Well-defined brush copolymers with high grafting density of amphiphilic side chains by combination of ROP, ROMP, and ATRP

This work reports a facile strategy for the preparation of a novel well-defined brush copolymer with two different grafts distributed on the same unit along the backbone via combination of three controlled polymerization methods, ring-opening polymerization (ROP), ring-opening metathesis polymerization (ROMP), and atom transfer radical polymerization (ATRP) based on the synthesis of the heterotrifunctional inimer, 2-hydroxymethyl-3-(2- bromoisobutyryloxymethyl)-5-norbomene (NBE-OH/Br). ROP of 6-caprolactone initiated by NBE-OH/Br was carried out to generate macroinimer, norbomene-gra//-poly(E-caprolactone)/Br (NBE-g- PCL/ Br). The grafting-through strategy was then employed to construct the polymer backbone, poly(norbornene)graft-poly(ε-caprolactone)/Br (PNBE-g-PCL/Br) via ROMP of the norbornene-terminated macroinimer NBE-g-PCL/Br. Finally, the grafting-from route was used for the synthesis of amphiphilic grafted brush copolymer, poly(norbomene)-graft-poly(ε-caprolactone)/poly(2-(dimethylamino)ethyl methacrylate) (PNBE-g-PCL/PDMAE-MA) by ATRP of 2-(dimethylamino)ethyl methacrylate using bromo-functionalized ROMP product PNBE-#-PCL/Br as macroinitiators, containing one hydrophobic PCL graft and one hydrophilic PDMAEMA graft on each unit of the backbone.