Polymer Grafting Onto Polyurethane Backbone via Diels-Alder Reaction

The aliphatic polyurethane with pendant anthracene moieties (PU-anthracene) was prepared from polycondensation of anthracen-9-yl methyl 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate (anthracene diol), 1 with hexamethylenediisocyanate in the presence of dibutyltindilaurate in CH2Cl2 at room temperature for 10 days. Thereafter, the PU-anthracene (M-n,M-GPC = 12,900 g/mol, M-w/M-n = 1.87, relative to PS standards) was clicked with a linear -furan protected-maleimide terminated-poly(methyl methacrylate) (PMMA-MI) (M-n,M-GPC = 2500 g/mol, M-w/M-n = 1.33), or -poly(ethylene glycol) (PEG-MI) (M-n,M-GPC = 550 g/mol, M-w/M-n = 1.09), to result in well-defined PU-graft copolymers, PU-g-PMMA (M-n,M-GPC = 23800 g/mol, M-w/M-n = 1.65, relative to PS standards) or PU-g-PEG (M-n,M-GPC = 11,600 g/mol, M-w/M-n = 1.45, relative to PS standards) using Diels-Alder reaction in dioxane/toluene at 105 degrees C. The Diels-Alder grafting efficiencies were found to be over 93-99% using UV spectroscopy. Moreover, the structural analyses and the thermal transitions of all copolymers were determined via H-1 NMR and DSC, respectively. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 521-527