Static Properties of Noninteracting Comb Polymers in Dense and Dilute Media. A Monte Carlo Study

Abstract

We present an application of the cooperative motion algorithm (CMA) to ramified polymers. As a model for so-called comb polymers, we consider a main chain of fixed length to which a various number of side chains of different lengths are anchored. The effect of the molecular architecture on the side and on the main chain is investigated. We consider the two-and the three-dimensional case and compare numerical results obtained in dense melts and dilute solutions. The results show a strong influence of the molecular structure on the properties of the main chain. Initially Gaussian chains stretch and become non-Gaussian and non-Markovian. The side chains remain randomly coiled in threedimensional melts and stretch slightly in two dimensions and in three dimensional solutions.

On the shape of bottle-brush macromolecules: Systematic variation of architectural parameters

“…Within the error bars the result equals the value expected for a three-dimensional random walk under excluded volume conditions ͑3D-SAW͒ but is far away from the value s =3/4 expected for a two-dimensional SAW. This result is in disagreement with the small-angle x-ray scattering results of Schmidt and co-workers 3 14 ͑s-PS-b-PAMA͒ concluded from experimental results that the side chains adopt the same conformation as a free, linear chain as do Rouault and Borisov, 58 Gauger and Pakula, 59 and Shiokawa, Itoh, and Nemoto 60 ͑ s = 0.60͒ from their computer simulations. The results for the cross section radii of gyration are summarized in Table III including the value obtained for the sample with the shortest side chains.…”

Bottle-brush macromolecules in solution: Comparison between results obtained from scattering experiments and computer simulations

“…However, there is no agreement on what the effect of increasing side chain length is, on both, the persistence length of the backbone as well as of the overall brush structure. Predictions vary from a strong increase of the persistence length (backbone [12], brush [7,20,22,23]) over a slight increase (backbone [4,8,12e14], brush [4,8,21]) to no impact (backbone [2,5,6,9,11], brush [2]) on the persistence length with increasing side chain length. Computer simulations reveal that the impact of the side chain length on the backbone persistence depends on side chain flexibility.…”

“…Another question still under discussion is, whether the conformation of the side chains is unaffected by steric congestion or if the conformation is significantly inflicted in space. Predictions vary from a side chain conformation undergoing an (almost) three-dimensional (3D) self-avoiding random walk (SAW) [2,6,9,11,12,17,21] to a conformation being closer to that of a two-dimensional (2D) SAW [7,10,13,18,20,22]. In the first case, the brush radius is expected to increase with the end-to-end distance of the side chainsfN 3=5 s whereas in the latter extreme case a N 3=4 sdependence is expected.…”

Synthesis and solid state structures of macromolecular cylindrical brushes with varying side chain length

“…Small angle X-ray scattering intensity maxima related to the structure of cylindrical brushes in the melt have been reported only in one communication [23]. The conformations of cylindrical brushes in condensed systems have also been simulated [24] and the results have indicated an extension of the backbone, whereas the side chains remained in nearly unperturbed (Gaussian) states, in contradiction to simulations of single molecules in an athermal solvent which show an extension of both, main and side chains [25,26]. The present contribution investigates the intermolecular order of cylindrical brush polymers as function of side chain length utilizing the scattering methods.…”