HYPERBRANCHED MACROMOLECULES VIA A NOVEL DOUBLE-STAGE CONVERGENT GROWTH APPROACH

A novel double-stage convergent growth approach for the preparation of dendritic macromolecules is described. In the first stage, convergent growth with 4,4-bis(4'-hydroxyphenyl)pentanol as the building block is used to create symmetrical dendritic structures containing a large number of phenolic ''surface'' functionalities. In the second stage of growth, these polyphenolic dendritic macromolecules are utilized as cores for the attachment of other dendritic macromolecules, derived from 3,5-dihydroxybenzyl alcohol, that contain a single benzylic bromide reactive group at their focal point. This two-stage process affords hyperbranched spherical macromolecules consisting of a flexible inner core surrounded by a more rigid outer layer. The double-stage convergent growth approach allows for the preparation of larger dendrimers in less time and with greater ease than the single-stage approach while retaining the advantages of near monodispersity and ease of purification and characterization.