e-Polymers 2003, no. 033. ISSN 1618-7229 http://www.e-polymers.org Novel polyelectrolyte complex between chitosan and poly(2-acryloylamido-2-methylpropanesulfonic acid-co- acrylic acid) Dilyana Paneva, Olya Stoilova, Nevena Manolova *, Iliya Rashkov Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Sofia 1113, Acad. G. Bonchev Str. bl. 103 A, Bulgaria; Fax +359 2 8707 523; manolova@polymer.bas.bg (Received: June 5, 2003; published: July 1, 2003) Abstract: A novel polyelectrolyte complex between chitosan and copolymers of 2- acryloylamido-2-methylpropanesulfonic acid (AMPS) and acrylic acid (AA) has been prepared. The formation of the complex has been studied viscometrically, gravimetrically and turbidimetrically in the pH range from 1.2 to 5.8. The stoichio- metry and the yield of the complex depend on the copolymer composition and on the pH value of the medium. In the case of copolymers with low content of AMPS units the complexes are enriched in copolymer when formed in the pH range from 1.2 to 4.8. In this pH region mainly AMPS units take part in complex formation. A stoichiometric complex forms only at higher pH values due to the increased number of complexable carboxylate ions of AA units. The stoichiometry of the complexes prepared from copolymers with higher content of AMPS units is close to equimolar and is less sensitive to pH. The obtained complexes are stable up to pH 8. It has been shown that chitosan once included in the complexes remains degra- dable under the action of a crude enzyme complex produced by the soil fungus Trichoderma viride. The rate of the enzymatic hydrolysis decreases in the order chitosan/PAA > chitosan/P(AMPS-co-AA) > chitosan/PAMPS. Tests on the proli- feration of T. viride embedded in chitosan beads have shown that coating the beads with chitosan/P(AMPS-co-AA) complex does not hamper the development of the microorganisms. Introduction The preparation of polyelectrolyte complexes (PECs) of chitosan by mixing polymer solutions is a simple and convenient way for creating new polymer materials that might be used in agriculture and medicine. Thus, chitosan properties are combined with those of suitable synthetic polymers opening new prospects for its utilisation and valorisation as a polymer from renewable resources. Complexes based on chitosan are well known in the field of biomaterials, owing to their possible application for the immobilisation of enzymes, microencapsulation of cells, and for the design of drug release devices [1-3]. Complex formation between chitosan and polyacrylic acid (PAA) has been investigated by several groups [4-10]. The composition of the complexes chitosan/PAA depends on the pH value of the medium and a water- insoluble complex is formed in a narrow pH range – from 3 to 6 [10]. Previously, we have studied the PEC between chitosan and poly(2-acryloylamido-2-methylpropane- 1 Unauthenticated Download Date | 4/12/16 3:49 AM