Cationic polyesters bearing pendent amino groups prepared by thiol-ene chemistry

A straightforward approach based on thiol-ene click chemistry was used to prepare novel functional polyesters containing amino groups. First, a series of well-defined alkene-functional poly(epsilon-caprolactone)s were prepared by ring-opening polymerization of alpha-allyl-epsilon-caprolactone with epsilon-caprolactone in toluene and in bulk using tin 2-ethylhexanoate as catalyst. These functional polyesters were fully characterized by H-1 NMR, GPC, and MALDI-TOF MS. The resulting random copolyesters were obtained with a wide range of molar masses from 3000 to 50 000 g mol(-1) and a good incorporation of the alpha-allyl-epsilon-caprolactone monomer unit. Then, thiol-ene reaction of alkene-functional PCL with the 2-(Boc-amino)ethanethiol was used to prepare efficiently polyesters bearing protected amino groups without chain degradation. Finally, cationic and water-soluble polyesters bearing free amino groups were recovered by cleavage of the Boc protecting group. These aminated polyesters were characterized by H-1 NMR in deuterated water.