Conformational study on the thermal transition of chitosan-g-poly(N-vinylcaprolactam) in aqueous solution

• Published in: Colloid and polymer science 2016-03, Vol.294 (3), p.555-563
• Main Authors: Fernández-Quiroz, Daniel, González-Gómez, Álvaro, Lizardi-Mendoza, Jaime, Vázquez-Lasa, Blanca, Goycoolea, Francisco M., San Román, Julio, Argüelles-Monal, Waldo M.
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Chitosan; Coiling; Complex Fluids and Microfluidics; Copolymers; Evolution; Food Science; Graft copolymers; Nanotechnology and Microengineering; Original Contribution; Physical Chemistry; Polymer Sciences; Soft and Granular Matter; Solubility; Strength
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s00396-015-3816-0

Conformational changes of the thermal transitions of chitosan- graft -poly( N -vinylcaprolactam) copolymers in aqueous solution were studied by varying of the length of the grafted poly( N- vinylcaprolactam) (PVCL) chains, as well as the ionic strength and the pH of the solution. The conformational properties of the copolymer were monitored by means of dynamic light scattering and ζ-potential measurements. A series of copolymers with defined molecular architecture were synthesized. Obtained results point out that hydrophobic hydration plays a crucial role on the solubility of this copolymer at neutral and slightly alkaline solutions. The evolution of the size of macromolecular aggregates indicates that, in the coil state, there is a monomodal distribution, passing through a bimodal distribution in the pre-transition region, just before the phase separation. The role of the charge of the copolymers on the cooperative transition is also analyzed. The phase transition of these amphiphilic copolymers shows a strong dependence on the ionic strength of the solution.