m-PEG4-phosphonic acid ethyl ester contains a phosphonic acid group. Phosphonic acid is used for surface modification. The hydrophilic PEG linker can increase the solubility of a compound in aqueous media and improve the hydrophilicity of the surfaces.
AxisPharm offers 5000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.