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

We addressed the structure of bottle-brush macromolecules under good solvent conditions by means of scattering techniques and computer simulations. Architectural parameters, such as backbone length, side chain length and side chain stiffness were varied systematically. A consistent description of the form factors was achieved by describing the bottle-brush polymers as flexible cylinders with internal density fluctuations. The model leads to direct conclusions about parameters, such as the brush persistence length, describing the overall shape of the bottle-brush polymers. Indirect conclusions about the side chain and backbone conformation can be drawn. Experimental results were compared to those obtained from computer simulations carried out for single bottle-brush polymers using the cooperative motion algorithm. The simulation gives direct access to the pair correlation function, allowing an independent determination of the form factor. In addition direct information about the side chain and backbone conformation can be obtained. The critical parameter for lyotropic behavior of bottle-brush polymer solutions is the ratio of brush persistence length to diameter which should be of order 10 or larger. Thus the discussion of the results is focused on the impact of the architectural parameters on the persistence of the bottle-brush polymers. Experimental results on the lyotropic behavior of a bottle-brush polymer are presented.