A re-investigation of the Mark–Houwink–Sakurada parameters for cellulose in Cuen: A study based on size-exclusion chromatography combined with multi-angle light scattering and viscometry

• Published in: Journal of Chromatography A 2013-03, Vol.1281, p.32-37
• Main Authors: Kes, Mürşide, Christensen, Bjørn E.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Applied sciences; Cellulose; Chemistry; Chromatographic methods and physical methods associated with chromatography; Cuen; equations; Exact sciences and technology; gel chromatography; hydrolysis; light scattering; lithium chloride; MHS equation; Organic polymers; Other chromatographic methods; Physicochemistry of polymers; Properties and characterization; refractive index; SEC-MALLS; solvents; Specific refractive index increment; Structure, morphology and analysis; viscometry; viscosity; Viscosity average DP
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2013.01.038

► Re-assessment of the MHS relation for cellulose in Cuen. ► Degradation correction of intrinsic viscosity in Cuen. ► Molecular weight distribution by SEC-MALLS in 0.5% DMAC/LiCl. ► DPn, DPw and properly defined DPv determined. ► (dn/dc)μ determined. The MHS parameters for cellulose in Cuen (0.5M) were calculated by determining the weight (DPw), number (DPn), and the viscosity average (DPv) of partially hydrolysed celluloses using SEC-MALLS in DMAc containing 0.5% LiCl, combined with intrinsic viscosity measurements in Cuen. The modified MHS equation is: η=2.45DPv0.70=0.070Mv0.70. Application of the equation provides the true viscosity average DP (DPv) for any type of distribution. In contrast, the apparent ‘DPv’ referred to in standard methods (ASTM, SCAN) is an undefined type of average DP which depends on the chain length distribution, and may differ considerably from both DPv and DPw. The DP values obtained by SEC-MALLS depend on the quality of the data, in particular the specific refractive index increment at constant chemical potential (dn/dc)μ, which was found to be 0.117ml/g (at λ0=633nm). Further analysis of the SEC-MALLS and viscometry data in terms of the wormlike chain model provided estimates of the persistence length, obtaining 4.7nm in Cuen and 8.2nm in 0.5% DMAc/LiCl, illustrating the more expanded structure in the latter solvent.