1070-4272/05/7809-1486+2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 9, 2005, pp. 1486 !1488. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 9,
2005, pp. 1511!1513.
Original Russian Text Copyright + 2005 by Kulish, Kolesov.
AND POLYMERIC MATERIALS
A Study of Structure Formation in Chitosan!Polyvinyl Alcohol
Blends by Turbidity Spectroscopy
E. I. Kulish and S. V. Kolesov
Bashkir State University, Ufa, Bashkortostan, Russia
Received March 21, 2005
Abstract-The structure formation of film samples of chitosan, polyvinyl alcohol, and their blends was
studied by turbidity spectroscopy.
A blend of water-soluble polymers, polyvinyl al-
cohol (PVA) and aminopolysacharide, chitosan (CS),
shows promise for preparing films and fibers combin-
ing high strength, biodegradability, and high hydro-
philicity . Introduction of PVA into CS, which is
characterized by physiological activity, increases the
flexibility of fairly brittle chitosan films . Film
materials based on PVA are widely used as mem-
branes, artificial leather, and packing. Chitosan is used
for reinforcing PVA films. Many properties of the
polymeric composition are set in the stage of its for-
mation and are determined by the phase and supra-
molecular structure of the polymer blend. The pos-
sibility of controlling the structure and properties of
polymeric films, on the one hand, and unique proper-
ties of CS, on the other hand, give grounds to expect
that polymeric films based on PVA and chitosan can
serve as polymeric support for systems with control-
lable release of a drug.
In this study, we examined the structure of film
samples of PVA and CS blends prepared from the
combined solution and the principal possibility of
release of a drug (gentamicin) from such films.
PVA of 16/1 grade [GOST (State Standard) 107793
78)] with M
= 25000, CS sample [TU (Technical
Specification) 6-09-05-296376] prepared by base de-
acetylation of crab chitin (degree of deacetylation
= 120000), and gentamicin antibiotic were
used without additional purification. Films of the in-
dividual polymers and their blends were prepared by
casting the initial solutions onto the glass surface.
The polymer concentration was varied from 0.2 to
. The solvent quality with respect to CS was
controlled by varying the solution acidity [dissolution
of CS in 5% aqueous ultrapure grade acetic acid (here-
inafter these solutions are denoted as 5-AA) or
1% acetic acid (1-AA)]. To determine the average
dimensions of supramolecular particles r and their
number N in 1 cm
in the films, we used turbidity
spectroscopy [3, 4]. The measurements were per-
formed within l = 3403590 nm at 20oC on a KFK-
2MP photocolorimeter. The kinetics of gentamicin
release from films placed in alkaline solution (pH 10)
to prevent dissolution of CS was studied spectropho-
tometrically at l = 240 nm (the absorption band of the
pentosan ring of gentamicin) on a UV-VIS Specord
M-40 spectrophotometer. The gentamicin content in
the film was 2 wt %.
The study of PVA and CS films showed that the
average turbidity of the films prepared from dilute
solutions is substantially higher than that of the films
prepared from more concentrated solutions (Fig. 1).
Figure 2 shows that, with increasing concentration of
the initial solution, the dimensions of supramolecular
particles decrease and their number increases. This
non-trivial result can be explained as follows. Forma-
Fig. 1. Average turbidity J
of (1, 2) CS and (3) PVA
films as a function of the polymer concentration c in the
initial solution in (1) 5-AA and (2, 3) 1-AA.