Synthesis, Characterization, and Swelling Kinetics of Carboxymethyl Cellulose Grafted Polyacrylic Acid Hydrogels

International Journal of Chemistry | Vol. 3, No. 5, May 2012 | pp. 34–41

DOI: 10.46882/2012/IJC/000044

Article Type: Original Research Paper

Title: Synthesis, Characterization, and Swelling Kinetics of Carboxymethyl Cellulose Grafted Polyacrylic Acid Hydrogels

Names of Authors: J. K. Mensah¹, M. A. Idowu²*

Authors’ Affiliations:
¹Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
²Department of Environmental Management, Federal University of Agriculture, Abeokuta, Nigeria.

Abstract: Smart polymeric hydrogels that respond to environmental changes find valuable applications in controlled drug delivery and agricultural soil hydration. This study describes the synthesis and swelling optimization of a biodegradable hydrogel prepared via the graft copolymerization of acrylic acid (AA) onto a carboxymethyl cellulose (CMC) backbone. The reaction was performed in an aqueous medium using potassium persulfate (KPS) as a free-radical initiator and N,N'-methylenebisacrylamide (MBA) as a crosslinker. The structural configuration of the CMC-g-PAA hydrogel was confirmed using Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Swelling kinetics were evaluated as a function of time, solution pH (2.0 to 12.0), and external salt concentrations. The hydrogel exhibited highly sensitive pH-dependent swelling behavior, showing maximum water absorption capacity (420 g/g) at pH 7.4 due to the complete ionization and electrostatic repulsion of carboxylate anions. Conversely, swelling was strongly suppressed in highly acidic media and in the presence of multivalent cations (Al³⁺ and Ca²⁺). Kinetic modeling confirmed that the water diffusion process followed a second-order swelling model, establishing its suitability for moisture retention matrices.

Keywords: Carboxymethyl cellulose; Acrylic acid; Graft copolymerization; Hydrogel; pH-sensitive swelling; Kinetic modeling

Manuscript Timeline: Received: July 15, 2011; Revised: August 28, 2011; Accepted: September 18, 2011; Published: May 04, 2012.

Citation: Mensah, J. K., & Idowu, M. A. (2012). Synthesis, Characterization, and Swelling Kinetics of Carboxymethyl Cellulose Grafted Polyacrylic Acid Hydrogels. International Journal of Chemistry, 3(5), 34–41.

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