Abstract:
Polyelectrolytes are one of the dominant materials from the beginning of life on this planet. This fact is exemplified by replicating charged polyelectrolyte (RNA, DNA) that contain information. Applications of polyelectrolytes range from colloidal stabilization, flocculation and flow modification to superabsorbent gels. For the importance and ubiquity of polyelectrolytes in both artificial and biological system, investigation of different properties of polyelectrolytes is now a recent trend for both academic and industry. Among them polysaccharides based polyelectrolytes have special demand due to their structural importance. The most abundant polysaccharide available today worldwide is cellulose, which a linear β-1,4-D-glucan. Cellulose-based polyelectrolytes, such as carboxymethyl cellulose (CMC) and cellulose-grafted copolymers, have been widely investigated. As cellulose has an advantage having high degree of functionality, chemical modification of abundant hydroxyl groups of cellulose is popular route to make this natural polymer more attractive. However, most of the chemical modification has been done on C-6 position. There is also scope of modification other than C-6.
In the present study a possible route to prepare a novel polyelectrolyte based on modified nano cellulose has been described. The modification was done on glucose moiety of cellulose by cleaving the C-2 and C-3 bond through selective oxidation using sodium meta-periodate,where the vicinal hydroxyl groups were converted to aldehyde groups. This di-aldehydic group containing cellulose chain was further oxidized to di-carboxylic acid group by sodium chloride, sodium chlorite and hydrogen peroxide. Due to the presence of large number of carboxylic group in the nano cellulose chain, the material acts as a polyelectrolyte.
The aldehyde and carboxyl content was calculated from the oxime formation and conductometric titration, respectively. The conversion was ensured with the help of FTIR and different chemical tests. The crystallinity and surface morphology was revealed by FESEM and XRD analysis, respectively. The polyelectrolyte nature of the material was carried out with a custom designed ion exchange system where water uptake capacity was shown by change in hydro-dynamic radius calculated from the experimental data of Dynamic Light Scatterign measurement. The possible ion exchange mechanism was confirmed as a function of water uptake capacity by measuring the conductivity. The water uptake tendency was observed in different ionic strength of solvent. The materials was shown as biocompatible by the negative control in microbial limit test.
Thus this prepared material is envisioned to be well established for the application in various areas such as the petrochemical, cosmetics, paint industries, water treatment and controlled drug release.
