Roughening up polymer microspheres and their diffusion in a liquid

Abstract

A simple, versatile approach for the roughening of polymer microparticles surfaces via a deformation technique in the presence of an inorganic matrix is presented here. The process consists of straightforward steps: (1) preparation of a bicomposite colloidal sol, that is polymer particles and inorganic particles, dispersed in a liquid, (2) drying of the mixture onto a suitable hard substrate, (3) heating the dried film above the glass transition temperature of the polymer, and (4) re-dispersion and chemical etching of the inorganic medium. The primary driver is capillary imbibition of the polymer melt into the inorganic colloidal template. In addition, 2D particle tracking experiments of dispersed rough particles in water were performed to probe the diffusional behaviour of the roughened objects in comparison with their smooth precursors. We show that, despite large scale roughness (up to 10% asperity size with respect to particle diameter), Stokes law is obeyed and the particle motion can be modelled simply with the Stokes-Einstein-Sutherland relation.

Improving the engine power of a catalytic Janus-sphere micromotor by roughening its surface

“…It was initially intriguing to us that micromotors with large surface deformations had a similar propulsion velocity to their non-deformed cousins as we expected a larger catalytic surface area to promote faster motion. Large surface deformations lead to an effective diameter increase of ~40% as found in a previous study 27 . If we consider no change in the phoretic mechanism and ignore effects of the altered particle shape, an equivalent reduction in propulsion velocity should be observed, ∝ v r 1/ 19 .…”

“…All are comparable to the theoretical values (D = 0.27 to 0.41 μm 2 s −1 ) from the Stokes-Einstein-Sutherland (S-E-S) relation, D = k B T/6πηr, for colloids of this size range (r = 0.6 to 0.9 μm). The differences between these D values is down to a change in the effective hydrodynamic radii of the deformed particles, in that the more deformed the particle is the larger its effective diameter (measured from the two furthest peripheral points) and therefore the lower D is, as shown previously 27 .…”

“…Particles were tracked near the underlying glass surface as they tend to sediment here due to a density mismatch between the poly(styrene) microspheres and water, added to by the presence of the heavy Pt cap 28 . For 2D translational Brownian motion any boundary effects from the underlying glass surface are small 27,29 and the significant mass anisotropy of the Pt cap does not have a large effect (Note: it does have a marked effect in 1D) 28,30 . Applying linear fits to the mean-squared-displacement (MSD), ∆x t 2 , (Fig.…”

Improving the engine power of a catalytic Janus-sphere micromotor by roughening its surface

“…Here, we introduce a methodology to access PS-Pt micromotors with irregular surface morphologies and investigate their propulsive behaviour. The self-propelling colloids are made from spherical PS precursors which are roughened using a recently established physical route 27 , prior to Pt deposition by sputtering. With this strategy the underlying surface chemistry should be practically identical in each case and we can make reasonable conclusions about the propulsive mechanism and magnitude.…”

Preparation and properties of multilayer assembled polymer gel microsphere profile control agents

“…At present, it is an important direction and a hotspot in the research of water plugging profile control agents . Polymer composite microspheres are in the nano/micron scale and have a stable structure, with its inorganic component bonded with the organic polymer via chemical bonds; thus, the microspheres have both high plugging strength of the inorganic components and the expansion, deformation, and migration ability of the polymer components . In addition, they have several advantages such as temperature resistance, mineralization resistance, online injection, low system viscosity, and sewage preparation, as well as the characteristics of “feed in, block up, and move” .…”