Arai Kengo, Horikawa Yoshiki, Shikata Toshiyuki, Iwase Hiroki
Department of Symbiotic Science of Environment and Natural Resources, The United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology 3-5-8 Saiwai-cho Fuchu Tokyo 183-8509 Japan
Cellulose Research Unit, Tokyo University of Agriculture and Technology 3-5-8 Saiwai-cho Fuchu Tokyo 183-8509 Japan.
RSC Adv. 2020 May 19;10(32):19059-19066. doi: 10.1039/d0ra03437a. eCollection 2020 May 14.
The structure and conformation of methyl cellulose (MC) and hydroxypropyl methyl cellulose (HpMC) ether samples dissolved in dilute aqueous (DO) solutions at a temperature of 25 °C were reconsidered in detail based on the experimental results obtained using small- and wide-angle neutron scattering (S-WANS) techniques in a range of scattering vectors () from 0.05 to 100 nm. MC samples exhibited an average degree of substitution (DS) by methyl groups per glucose unit of DS = 1.8 and the weight average molar mass of = 37 × 10 and 79 × 10 g mol. On the other hand, HpMC samples possessed the average molar substitution number (MS) by hydroxypropyl groups per glucose unit of MS = 0.25, DS = 1.9, and = 50 × 10 and 71 × 10 g mol. The concentration-reduced scattering intensity data gathered into a curve for the solutions of identical sample species clearly demonstrated the relationship () ∝ in a range from 0.05 to 2.0 nm, and small interference peaks were found at ∼ 7 and 17 nm for all examined sample solutions. These observations strongly revealed that form factors for both the MC and HpMC samples were perfectly described with that for long, rigid rod particles with average diameters of 0.8 and 0.9 nm, respectively, and with an inner structure with characteristic mean spacing distances of 0.9 and 0.37 nm, respectively, regardless of the chemically modified conditions and molar masses. A rationally speculated structure model for the MC and HpMC samples dissolved in aqueous solution was proposed.
基于在0.05至100 nm的一系列散射矢量（）范围内使用小角和广角中子散射（S-WANS）技术获得的实验结果，详细重新考虑了在25°C温度下溶解于稀水溶液（DO）中的甲基纤维素（MC）和羟丙基甲基纤维素（HpMC）醚样品的结构和构象。MC样品的每个葡萄糖单元的甲基平均取代度（DS）为DS = 1.8，重均摩尔质量为 = 37×10和79×10 g/mol。另一方面，HpMC样品的每个葡萄糖单元的羟丙基平均摩尔取代数（MS）为MS = 0.25，DS = 1.9， = 50×10和71×10 g/mol。相同样品种类溶液的浓度降低散射强度数据汇聚成一条曲线，清楚地表明在0.05至2.0 nm范围内（）∝，并且在所有检测的样品溶液中，在 ∼ 7和17 nm处发现了小的干涉峰。这些观察结果强烈表明，MC和HpMC样品的形状因子分别用平均直径为0.8和0.9 nm的长刚性棒状颗粒以及内部结构具有特征平均间距分别为0.9和0.37 nm的形状因子完美描述，而与化学改性条件和摩尔质量无关。提出了溶解在水溶液中的MC和HpMC样品的合理推测结构模型。
