than those in the bulk. Upon cooling, the dispersions exhibit thermodynamic stability well below the ϑ temperature of the nonadsorbed block. A simple mean-field theory rationalizes the stability as a consequence of the high surface coverage, which is attributed in turn to strong segmental adsorption of the short anchor block and negligible excluded volume interactions among the stabilizing chains.

Ionic Strength and Curvature Effects in Flat and Highly Curved Polyelectrolyte Brushes

“…Two comments are in order here. First, a similar difference in sensitivity between tethered polymer chains and those in the bulk was observed 50 for diblock copolymers of poly((dimethylamino)ethyl methacrylate)/ poly(n-butyl methacrylate) adsorbed on colloidal silica from a nonselective solvent. Second, the evident relationship between core radius and sensitivity to added salt is an oversimplification, since the surface density is not held constant (Table 5).…”

Adsorption of Polyetheramines on Montmorillonite at High pH

“…To investigate the effect of solvent quality on adsorption, temperature and salt concentration were varied. This approach was chosen following Hariharan and Russel, who investigated the adsorption of poly((dimethylamino)ethylmethacrylate)/poly( n -butylmethacrylate) onto silica particles and found the adsorbed amount is higher in θ solvent than in good solvent. Experiments at room temperature and 90 °C show similar adsorbed amounts and released ion concentrations.…”

Adsorption and Polymer Film Formation on Metal Nanoclusters

“…Experimental Data Analysis. The thickness of the polymer capping layer can be calculated using a combination of transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA) experimental methods. , The first step in the determination of polymer layer thickness using the TGA experimental results is to calculate the average number of cobalt clusters present in the sample, N C . This can be done as follows: where ε is the volume fraction of the cobalt atoms in the cluster, m sample is the mass of the sample placed in the TGA pan, and w Co is the mass fraction of the cobalt moiety after the decomposition of the polymer.…”

“…The thickness of the polymer capping layer can be calculated using a combination of transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA) experimental methods. 33,34 The first step in the determination of polymer layer thickness using the TGA experimental results is to calculate the average number of cobalt clusters present in the sample, N C . This can be done as follows:…”