Chemoenzymatic synthesis amphiphilic H-shaped copolymer and its self-assembly behavior

ABA triblock copolymers were synthesized by dihydroxyl-capped PEO initiated enzymatic ring-opening polymerization (eROP) of ε-CL in the presence of biocatalyst Novozyme 435. The chains ended with hydroxyl of block copolymers were modified by the esterification of 2,2-dichloro acetyl chloride (DCAC) to obtain the tetrafunctional macroinitiator, which was used in the ATRP of 4-vinylpyridine (4-VP). CuCl/HMTETA was used as the catalyst system in the ATRP of 4-VP to acquire the H-shaped block copolymers (PVP)₂-b-PCL-b-PEG-b-PCL-b-(PVP)₂. The H-shaped block copolymers were characterized by FTIR, NMR, and GPC. Copolymers with high molecular weights (M _n = 46121 g/mol) and low polydispersities (M _w/M _n = 1.30) were prepared. Moreover, the morphology of the copolymer was examined with dynamic light scattering (DLS) and atomic force microscopy (AFM). Spherical micelles with a diameter of 70 nm in aqueous solution were obtained.