Characterization of cellulose–chitosan gels prepared using a LiOH/urea aqueous solution

• Published in: Cellulose (London) 2019-07, Vol.26 (10), p.6189-6199
• Main Authors: Kim, Ung-Jin, Kimura, Satoshi, Wada, Masahisa
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Bioorganic Chemistry; Butanol; Cellulose; Ceramics; Chemistry; Chemistry and Materials Science; Chitosan; Composites; Ethanol; Freeze drying; Gels; Glass; Hydrogels; Natural Materials; Organic Chemistry; Original Research; Physical Chemistry; Polymer Sciences; Pore size; Porosity; Protonation; Regeneration; Sustainable Development; Swelling ratio; Ureas
• ISSN: 0969-0239; 1572-882X
• DOI: 10.1007/s10570-019-02527-5

Cellulose–chitosan gels were prepared using a LiOH/urea aqueous solution for a co-dissolution. After cellulose and chitosan were dissolved by a freeze–thaw process, the hydrogels were prepared via regeneration in methanol and washing with water. Finally, freeze-dried cellulose–chitosan gels were obtained via solvent exchange (water → ethanol →  t -butyl alcohol) followed by freeze-drying. The chitosan contents of the gels were determined by the amino and nitrogen contents, confirming formation at the blend ratio of cellulose and chitosan. Structural and thermal analyses showed that the data profiles were proportional to the content of each component. Although all gels exhibited a three-dimensional porous structure, the introduction of chitosan remarkably increased pore size, resulting in lower transmittance of the hydrogels. The surface area of the cellulose–chitosan gels increased from 247 to 337 m 2 /g, and the swelling ratio gradually improved with an increase in chitosan content, especially up to 22.9 g/g at pH 5 due to protonation of amino groups. The increase in chitosan content significantly reduced the mechanical strength, while the adsorption capacity of anionic dye was greatly enhanced.