Linear-dendritic poly(ester)-block-poly(ether)-block-poly(ester) ABA copolymers constructed by a divergent growth method

The divergent synthesis of amphiphilic linear-dendritic block copolymers, LDBCs, that contain linear poly(ethylene glycol), PEG, and dendritic poly(benzyl ester)s is explored in this report. First [G1]- and second [G2]-generation LDBCs are constructed from PEG with a molecular weight of 5000 Da and 3,5-dioxy benzoate as the fundamental dendritic repeat unit. The synthetic strategy is based on the initial coupling of the protected monomer 3,5-bis(tert-butyldimethylsiloxy)benzoyl chloride to PEG (yield 98%) followed by removal of the silyl protective groups under mild conditions to give (HO)(2)[G1]-PEG5K-[G1](OH)(2), yield 97%. Subsequent coupling of the acid chloride monomer proceeds with 96% yield, and the final deprotection yields 94% of pure (HO)(4)[G2]-PEG5K-[G2](OH)(4). Two different chemical reactions (acid-alcohol and alcohol-halide interaction) are evaluated as possible routes to facile surface modification of the aromatic polyester monodendrons.