Amphiphilic hydrogels constructed by poly(ethylene glycol) and shape-persistent dendritic fragments

This paper describes the synthesis of amphiphilic hydrogels with highly shape persistent cross-link junctions using linear blocks, such as poly(ethylene glycol), PEG, and perfectly branched (dendritic) macromolecules. The synthetic strategy is based on the reaction of PEG with isocyanate or epoxy end groups as the hydrophilic component and hydrophobic dendritic poly(benzyl ethers) with amino groups at the periphery. It is found that the efficiency of the cross-linking reaction depends on the nature of chemical reaction used and the stoichiometric ratio of the two building blocks. The swelling of the gels formed is affected by the relative PEG content and by the polarity of the medium and the temperature, and it varies between 1.2 and 16.7 (by weight). The influence of various factors on the degree of crystallinity and phase segregation is also discussed.