Carbohydrate Research, 225 (1992) 301-320 Elsevier Science Publishers B.V., Amsterdam 307 Solution interactions and rheology of N-[2-(glycosyloxy)- ethyllchitosan derivatives* Kevin R. Holme+, Laurance D. Hall’ Department of Chemistry, The University of British Columbia, Vancouver, BC V6T 1 Y6 (Canada) R. Alex Speers** and Marvin A. Tungtt Department of Food Science, The University of British Columbia, Vancouver, BC V6T I Y6 (Canada) (Received April 15th, 1991; accepted for publication in revised form, September lst, 1991) zyxwvutsrqponmlkjihgf ABSTRACT Aqueous solutions of N-[2-(glycosyloxy)ethyl]chitosans have been studied by steady-shear rheo- metry over an intermediate shear-rate range (ll2500 s-l). The power law has been found to be a suitable model for characterizing the rheological behavior of these solutions over the shear-rate range examined. In general, solution viscosity and pseudoplasticity increased as the degree of substitution (d.s.) decreased. This trend also applied to measurements of intrinsic viscosity. The solutions ofderivatives having pendant lactose residues were less viscous than those having equivalent pendant monosaccharide substitution. It was also found that derivatives bearing neutral monosaccharide branches interacted with xanthan polymer in solution. INTRODUCTION Interest in branched polysaccharides arises in part from some of their useful physical properties in water solution - . ’ 3 Similarly, motivation for modifying poly- saccharides stems in part from a desire to impart or control solution properties4. Some methods for preparing branched polysaccharide derivatives have been reported”, and discussed with regard to their advantages and disadvantages4. In the case of natural branched polysaccharides, the relatively limited array of structurally related materials makes it difficult to establish a predictive understanding of structure-property trends. Conversely, most chemically modified derivatives are often too complex to establish any correlation between their structure and function. A better understanding of such an interrelationship is desirable, and would ultimately lead to the ability to tailor solution properties by structural variation of the polymer molecules. * Part II of the series N-[2-(glycosyloxy)ethyl]chitosan derivatives: For part I, see ref. 9. + Current address: IBEX Technologies, 6100 Royalmount Ave., Montreal, Quebec H4P 2R2, Canada. * Current address: Laboratory for Medicinal Chemistry, Level 4 Radiotherapeutic Center, Addenbrookes Hospital, Hills Road, Cambridge CB2 2QQ, United Kingdom. ** Current address: Department of Food Science, Acadia University, Wolfville, Nova Scotia BOP 1X0, Canada. ++ Current address: Department of Food Science and Technology, Technical University of Nova Scotia, 1360 Barrington St., P.O. Box 1000, Halifax, Nova Scotia B3J 2X4, Canada. 000%6215/92/$05.00 @ 1992 - Elsevier Science Publishers B.V. All rights reserved.