A novel liquid crystalline polymer—hydmxyethyl chitosan(HECS) was synthesized in alkali system．The degree of molar etherification(DME) of HECS was controlled by both the amounts of ethylene oxide and the reaction time．DME of HECS specimens was from 0.2 to 5.4 measu~d by element analysis and NMR．All specimens formed typical cholesteric texture—fingerprint texture while dissolved in formic acid．HECS with DME>1.9 was water soluble．and the HECS aqueous solution also formed eholesterie phase with typical texture．The mesophase texture was detected both by polarized optical microscopy and scanning electron microscopy．Samples for SEM studies were treated by permanganic etching in order to increase the contrast．The studies were focused on the effect of DME on the eritical concentration(C*) of mesophase formation for HECS／formic acid solutions．The results indicated that c* sharply increased with DME at first．and became independent as SDME variedfrom 0.2 to 1.9．Mterthat(DME>1.9)

it regain obvious rise as DME continuously heightened．These results were explained by the variation of both persistencelength q andmoleculardiameter d in Flory’s semi-experience equation c*≈8q／x(x=2q／d)．The variation of DME of HECS related with two structural factors．i．e．the Rumbet and Iength of the substituent．the former affected c* slightly

hut the latter affected c* evidently．