The syntheses and rheological behavior of ethyl bydroxyethyl cellulose (EHEC)-based graft-copolymers were studied. Copolymers were prepared by grafting EHEC with acrylamide (Aam) via reversible addition fragmentation chain transfer (RAFT) polymerization. Hydroxyl groups of EHEC were esterified with a carboxylic acid functional chain transfer agent (CTA) to prepare EHEC-macroCTAs with different degrees of substitution. EHEC-macroCTAs were characterized by ATR-FTIR, C-13 NMR, and SEC, and elemental analysis was used to quantify the degree of CTA substitution. EHEC-macroCTAs with different degrees of substitution were copolymerized with acrylamide by "grafting from" technique. Formation of new cellulose-based copolymers was comprehensively confirmed by H-1 NMR, ATR-FTIR, and SEC measurements. Further, the associations of EHEC-g-PAam, copolymers in water were studied at various concentrations and temperatures by means of UV-vis spectroscopy, fluorescence spectroscopy, and rheological measurements. The results indicate that copolymers have both intra and intermolecular association in water depending on the amount of grafts. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1869-1879, 2009