A variety of new cellulose solvents was investigated toward their potential as media for the functionalization of the polyglucane. Thus, mixtures of dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF), N-methylmorpholine-N-oxide (NMMNO)/DMSO, melts of LiClO4.3H(2)O, and aqueous solutions of Ni(tren)(OH)(2) [tren = tris(2-aminoethyl)amine] were applied as reaction media. In case of the new solvent, DMSO/TBAF its usefulness for derivatization reactions including the etherification with sodium monochloroacetate and the acylation with vinyl esters of carbonic acids was studied. The Structural features of the products were analyzed by means of H-1 NMR spectroscopy (after depolymerization or peresterification). C-13 NMR spectroscopy, and HPLC after complete hydrolytic chain degradation. The results Were compared With those obtained from derivatives prepared using the solvent N,N-dimethylacetamide (DMAc)/LiCl and conventional, heterogeneous synthesis. It can be shown that in case of carboxymethylation reactions the reaction medium applied has a drastic influence both on the course of reaction and on the structural features of the products. A highly efficient tool was found to be atomic force microscopy (AFM), showing remarkable differences in the superstructures of the differentially synthesized derivatives.