Synthesis of well-defined dendrimer-like branched polymers and block copolymer by the iterative approach involving coupling reaction of living anionic polymer and functionalization

The first-, second-, and third-generation dendrimer-like branched poly(methyl methacrylate)s (PMMA)s were synthesized by an iterative divergent approach which involves a coupling reaction of alpha-functionalized living anionic PMMA with chain-end-functionalized PMMA with benzyl bromide moieties and a transformation reaction of the tent-butyldimethylsilyloxymethylpheny groups into benzyl bromide functionalities. The iterative reaction sequence could be repeated three times without problem to afford a series of three generations dendrimer-like branched PMMAs with well-defined architectures and precisely controlled chain lengths. Moreover, an amphiphilic dendrimer-like branched block copolymer was synthesized successfully in a similar manner by using the living anionic polymer of the protected 2-hydroxyethyl methacrylate (HEMA) instead of living anionic PMMA at the final reaction stage. The resulting polymer was made of the inner 1, 4, and 8 PMMA segments and the outer 16 poly(HEMA) segments. The solution behaviors were followed by H-1 NMR spectra. The formation of micelles was strongly indicated in both CDCl3/CD3OD (98/2, v/v) and CDCl3/CD3OD (5/95, v/v) mixtures.