Adsorption of Polymer-Tethered Particles on Solid Surfaces

Abstract

We explore the behavior of polymer-tethered particles on solid surfaces using coarse-grained molecular dynamics simulations. Segment–segment, segment–core, and core–core interactions are assumed to be purely repulsive, while the segment–substrate interactions are attractive. We analyze changes in the internal structure of single hairy particles on the surfaces with the increasing strength of the segment–substrate interactions. For this purpose, we calculate the density profiles along the x , y , z axes and the mass dipole moments. The adsorbed hairy particles are found to be symmetrical in a plane parallel to the substrate but strongly asymmetric in the vertical direction. On stronger adsorbents, the particle canopies become flattened and the cores lie closer to the wall. We consider the adsorption of hairy nanoparticles dispersed in systems of different initial particle densities. We show how the strength of segment–substrate interactions affects the structure of the adsorbed phase, the particle–wall potential of the average force, the excess adsorption isotherms, and the real adsorption isotherms.

Shape Transformations and Self-Assembly of Hairy Particles under Confinement

“…They observed regular hexagonal two-dimensional structures with different spacing of the particles depending on the grafting density. In our previous work, we found the same structure [ 29 ].…”

“…We considered several wall separations ranging from to . Similar values of the parameters were assumed in the previous simulations of polymer-tethered particles [ 21 , 22 , 28 , 29 , 35 ].…”

“…Experimental and theoretical studies [ 23 , 24 , 25 , 26 , 27 , 28 , 29 ] proved that the presence of a solid surface affects the structure of a single hairy particle, as well as the morphology of monolayers deposited on substrates. Among the most important parameters that influence the structure of hairy particles near surfaces are the number of tethered chains, their lengths, and the strength of interactions with the substrate.…”

“…Unfortunately, there are no experimental data for such systems. However, numerous investigations show that the solid surface influences the morphology of films built of hairy nanoparticles on substrates [ 23 , 24 , 27 , 29 ]. In the sub-monolayer region, the surface films investigated by Che et al [ 23 ] contained strings of particle agglomerates, whereas the monolayers consisted of well-ordered hexagonal lattices.…”

“…Various combinations of interaction parameters were assumed in the simulations of hairy particles in bulk systems. These models are summarized in [ 29 , 36 ]. Furthermore, different interactions with the surface can be considered: (i) all repulsive interactions, (ii) all attractive interactions, (iii) attractive core-substrate interactions and repulsive segment-substrate interactions, and inversely, (iv) attractive segment-substrate interactions and attractive segment-substrate interactions.…”