t-Boc-N-amido-PEG-amine, MW 5K is a PEG polymer with a t-Boc protecting group and a free amine. The t-Boc can be removed with strong acid to yield the free amine.
AxisPharm offers 5000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.