Silyl celluloses: A new class of soluble cellulose derivatives

Abstract

Abstract Two general methods for the silylation of cellulose have been developed. Silyl amides undergo silyl—proton exchange reactions with cellulose in polar solvents leading to displacement of 80–90% of the hydroxyl protons by silyl groups. The same products are obtained by reaction of the corresponding chlorosilanes with cellulose in pyridine; however, di‐ and trifunctional impurities present in commercial chlorosilanes have to be removed by scavenging with a carbohydrate in order to avoid crosslinking. Cellulose derivatives with trimethylsilyl, dimethylphenylsilyl, methyldiphenylsilyl, and γ‐cyanopropyldimethylsilyl substituents have been prepared by both methods. The properties of the new soluble polymers are largely dependent on the nature of the silyl substituents. The silyl celluloses exhibit a relatively high degree of hydrolytic stability; methyldiphenylsilyl cellulose is hydrolytically stable even under severe conditions.