Structural properties of star-like dendrimers in solution

We measured the form factor of star-like poly-epsilon-caprolactone dendrimers under good solvent conditions with small-angle neutron scattering (SANS). The parameters varied in the experiment were the dendrimer generation g = 1, 2, 3 and the number of segments between the branching units n = 5, 10, 15, 20. The results are discussed in the frame work of the Beaucage model from which we cannot only derive the radius of gyration R-g of the dendrimers but also their fractal dimensions. Decreasing the number of spacer units between the branching points results in a strong stretching of the dendrons. The fractal dimension increases monotonically with increasing generation and spacer number between the limit expected for a low-functionality star P approximate to 5/3 (loose, polymeric structure) and that expected for a high-functionality star P approximate to 3 (compact shape).