Graft copolymers via ROMP and Diels-Alder click reaction strategy

Anthracene-functionalized oxanorbornene monomer and oxanorbornenyl polystyrene (PS) with ω-anthracene end-functionalized macromonomer were first polymerized via ring-opening metathesis polymerization using the first-generation Grubbs' catalyst in dichloromethane at room temperature and then clicked with maleimide end-functionalized polymers, poly(ethylene glycol) (PEG)-MI, poly(methyl methacrylate) (PMMA)-MI, and poly(tert-butyl acrylate) (PtBA)-MI in a Diels-Alder reaction in toluene at 120 °C to create corresponding graft copolymers, poly(oxanorbornene)-g-PEG, poly(oxanorbornene)- g-PMMA, and graft block copolymers, poly(oxanorbornene)-g-(PS-b-PEG), poly(oxanorbornene)-g-(PS-b-PMMA), and poly(oxanorbornene)-g-(PS-b-PtBA), respectively. Diels-Alder click reaction efficiency for graft copolymerization was monitored by UV-vis spectroscopy. The dn/dc values of graft copolymers and graft block copolymers were experimentally obtained using a triple detection gel permeation chromatography and subsequently introduced to the software so as to give molecular weights, intrinsic viscosity ([n]) and hydrodynamic radius (R_h) values.