Methanesulfonic acid method was used to synthesize five acylated chitosans

i.e.acetyl chitosan

propionyl chitosan

butyryl chitosan

hexanoyl chitosan and heptanoyl chitosan.All derivatives demonstrated lyotropic liquid crystalline behavior.Cholesteric phase was shown by the presence of fingerprint textures.Substitution degree of propionyl chitosan in the range from 0.21 to 0.94 had no obvious effect on the critical concentration

because a small substitution degree such as 0.21 is large enough to destroy most of the hydrogen band of inter-and-intra-molecules.But the critical concentration(W/W)increased form 0.15 to 0.22

as the side chain length increased. This phenomenon can be explained by the drop of the rigidity of the chain. Typical droplet texture appeared in the biphase coexistence concentration region of all five acylated chitosans.The transition concentration from biphase coexistence to mesophase was also affected by the side chain length.Acylated chitosans were all water soluble and exhibited lyotropic liquid crystalline behavior in water.