This study was conducted in order to develop novel chitosan/poly(ethylene
oxide)(PEO) blend films crosslinked by genipin as potential membranes for potential
medical applications, such as controlled drug carriers and separation of proteins from
eleutherococcuss enticosus (ES).
Genipin, a naturally occurring and non-toxic crosslinking reagent, was used to form
chitosan and chitosan/PEO blend networks. Genipin is found in traditional Chinese
medicine and extracted from Gardenia fruit. Importantly,it overcomes the problem of
physiological toxicity inherent in the use of common synthetic chemicals as
The miscibility and morphology of chitosan /PEO blends were examined by means of
differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy
(FT-IR) and small angle X-ray scattering (SAXS). The experimental results indicate
that the chitosan/PEO blends are miscible over the whole composition range. A
phenomenon was observed for chitosan/LPEO (lower molecular weight PEO) blends:
when the composition of chitosan was less than 60% by weight, the melting points
increased as the composition of chitosan was increased. It is believed that there are
strong molecular interactions between chitosan molecules and the molecules in the
crystalline phase of LPEO in the chitosan ALPEO blends.
FT-IR and UV spectra analysis of the crosslinking reaction of chitosan revealed that
the hydroxyl groups (3400 cm-1) and the amide groups (1645 cm-) in chitosan
participated actively in the reaction. SAXS results showed that a heterogeneous
structure exists in the chitosan/HPEO (or /LPEO) blend networks. Crosslinking by
genipin restricts crystallisation and leads to smaller crystals.
The mechanical properties, the stability in water, the swelling behaviour and
surface properties of the films were also investigated. (Continues...).
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.