Enzyme-catalyzed transesterification of several cellulose solids in organic
media have been investigated. Several protease enzymes were made soluble i
n organic media through ion-paired enzyme-surfactant complexes. Subtilisin
Carsberg was found to be catalytically active in the transesterification of
cellulose with vinyl propionate and vinyl acrylate in anhydrous pyridine.
The ester carbonyl groups in acylated cellulose derivatives were confirmed
by Fourier transform infrared spectroscopy. The surfaces of these cellulose
derivatives became hydrophobic as demonstrated by increased water-contact
angles. The enzyme-catalyzed transesterification was confirmed to regiosele
ctively target the primary hydroxyl group of cellulose by reactions on spec
ifically substituted cellulose. The cellulose esters from enzyme-catalyzed
transesterification could be hydrolyzed partially by the same enzyme in aqu
eous media, and were thus biodegradable. Surface grafting of cellulose acry
late was demonstrated using azobisisobutylonitrile-initiated polymerization
of acrylonitrile in dimethylformamide. Polyacryonitrile (PAN)-g-cellulose
shows a differ ent thermal behavior from cellulose, homopolymer PAN, and PA
N/cellulose blends. The grafted PAN on PAN-g-cellulose at a 16% grafting ad
d-on is incapable of cyclization. (C) 2001 John Wiley & Inc, Inc.