HYDROGELS FROM POLYSACCHARIDES .1. CELLULOSE BEADS FOR CHROMATOGRAPHIC SUPPORT

Cellulosic hydrogels in bead form were prepared by dropwise addition o f cellulose solutions in N,N-dimethylacetamide (DMAc) and lithium chlo ride (LiCl) to azeotropic methanol or isopropanol as nonsolvent. Bead properties were examined in relation to cellulose solution concentrati on, viscosity, and molecular weight. Bead properties were defined in t erms of solids content, flow characteristics, mechanical strength, bea d size, and pore dimensions. Results suggest that (a) beads can be pre pared with solids content ranging from 2 to 12 wt %, depending on solu tion concentration; (b) uniform spherical shapes require a viscosity r ange between 100 and 300 cS; (c) beads can be produced in different si zes, within the diameter range of 100 to 1,500 mu m; (d) linear flow v elocities of packed bead columns are in the range of 70 to 350 cm/min; and (e) pore sizes of beads vary between 8 to 200 Angstrom. Beads wit h low cellulose concentration show a wide fractionation range of up to 200,000 g/mol for polyethylene oxide. (C) 1996 John Wiley & Sons, Inc .