Conformational changes of linear-dendrimer diblock copolymers in dilute solution

The conformation of linear-dendrimer hybrid diblock copolymers in solution has been studied using both small-angle neutron scattering and dynamic light scattering. The diblock consisted of a fourth-generation benzyl ether dendrimer with different molecular weight polystyrene bonded to the focal point of the dendrimer; the total molecular weight ranged from 20 to 100 kDa. In agreement with previous studies, it was found that this dendron, without a linear chain attached, alters its size upon solvent change. The addition of a polystyrene chain to the focal point of a dendrimer was also found to have an effect on the dimensions and shape of the dendrimer block. A low-molecular-weight polystyrene chain swelled the dendrimer without perturbing its native spherelike conformation. However, at larger polystyrene molecular weights, the linear block manipulates a transition of the dendrimers' morphology form spherelike to an extended conformation. Control of this shape and size change has potential for these unique macromolecular architectures to function as a novel molecular building block.