Regularly grafted polymer brush with degradable PCL backbone by ring-opening polymerization and “click” reaction: synthesis and self-assembly

A series of polymer brushes with degradable poly(caprolactone) (PCL) backbones were synthesized via “grafting onto” approach by combination of the ring-opening polymerization (ROP) and “click” reaction. First, P(αClCL) was synthesized by ROP and then the chloride was substituted by azide group to obtain P(N₃CL) backbone; then polymer brushes were synthesized by “click” reaction of alkynyl-PCL (ay-PCL) and alkynyl-PEO (ay-PEO) onto P(N₃CL). The products were characterized by gel permeation chromatography (GPC), FT-IR and ¹H NMR. Results indicated that the ay-PCL can be grafted onto P(N₃CL) backbone quantitatively at 1 : 1 ratio of alkynyl group to azide group and the branch was attached onto each repeating unit because of lower steric resistance and graft density. Also the amphiphilic polymer brushes with various hetero-branches of PEO/PCL ratios were synthesized by one-pot two-step process. The amphiphilic polymer brushes self-assembled into micelles with various PEO/PCL ratios and have potential application in drug loading and delivery.