Structural properties of star-like dendrimers in solution

We measured the form factor of star-like poly-ε-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 Rg 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 ≈ 5/3 (loose, polymeric structure) and that expected for a high-functionality star P ≈ 3 (compact shape).