NMR Characterization of PEG Networks Synthesized by CuAAC Using Reactive Oligomers

Well-defined poly(ethylene glycol) (PEG) networks were synthesized using copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Two types of PEG network structures were prepared (i) by linking two three-arm star PEG oligomers together and (ii) by connecting three-arm PEG star units with bifunctional linear PEG oligomers of different molar masses. End-group functionalization of PEG oligomers to azide and alkyne moieties was performed while for CuAAC the catalytic system of CuSO4 and sodium ascorbate in aqueous environment was used. The successful conversion of the precursors and the formation of networks were confirmed by C-13-MAS NMR and FTIR spectroscopy. Network defects like multiple links and dangling chain ends were quantitatively investigated by H-1 double quantum (DQ) NMR spectroscopy.