Properties of polyacrylamide composites reinforced by cellulose nanocrystals

Marina I Voronova; Oleg V Surov; Andrei V Afineevskii; Anatoly G Zakharov

doi:10.1016/j.heliyon.2020.e05529

Properties of polyacrylamide composites reinforced by cellulose nanocrystals

Heliyon. 2020 Nov 18;6(11):e05529. doi: 10.1016/j.heliyon.2020.e05529. eCollection 2020 Nov.

Authors

Marina I Voronova¹, Oleg V Surov¹, Andrei V Afineevskii², Anatoly G Zakharov¹

Affiliations

¹ Laboratory of Physical Chemistry of Polymer-Liquid Heterogeneous Systems, G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, 1 Akademicheskaya St., Ivanovo 153045, Russian Federation.
² Department of Physical and Colloid Chemistry, Ivanovo State University of Chemistry and Technology, 7 Sheremetevsky Prospekt, Ivanovo 153000, Russian Federation.

Abstract

In this work, a series of polyacrylamide/cellulose nanocrystal (PAM/CNC) composites with a wide range of compositions were prepared by a solution casting method. Subsequently, the influence of the PAM conformation on the behaviour of the PAM/CNC composites was studied. The microstructural, thermal, and mechanical properties of the PAM/CNC composites were also investigated, as well as their flocculation and dispersion behaviour. Thermal degradation of both CNC and PAM in the composites occurred simultaneously, at a much higher temperature than the degradation of the neat CNC. By TEM and SEM, PAM globule aggregates in the PAM/CNC composites were detected. With an increase in the medium acidity, the PAM globule aggregate size of in the composites decreased. Moreover, the composite films cast from high pH solutions (extended PAM conformation) exhibited superior strength properties than those cast from low pH solutions (contracted coil PAM conformation). The PAM globule conformation provided good re-dispersibility of the freeze-dried PAM/CNC composites by preventing aggregation of the CNC particles. The PAM globule adsorption onto the CNC particles caused CNC surface hydrophobization and a decrease in their surface charge, while maintaining high colloidal stability of the CNC suspensions. Furthermore, the CNC particles with adsorbed PAM were demonstrated to be useful as emulsifiers and compatibilisers.

Keywords: Cellulose nanocrystals; Materials science; Nanotechnology; Polyacrylamide; Polymer composites; Structure-property relationships.