Oxidation and grafting of benzyl and ethyl cellulose

The preparation of graft copolymers of benzyl and ethyl cellulose was attempted through the initiation of vinyl polymerization by the cellulose ether hydroperoxides. The benzyl and ethyl cellulose ether hydroperoxides were prepared in solution by oxidizing with air. The polymer underwent severe chain degradation concurrently with hydroperoxide formation. The relative rates of these reactions differed for the benzyl and ethyl cellulose ether and also depended on the nature of the solvent. As a result, the hydroperoxide content of the polymer could be increased by lengthening the oxidation time, but the number of hydroperoxide groups per chain increased much more slowly. With the use of ethyl cellulose hydroperoxide as initiator, a kinetic study of styrene polymerization was made. Rates of hydroperoxide decomposition were also measured so that the efficiency as initiator could be determined. These rate data indicated an efficiency of 60–90% and considerable chain transfer to the hydroperoxide groups. In the preparation of graft copolymer the amount of actual graft was determined to be very small. Poor yields of graft copolymer were attributed to an unfavorable competition in the reactions of initiation and chain transfer and to the degraded chain length of the cellulose ether hydroperoxide. Substantiating evidence for the occurrence of nongrafting initiation and transfer reactions came from an infrared study of low molecular weight polystyrene initiated with α‐isobutoxyethylhydroperoxide.