Amine PEG

H2N-(CH2)3O-PEG-(CH2)3-NH2, Mw 2,000   
H2N-(CH2)3O-PEG-(CH2)3-NH2, Mw 3,400

Make to order

H2N-(CH2)3O-PEG-(CH2)3-NH2, Mw 10,000   
H2N-(CH2)3O-PEG-(CH2)3-NH2, Mw 20,000   
H2N-(CH2)3O-PEG-(CH2)3-NH2, Mw 30,000