纤维素的超分子结构和物理化学性质对其在氯化锂/N，N-二甲基乙酰胺溶剂体系中溶解性的影响。

Influence of the supramolecular structure and physicochemical properties of cellulose on its dissolution in a lithium chloride/N,N-dimethylacetamide solvent system.

作者信息

Ramos Ludmila A, Assaf José M, El Seoud Omar A, Frollini Elisabete

机构信息

Instituto de Química de São Carlos, Universidade de São Paulo, C P 780, 13 560 970, São Carlos, SP, Brazil.

出版信息

Biomacromolecules. 2005 Sep-Oct;6(5):2638-47. doi: 10.1021/bm0400776.

DOI:10.1021/bm0400776

PMID:16153102

Abstract

The present work deals with the effects of structural variables of celluloses on their dissolution in the solvent system LiCl/N,N-dimethylacetamide, LiCl/DMAc. Celluloses from fast growing sources (sisal and linters), as well as microcrystalline cellulose (avicel PH-101) were studied. The following structural variables were investigated: index of crystallinity, I(c); crystallite size; polymer porosity; and degree of polymerization determined by viscosity, DPv. Mercerization of fibrous celluloses was found to decrease DPv, I(c), the specific surface area, and the ratio pore volume/radius. The relevance of the structural properties of cellulose to its dissolution is discussed. Rate constants and activation parameters of cellulose decrystallization, prior to its solubilization, have been determined under nonisothermal conditions. The kinetic parameters calculated showed that dissolution is accompanied with small, negative enthalpy and a large, negative entropy of activation.

摘要

本研究探讨了纤维素结构变量对其在LiCl/N,N-二甲基乙酰胺（LiCl/DMAc）溶剂体系中溶解的影响。研究了来自快速生长源的纤维素（剑麻和棉短绒）以及微晶纤维素（微晶纤维素PH-101）。研究了以下结构变量：结晶度指数I(c)、微晶尺寸、聚合物孔隙率以及通过粘度测定的聚合度DPv。发现纤维状纤维素的丝光处理会降低DPv、I(c)、比表面积以及孔体积/半径比。讨论了纤维素结构性质与其溶解的相关性。在非等温条件下测定了纤维素溶解前脱结晶的速率常数和活化参数。计算得到的动力学参数表明，溶解伴随着较小的负焓变和较大的负活化熵变。