Theoretical Study of Comb Polymers Adsorption on Solid Surfaces

Abstract

We propose a theoretical investigation of the physical adsorption of neutral combpolymers with an adsorbing skeleton and non-adsorbing side-chains on a flat surface.Such polymers are particularly interesting as "dynamic coating" matrices for bioseparations, especially for DNA sequencing, capillary electrophoresis and lab-on-chips. Separation performances are increased by coating the inner surface of the capillaries with neutral polymers. This method allows to screen the surface charges, thus to prevent electro-osmosis flow and adhesion of charged macromolecules (e.g. proteins)on the capillary walls. We identify three adsorption regimes: a "mushroom" regime, in which the coating is formed by strongly adsorbed skeleton loops and the side-chains anchored on the skeleton are in a swollen state, a "brush" regime, characterized by a uniform multi-chains coating with an extended layer of non-adsorbing side-chains and a non-adsorbed regime. By using a combination of mean field and scaling approaches, we explicitly derive asymptotic forms for the monomer concentration profiles, for the adsorption free energy and for the thickness of the adsorbed layer as a function of the skeleton and side-chains sizes and of the adsorption parameters. Moreover, we obtain the scaling laws for the transitions between the different regimes. These predictions can be checked by performing experiments aimed at investigating polymer adsorption, such as Neutron or X-ray Reflectometry, Ellipsometry, Quartz Microbalance, or Surface Force Apparatus.

Conformational studies of bottle-brush polymers absorbed on a flat solid surface

“…Alternative information on this thickness can be obtained when one simply studies the monomer density profile P (z), which again can also be resolved distinguishing contributions from the backbone only, from the side chains only, or even from the free chain ends of the side chains only (Figs. [10][11][12][13][14].…”

“…Of course, under many circumstances these functions of bottle-brushes occur when they are attached to a substrate surface (e.g. a cell membrane in a biological context, or an inorganic flat solid surface for nano-technological applications, including also special surface coatings [13]). Bottle-brush molecules attached to surfaces are also of particular interest, since additional experimental tools become available to study their structure (e.g., one can directly visualize their large-scale conformation by scanning force microscopy [3,14,15], or one can use atomic force microscopes to measure force vs. extension curves [16]).…”

Viscoelastic signature of physisorbed macromolecules at the solid–liquid interface

“…The adsorption can be classified typically into two types: chemisorption which involves chemical bonding of molecules to the interface, and physisorption which relies on weak forces such as Van der Waals type interactions with the interface. There has been broad interest in investigating a wide variety of chemical and biological systems chemisorbed at various types of solid-liquid interfaces [12][13][14][15][16][17][18], but the study of physisorption of molecules at solid-liquid interface is relatively scarce, even though the phenomenon is also a key mechanism influencing many physical, chemical, and biological processes at solid-liquid interfaces [19][20][21][22][23][24][25][26]. The difficulties in the study of physisorption of molecules at solid-liquid interface are mainly due to the strong interaction of the adsorbed molecules with solution molecules that are often comparable to that with the interface itself.…”

Effects of chain architectures on the surface structures of conjugated rod-coil block copolymer brushes

“…For example, both Y-shaped block copolymer brushes and comblike block copolymer brushes have been observed to possess distinct surface structures and properties from polymer brushes with linear block copolymer tethered to the substrate through chain ends. [32][33][34][35][36][37] Note that polymer brushes based on rod-coil block copolymers have rarely been studied because of the synthetic difficulty of conjugated backbones via surface-initiated polymerization. However, rod-coil block copolymers consisting of a -conjugated polymer as the rod and a flexible block as the coil are a unique and interesting class of nanomaterials because it opens the way for the tuning of both molecular organization and optical properties of these materials by controlling their aggregation structures.…”