Propargyl-PEG2-acrylate is a PEG derivative containing a propargyl group and an acrylate group. The propargyl group can be reacted with azide-bearing compounds or biomolecules via copper catalyzed azide-alkyne Click Chemistry to yield a stable triazole linkage. The acrylate group enables Michael addition. The hydrophilic PEG spacer increases solubility in aqueous media.