Abstract

The physicochemical properties of 16 laboratory and 9 commercial samples of cellulose diacetate (CDA) of standard (3 wt%) and high (3.5–40 wt%) humidity, their solutions in acetone and an acetone–water mixture with component ratios of 95:5–99.5:0.5 were studied. Samples were taken at the polymer drying stage after wood pulp acetylation under heterogeneous conditions, followed by saponification in an alkaline medium. It was established that high-humidity CDA differed from the standard sample by an amorphized structure, improved solubility with almost the same numerical values of the size and concentration of supramolecular particles, turbidity, viscosity and viscous flow activation energy. The chiral structure of high-humidity CDA differed significantly from the polymer of standard humidity, which was confirmed by a change in the values and sign (from positive to negative) of the specific optical rotation in solution. Changes in humidity by means of polymer hydration in water or in steam within 20–100 °C, as well as water addition to an acetone solution of standard CDA, almost did not affect the stereomeric organization of the cellulose ester. The following were prepared from the CDA with high humidity and, accordingly, a modified chiral structure: fibers with improved physico-mechanical characteristics; membranes capable of purifying blood plasma from cholesterol while saving proteins and electrolytes; films with high selectivity and hydrodynamic permeability; and filter sorbents with a high degree of retaining the harmful components of tobacco smoke. It has been suggested that obtaining high-humidity CDA can be considered as an alternative method of obtaining acetic cellulose ester with a pregiven chiral structure to manufacture highly efficient materials, including those with novel functional properties.

Graphic abstract

中文翻译：

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获得具有预定手性结构的二乙酸纤维素的方法，用于高效材料

摘要

标准（3 wt％）和高（3.5-40 wt％）湿度的16个实验室样品和9个商业样品的双乙酸纤维素（CDA）的理化性质，它们在丙酮中的溶液以及组分比率为95的丙酮-水混合物： 5-99.5：0.5进行了研究。木浆在非均相条件下乙酰化后，在聚合物干燥阶段取样，然后在碱性介质中进行皂化。可以确定的是，高湿度CDA与标准样品的区别在于其非晶态结构，改善的溶解度，超分子颗粒的大小和浓度，浊度，粘度和粘性流动活化能几乎相同。高湿CDA的手性结构与标准湿度的聚合物明显不同，这可以通过溶液中特定旋光度的值和符号（从正到负）的变化来确认。通过在20–100°C的温度下在水中或蒸汽中进行聚合物水合以及在标准CDA的丙酮溶液中加水来改变湿度，几乎不会影响纤维素酯的立体异构组织。由具有高湿度并因此具有改进的手性结构的CDA制备了以下材料：具有改善的物理机械特性的纤维；能够从胆固醇中净化血浆，同时节省蛋白质和电解质的膜；具有高选择性和流体动力渗透性的薄膜；和过滤器吸附剂，能够高度保留烟草烟雾中的有害成分。

图形摘要