Dilute solution properties of cellulose in LiOH/urea aqueous system

✍ Scribed by Jie Cai; Yating Liu; Lina Zhang

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 287 KB
• Volume: 44
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/polb.20938

✦ Synopsis

Abstract

Cellulose was dissolved rapidly in 4.6 wt % LiOH/15 wt % urea aqueous solution and precooled to –10 °C to create a colorless transparent solution. ^13^C‐NMR spectrum proved that it is a direct solvent for cellulose rather than a derivative aqueous solution system. The result from transmission electron microscope showed a good dispersion of the cellulose molecules in the dilute solution at molecular level. Weight‐average molecular weight (M~w~), root mean square radius of gyration (〈s^2^〉~z~^1/2^), and intrinsic viscosity ([η]) of cellulose in LiOH/urea aqueous solution were examined with laser light scattering and viscometry. The Mark–Houwink equation for cellulose in 4.6 wt % LiOH/15 wt % urea aqueous solution was established to be [η] = 3.72 × 10^−2^ M in the M~w~ region from 2.7 × 10^4^ to 4.12 × 10^5^. The persistence length (q), molar mass per unit contour length (M~L~), and characteristic ratio (C~∞~) of cellulose in the dilute solution were given as 6.1 nm, 358 nm^−1^, and 20.8, respectively. The experimental data of the molecular parameters of cellulose agreed with the Yamakawa–Fujii theory of the worm‐like chain, indicating that the LiOH/urea aqueous solution was a desirable solvent system of cellulose. The results revealed that the cellulose exists as semistiff‐chains in the LiOH/urea aqueous solution. The cellulose solution was stable during measurement and storage stage. This work provided a new colorless, easy‐to‐prepare, and nontoxic solvent system that can be used with facilities to investigate the chain conformation and molecular weight of cellulose. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3093–3101, 2006