MALDI/TOF/MS and SEC study of astromol dendrimers having cyano end groups

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometr y (MALDI/TOF/MS), size exclusion chromatography (SEC), and dilute solution viscometry were used to analyze the structure of three generations of Astro mol (trademark of DSM) dendrimers having cyano end groups. The molecular we ights, the defect contents, and. the structures of the "imperfect" dendrime rs were determined by MALDI/TOF/MS analysis with fractions collected using a SEC fraction collector. The peak broadening observed for these materials in SEC was studied by adding different co-solvents to the SEC mobile phase. The hydrodynamic radius of the dendrimers was measured both by dilute solu tion viscometry and by SEC universal calibration. Our radii data are compar able to previously published results for these dendrimers obtained by neutr on scattering and support the opinion that dendrimers have compact spherica l structures.