Controllable photophysical properties and self-assembly of siloxane-poly(amidoamine) dendrimers

Abstract

Poly(amidoamine) dendrimers are typical luminescent polymers containing unconventional chromophores. A series of novel siloxane–poly(amidoamine) (Si–PAMAM) dendrimers were synthesized and investigated in this study. Their structures and properties were determined by NMR, XPS, LC/MS, and fluorescence spectroscopy. The introduction of Si–O–Si units in Si–PAMAM changed the photophysical properties of the dendrimers. The luminescence of Si–PAMAM was associated with the aggregation of its carbonyl groups, which was caused by N → Si coordination bonds. The strong blue luminescence of Si–PAMAM was also studied in detail, and it was found to be quite different from the ethanediamine-based poly(amidoamine). Results indicated that the luminescence of Si–PAMAM could be controlled by solvents, acids, metal ions, temperature, or degree of aggregation of the carbonyl groups. Moreover, micron-sized tubes composed of Si–PAMAM molecules were generated and found in water/methanol solution.