Conformational Properties of End-Grafted Bottlebrush Polymers

This is the authors' abstract. We don't add key points for this paper.

Scaling analysis combined with free-energy calculations and molecular dynamics simulations of a coarse-grained bead-spring model have been used to study the structural properties of planar brushes formed by bottlebrush polymers tethered by ends to a flat surface. We find that the height H of end-grafted bottlebrushes undergoes a sequence of conformational changes emerging from the overlap between molecules at subsequent length scales upon increasing the number of bottlebrushes per unit surface area σ. We establish a relation between H and the structural parameters of bottlebrush architecture: degree of polymerization of backbone N bb and side chains N sc as well as grafting density z of side chains. We find that nonoverlapping bottlebrushes exhibit the behavior of isolated polymers in a good solvent with the height that is σ-independent and scales as ∝ (1 + zN sc ) 2/5 N bb 3/5 . Weakly overlapping bottlebrushes are similar to end-grafted linear polymers ( z = 0), and the height in this regime is ∝ σ 1/3 (1 + zN sc ) 2/3 N bb . Strongly overlapping bottlebrushes undergo a further increase in height, which is given by ∝ σ 2/7 z 6/7 N bb .