BACKGROUND: The aim of the present work was to improve the properties of acrylic polymer, which is a major fibre-forming polymer. Acrylonitrile/acrylic acid copolymer, P(AN/AA), was chosen for this purpose and it was intended to study the condition for the formation of hydroxyl groups through the formation of hyperbranched polymers. RESULTS:The synthesis of a dendritic polymer of citric acid (CA) in the solid phase on a P(AN/AA) core is described. The product was analysed using the elemental analysis technique and 1 H NMR. Dendritic molecules were grown by a reaction between the carboxylic acid of acrylic acid and hydroxyl group of CA activated by dicyclohexylcarbodiimide. Products were analysed using Fourier transform infrared and NMR spectroscopy. CONCLUSION:The formation of CA dendrigraft on P(AN/AA) films in a heterogeneous system is possible. The percentage conversion of the copolymer reaction with CA was calculated based on the NMR results. The percentage conversion showed a gradual reduction with an increase in step numbers. The contact angle of water on the films was affected by the percentage conversion of the reactions. A calculation scheme is presented to show that the low degree of conversion leads to an increase in hydrophobic groups.

Samples of film, wet-and electro-spun fibers and powder were prepared from acrylonitrile/acrylic acid copolymer, with their specific surface areas being considerably different. We attempted to alter the properties of the samples by increasing the amount of carboxylic acid groups on the surfaces through the formation of dendritic structures. Dendritic molecules were grown by a reaction between the carboxylic acid groups of acrylic acid, activated by dicyclohexylcarbodiimide, and hydroxyl groups of citric acid. Products were analyzed using Fourier transform infrared and NMR spectroscopy, optical microscopy, scanning electron microscopy and density measurements. It was found that with an increase of the specific surface area, the percentage conversion increased indicating that the topochemical reactions were prominent. The density of electro-spun fibers was the greatest indicating the most compact structure. With an increase of step numbers of dendrigraft formation the density reached a minimum which points to the formation of nanoscale voids in the deposited dendritic structure.