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 CuSO 4 and sodium ascorbate in aqueous environment was used. The successful conversion of the precursors and the formation of networks were confirmed by 13 C-MAS NMR and FTIR spectroscopy. Network defects like multiple links and dangling chain ends were quantitatively investigated by 1 H double quantum (DQ) NMR spectroscopy.