Effect of dense grafting on the backbone conformation of bottlebrush polymers:: Determination of the persistence length in solution

The effect of dense grafting on the polymer brush's conformation is studied by small-angle neutron scattering on well-defined branched copolymers. We have determined the persistence length l(p) of the backbone of poly(chlorovinyl ether) grafted with polystyrene (PCEVE-g-PS) copolymers. In a good solvent, this length lp can be directly obtained from the scattering vector q* at which the polymer chain locally behaves as a rod; i.e., its form factor enters the q(-1) variation regime. This method is first applied to a linear PCEVE polymer, as reference. Then, we compare to the branched copolymers by using the matching condition for the PS branches in order to only measure the form factor of the PCEVE backbone. From the flexible linear chain to the bottlebrush-like polymer, the persistence length increases from 12 to 110 Angstrom.