NOBIPOL, Department of Biotechnology, NTNU Norwegian University of Science and Technology, Sem Saelands vei 6/8, NO-7491, Trondheim, Norway.
J Chromatogr A. 2013 Mar 15;1281:32-7. doi: 10.1016/j.chroma.2013.01.038. Epub 2013 Jan 25.
The MHS parameters for cellulose in Cuen (0.5 M) were calculated by determining the weight (DP(w)), number (DP(n)), and the viscosity average (DP(v)) 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=2.45DP(v)(0.70)=0.070 M(v)(0.70). Application of the equation provides the true viscosity average DP (DP(v)) for any type of distribution. In contrast, the apparent 'DP(v)' 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 DP(v) and DP(w). 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 0.117 ml/g (at λ(0)=633 nm). Further analysis of the SEC-MALLS and viscometry data in terms of the wormlike chain model provided estimates of the persistence length, obtaining 4.7 nm in Cuen and 8.2 nm in 0.5% DMAc/LiCl, illustrating the more expanded structure in the latter solvent.
采用 SEC-MALLS 在含有 0.5%LiCl 的 DMAc 中测定部分水解纤维素的重均分子量 (DP(w))、数均分子量 (DP(n)) 和黏均分子量 (DP(v))，结合在 Cuen 中的特性黏度测量值，计算纤维素在 Cuen (0.5 M) 中的 MHS 参数。改进的 MHS 方程为：η=2.45DP(v)(0.70)=0.070 M(v)(0.70)。该方程的应用为任何类型的分布提供了真实的黏均分子量 DP（DP(v)）。相比之下，标准方法（ASTM、SCAN）中提到的表观“DP(v)”是一种未定义的平均 DP 类型，它取决于链长分布，并且可能与 DP(v)和 DP(w)有很大差异。SEC-MALLS 获得的 DP 值取决于数据的质量，特别是在恒定化学势下的比折光指数增量（dn/dc）(μ)，其值为 0.117 ml/g（λ(0)=633nm）。根据蠕虫链模型对 SEC-MALLS 和黏度数据进行进一步分析，得到了持久长度的估计值，在 Cuen 中为 4.7nm，在 0.5%DMAc/LiCl 中为 8.2nm，说明在后一种溶剂中结构更为扩展。
