Polyelectrolyte complexes obtained by radical polymerization in the presence of chitosan

Abstract

The radical polymerization of acrylic acid and sodium 4-styrenesulfonate in the presence of chitosan as a template gives insoluble products, identified as the polyelectrolyte complexes chitosan-poly(acrylic acid) and chitosan-poly(4-styrenesulfonate). Kinetic results do not permit to propose any mechanism in the first case, while suggest a ''pickup'' one in the second. The polyelectrolyte complexes have been characterized by FT-IR spectroscopy, X-ray diffractometry, optical and scanning electron microscopies, differential scanning calorimetry and thermogravimetric analysis. The results obtained indicate an ordered structure for the first complex, while the second one appears similar to that obtained by reacting the parent polymers. Therefore, the template polymerization technique appears advantageous only for the synthesis of the chitosan-poly(acrylic acid) complex. The thermal analysis shows that the complexes undergo two successive modifications on heating. FT-IR analysis demonstrates that the first process is an esterification between the hydroxyls of chitosan and the acidic groups of both daughter polymers; the second one appears to be an amidation of the chitosan ammonium groups only with the sulfonate groups

Novel polyelectrolyte complex between chitosan and poly(2-acryloylamido-2-methylpropanesulfonic acid-coacrylic acid)

“…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][2][3]. Complex formation between chitosan and polyacrylic acid (PAA) has been investigated by several groups [4][5][6][7][8][9][10]. The composition of the complexes chitosan/PAA depends on the pH value of the medium and a waterinsoluble complex is formed in a narrow pH range -from 3 to 6 [10].…”

Biomimetic Tailoring of the Surface Properties of Polymers at the Nanoscale: Medical Applications

“…The very general concept of this process, inspired by the natural routes to nucleic acids and proteins as in the basics of the Central Dogma of Synthetic Biology is to use a template directed synthesis of macromolecules from their monomers [141][142][143][144] involving the molecular recognition, ligation, and product dissociation steps [145]. By using template polymerization of synthetic monomers onto biological templates, bioartificial polymeric blends with a higher degree of miscibility between the two components than by simple mixing of pre-formed polymers are obtained [146,147]. However, a true biomimetic behaviour of these bioartificial materials has been not fully demonstrated, yet.…”

The relevance of the transfer of molecular information between natural and synthetic materials in the realisation of biomedical devices with enhanced properties

“…Hydrogen bonding is one of the main interactions involved in the realisation of such materials. For example, while the presence of chitosan showed to poorly affect the rate of acrylic acid (AA) polymerization, the resulting material had different thermal behaviour and a more ordered structure with respect to the blends prepared from preformed polymers [8].…”