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An efficient five-step synthetic route was developed for full N-substitution of chitosan with a quaternary betaine moiety. The developed synthetic procedure can also be controlled to produce chitosan N-betainates having lesser degrees of substitution. 6-O-Triphenylmethylchitosan, which is highly soluble in organic solvents, was used as an intermediate for N-acylation reactions. Intermediate products were characterized by 13 C CP/MAS NMR, FT-IR, and elemental analysis. The water-soluble quaternary chitosan N-betainates were thoroughly characterized by 1 H NMR and 13 C NMR and by 2D 1 H-1 H COSY NMR and 13 H-1 H HSQC NMR. Degrees of substitution were determined from the 1 H NMR spectra. A significant degradation of the polysaccharide backbone during the synthetic procedure was determined by GPC with a light scattering detector. Experimental SectionMaterials. Chitosan, used as a starting material, was donated by Primex ehf (Reykjavik, Iceland). Weight-average molar mass (Mw) 148 200 Da and number-average molar mass (Mn) 94 200 were determined by GPC-LS. The degree of deacetylation (85%) was confirmed by 1 H NMR. All other chemicals used were commercially available and used as received. Pyridine was distilled over KOH. Dialysis membrane (M w cutoff 12 kDa) was purchased from Sigma (St. Louis, MO).Characterization. 1 H and 13 C spectra were recorded on a Bruker AVANCE DRX 500, operating at 500.13 and 125.76 MHz, respectively. Samples of chitosan N-betainates (40 mg) were dissolved in 600 µL of D 2O. Chemical shifts (δ) are

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