Controlled Grafting of Cellulose Esters Using SET-LRP Process

Here, we present the first example of application of single-electron transfer living radical polymerization (SET-LRP) process to a controlled grafting of cellulose esters, cellulose diacetate (CDA), and cellulose acetate butyrate (CAB). The cellulose ester macroinitiators with various functionality densities have been prepared by acylation of the backbones with 2-bromoisobutyryl (BrIB) and dichloroacetyl (DCA) groups, respectively. Methacrylate monomers were polymerized using DCA-functionalized macroinitiators in the presence of pentamethyldiethylene triamine as a ligand. At 30 degrees C, the reaction is rather slow, reaching about 10% conversion after 3 to 6 h of polymerization, whereas the higher temperature (60 degrees C) perceptibly speeds up the polymerization so that methyl methacrylate (MMA) conversion is similar to 30% after 5 h. Graft copolymers with random-type and diblock-type grafts having amphiphilic character were also synthesized. For acrylate grafting (BuA and t-BuA), BrIB-functionalized macroinitiators are more convenient in a combination with a low concentration of Cu(0) and Me6TREN as a ligand and polymerization is detectably faster even at the lower temperature than that of MMA. Kinetic studies show living character of both the graftings. Important advantages of SET-LRP, compared with classic ATRP, are (i) higher polymerization rate, (ii) lower extent of recombination of the growing grafts and (iii) negligible coloration of the products with catalytic residua, so that the prepared polymers do not require additional careful purification. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 164-173, 2011