m-PEG4-(CH2)8-phosphonic acid 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 4000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.