Structure and Dynamics of an active polymer adsorbed on the surface of a cylinder

Structure and dynamics of a driven polymer on a smooth cylindrical surface are studied by Brownian dynamics simulations. The effect of driven force on the polymer adsorption behavior and the...

Influence of Zwitterionic CAPB on Flocculation of the Aqueous Cationic Guar Gum/Glauconite Suspensions at Various pH

The influence of the pseudoamphoteric zwitterionic surfactant cocamidopropylbetaine (CAPB) on the stabilizing flocculating properties of the aqueous suspensions of glauconite (GT) with cationic guar gum (CGG) at various pH values was investigated. The following techniques were used: turbidimetry, UV-VIS spectrophotometry, tensiometry, electrophoretic mobility measurements, SEM, CHN, XRD, and FT-IR. It was established that CGG is an effective glauconite flocculant. Moreover, the most probable mechanism that is responsible for flocculation is bridge flocculation resulting from polymer adsorption on the glauconite surface. The adsorption process is caused by electrostatic interactions between the negatively charged glauconite surface and the positively charged polymer. The amount of CGG adsorption increases with the increase of the pH, which was confirmed by the adsorption and zeta potential measurements. The addition of CAPB increases the amount of the polymer adsorption due to the formation of intermolecular polymer–surfactant complexes; however, it reduces flocculation effectiveness.

Role of Adsorbed Polymers on Nanoparticle Dispersion in Drying Polymer Nanocomposite Films

Polymers adsorbed on nanoparticles (NPs) are important elements that determine the dispersion of NPs in polymer nanocomposite (PNC) films. While previous studies have shown that increasing the number of adsorbed polymers on NPs can improve their dispersion during the drying process, the exact mechanism remained unclear. In this study, we investigated the role of adsorbed polymers in determining the microstructure and dispersion of NPs during the drying process. Investigation of the structural development of NPs using the synchrotron vertical-small-angle X-ray scattering technique revealed that increasing polymer adsorption suppresses bonding between the NPs at later stages of drying, when they approach each other and come in contact. On the particle length scale, NPs with large amounts of adsorbed polymers form loose clusters, whereas those with smaller amounts of adsorbed polymers form dense clusters. On the cluster length scale, loose clusters of NPs with large amounts of adsorbed polymers build densely packed aggregates, while dense clusters of NPs with small amounts of adsorbed polymers become organized into loose aggregates. The potential for the quantitative control of NP dispersion in PNC films via modification of polymer adsorption was established in this study.

Research on Nano-Emulsion Relieving Coal Seam Water Block Damage

Hydraulic fracturing is the most effective reservoirstimulation techniques in the coalbed methane. However, the polymer in the fracturing fluid has a strong effect on the surface of the coal, causing the water lock damage as high as 70% to 90%. It is important to develop an efficient method for releasing coal seam water lock. In this paper, adsorption experiment, SEM, particle size experiment, core flow experiment, wettability and surface tension experiment are used to study the cause of coal seam water lock damage during fracturing and the effect of nano-emulsion on releasing water lock damage in coal seams. Experimental results show that after coal fracturing, the adsorption amount of polymer on the surface of coal is 14.81 mg/g. The large amount of hydrophilic polymer adsorption causes the pore radius of the coal to narrow. And the surface wettability changes from weak hydrophilic to strong hydrophilic, which increase the water lock damage. Compared with conventional slick water, fracturing fluid, the composite of nano-emulsion and fracturing fluid forms mixed micelles, which reduces the polymer adsorption capacity from 14.81 mg/g to 7.42 mg/g. After scanning by electron microscope, it is observed that the surface roughness of the rock sample is restored; The size of the nano-emulsion is about 10nm, and the very small volume can act deep in the pores of the coal seam; After using nano-emulsion, the gas/water interfacial tension is reduced by 45.1mN/m, and the wettability of coal is improved from hydrophilic to neutral, which reduces the capillary pressure in the pores of the coal and reduces the breakthrough pressure of coalbed methane by 11.1KPa; The water lock release rate is as high as 53.09%. The Nano-emulsion is an ideal choice to remove water lock damage.