Unusual conformation of molecular cylindrical brushes strongly adsorbed on a flat solid surface

Abstract

Conformational properties of comb-like polymers strongly adsorbed on a flat solid surface were investigated using computer simulation and scanning force microscopy. The computer simulation showed that the macromolecules with asymmetric distribution of the side chains relatively to the backbone are effectively in a collapsed state even under conditions of a good solvent. They formed peculiar helical superstructures which could be observed by scanning force microscopy of cylindrical brushes of polymethylmethacrylate on mica.

Stiffness and conformations of molecular bottle-brushes strongly adsorbed on a flat surface

“…The exponent ν = 0.5 of N means that the characteristic size of such a spiral is closer to the one of a 2D densely packed chain with aN/D monomer units of size D ∼ aM (aB/∆ 2 ) 1/3 . Our analysis for the one-sided brush is in good agreement with computer simulation results obtained by Khalatur and co-workers [12,13]. They considered 2D bottlebrush molecules for which the lengths of the backbone and side chains were varied from 32 to 2048 and from 1 to 48 units, respectively.…”

“…Another example of asymmetrical chain distribution is a brush with strongly incompatible side chains of different species segregated with respect to the backbone. In these cases strongly adsorbed cylindrical brush molecules can twist and adopt spiral-like conformation [12,13], see Figure 1. The only reason for the twisting of the adsorbed brush molecules is an asymmetrical distribution of strongly adsorbed side chains: the number of grafted chains adsorbed on both sides with respect to the backbone is not equal.…”

Conformational properties and dynamics of molecular bottle-brushes: A cellular-automaton-based simulation

“…On the other hand, two-dimensional branched macromolecules with one-sided branches are effectively in a collapsed state even under conditions of a good solvent that is due to the formation of regular spiral-like conformations. It should be noted that the two-dimensional spiral-like structures for comblike copolymers strongly adsorbed on a flat solid surface have been recently observed experimentally using the scanning force microscopy 38) . (ii) Comparison of the simulated data with the predictions of the scaling model indicates that the latter is valid in describing the mean dimensions of the backbone, R, as a function of side-chain length, n, and interbranch spacing, m. In particular, it is found that the value of R scales with n and m as R l n 0.398 and R l m -0.320 for sufficiently large n and high grafting densities.…”

Atomic force microscopy observation of a helical poly(phenylacetylene) bearing aza‐18‐crown‐6 ether pendants induced by amino acids

“…Although this coincidence in the AFM images is remarkable, we have to take into consideration the fact that the kinetic process during the adsorption of the polymer on the mica surface is associated with the helical conformation in solution. 49 …”