Copolymer of Acrylonitrile/Acrylic Acid Film Dendrigrafted with Citric Acid: Host/Guest Properties of Dendrigraft/Dye Complexes in Relation to Acrylic Acid Content

Host/guest properties of acrylonitrile/acrylic acid copolymer (P(AN/AA)) film with various contents of acrylic acid (AA) were examined on dendrigraft/dye complexes in a divergent synthetic route. The reactions were performed on P(AN/AA) films containing 5, 10 and 20 mol% acrylic acid in feed. The products were analyzed using 1H NMR, FTIR, UV-visible spectroscopy, density determination, acidimetric titration, staining and transfer printing. The results showed that for the films based on three different amounts of acrylic acid, the relatively higher acid content showed a lower rate of conversion due to the reduced steric hindrance. Furthermore, the dyes were used to probe the structure of dendrigraft on the P(AN/AA) film. Staining with methylene blue showed the interaction with the exterior end groups; while printing with disperse dyes as guest molecules may illustrate the effectiveness of the hollow interior spaces. In the trend of dye uptake and density versus generation numbers, the emerging maximum dye uptake and minimum density in the first generation confirmed that a dense shell dendritic structure is being formed. Also, the effects of acrylic acid content and the steps number in dendrigraft structure are explained on the basis of films characteristics with reference to the dendrigraft architecture.