Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 1, pp. 120−127.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © A.B. Shipovskaya, V.I. Fomina, N.A. Solonina, K.A. Yusupova, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 1,
AND POLYMERIC MATERIALS
Preparation of Water-Soluble Chitosan Derivatives
by Modiﬁ cation of the Polymer in Vapors of Monobasic Acids
A. B. Shipovskaya, V. I. Fomina, N. A. Solonina, and K. A. Yusupova
Chernyshevsky Saratov State University, State Educational Institution of Higher Professional Education, Saratov, Russia
Received February 11, 2011
Abstract—Sorption of vapors of monobasic acids and of vapors over their solutions of various concentrations by
high-molecular-weight chitosan was studied. The dependence of the degree of the vapor sorption by the polymer
on the acid solution concentration, chitosan molecular weight, and sorption temperature was determined. Water-
soluble chitosan derivatives were obtained. The hydrodynamic properties of aqueous solutions of the modiﬁ ed
samples were examined.
Chitosan, a biologically active polymer, is widely
used today in the development of multipurpose
pharmaceutical forms (powder, gel, capsules, ﬁ lms,
sponges) for use as wound coatings, biomatrices, and
containers for the delivery of drugs to the intended
localization site. As a rule, water-insoluble chitosan
samples are used for these purposes, which restricts
the polymer application ﬁ eld and complicates the
The solubility of chitosan in water depends on its
molecular weight M
and degree of deacetylation DD.
= 2–16 kDa) and low-molecular-
weight fractions (M
≤ 25 kDa, DD ≥ 70 mol %) of
chitosan are soluble in neutral media . These samples
are prepared by deep depolymerization of chitosan
macromolecules as a result of oxidative, acid, and
enzymatic degradation [2–5].
The molecular weight of the initial chitosan recovered
from crustacean shell chitin can reach 1000 kDa. Such
polymer is insoluble in water and shows only limited
swelling. The following approaches are used to prepare
water-soluble derivatives of high-molecular-weight
The most facile route to water-soluble chitosan
derivatives is dissolution of the polymer in inorganic or
organic acids and isolation of the polymeric salt from the
solution [6–10]. Chitosan salts with monobasic inorganic
and monocarboxylic acids are well soluble in water .
The solubility of the salt form of chitosan in aqueous
medium depends on the procedure and conditions for
the salt isolation from the solution [6, 10]. In addition,
the solubility of chitosan salts in water depends on pK
and structure of the acid. In some cases, to obtain the
salt form, the initial chitosan should be preliminarily
activated in a cavitation or shear ﬁ eld [7, 9].
The chitosan solubility in water can also be improved
by developing formulations or polyelectrolytic
complexes of chitosan with natural or synthetic polymers
Polymer-analogous transformations are also widely
used for preparing water-soluble N- and О-substituted
chitosan derivatives [14–17]. Of particular interest is
graft copolymerization [18–20]. By varying the structure
and type of grafted pendant chains, it is possible to
prepare water-soluble chitosan derivatives not only with
preset properties, but also with new functions.
To prepare water-soluble chitosan derivatives,
we used in this study a new approach: imparting new
properties to a polymer by treating it with vapors of
appropriate solvents. This approach was successfully
tested with vegetable polysaccharides, cellulose esters
[21, 22]. It consists in modiﬁ cation of a polymer with