X-ray scattering studies on molecular structures of star and dendritic polymers

We studied the molecular shapes and structural characteristics of a 33-armed, star polystyrene (PS-33A) and two 3^rd-generation, dendrimer-like, star-branched poly(methyl methacrylate)s with different architectures (PMMA-G3a and PMMA-3Gb) and 32 end-branches under good solvent and theta (Θ) solvent conditions by using synchrotron small angle X-ray scattering (SAXS). The SAXS analyses were used to determine the structural details of the star PS and dendrimer-like, star-branched PMMA polymers. PS-33A had a fuzzy-spherical shape, whereas PMMA-G3a and PMMA-G3b had fuzzy-ellipsoidal shapes of similar size, despite their different chemical architectures. The star PS polymer's arms were more extended than those of linear polystyrene. Furthermore, the branches of the dendrimer-like, star-branched polymers were more extended than those of the star PS polymer, despite having almost the same number of branches as PS-33A. The differences between the internal chain structures of these materials was attributed to their different chemical architectures.