the same case, its alkyl derivatives have clear melting
points.18 This suggests that chitosan has a more rigid
structure than cellulose, which is supported by the fact
that the persistence length of chitosan of 22 nm is much
greater than that of cellulose (11 nm) in LiCl
(5%) + N,N-dimethylacetamide mix solution.19 When
chitosan was grafted with polylactide, its original integrity
was also destroyed. The hydrogen bonds that
existed in it were broken to a certain extent, which
makes intermolecular interactions decrease. On the
other hand, the ester bond is more flexible than that of a
hydrocarbon. When it is used as the branched chain of
chitosan, it can plasticize internally the rigid main chain
of chitosan. Meanwhile, the branched ester linkage is
more polar than that of a hydrocarbon, so there is a
stronger repulsive force among molecules of the branched
ester than that existing among hydrocarbons,
which can be in favor of chitosan retaining its spatial
configuration.