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Nanoscale Wetting of Crystalline Cellulose
Biomacromolecules ( IF 6.2 ) Pub Date : 2021-09-13 , DOI: 10.1021/acs.biomac.1c00801 Lucas N Trentin 1 , Caroline S Pereira 1 , Rodrigo L Silveira 1, 2 , Stefan Hill 3 , Mathias Sorieul 3 , Munir S Skaf 1
Biomacromolecules ( IF 6.2 ) Pub Date : 2021-09-13 , DOI: 10.1021/acs.biomac.1c00801 Lucas N Trentin 1 , Caroline S Pereira 1 , Rodrigo L Silveira 1, 2 , Stefan Hill 3 , Mathias Sorieul 3 , Munir S Skaf 1
Affiliation
Cellulose possesses considerable potential for a wide range of sustainable applications. Nanocellulose-based material properties are primarily dependent on the structural surface characteristics of its crystalline planes. Experimental measurements of the affinity of crystalline nanocellulose surfaces with water are scarce and challenging to obtain. Therefore, the relative hydrophilicity of different cellulose allomorphs crystalline planes is often inferred from qualitative assessments of their surface and the exposition of polar groups to the solvent. This work investigates the relative hydrophilicity of cellulose surfaces using molecular dynamics simulations. The behavior of a water droplet laid on different crystal planes was used to determine their relative hydrophilicity. The water molecules fully spread onto highly hydrophilic surfaces. However, a water droplet placed on less hydrophilic surfaces equilibrates as an oblate spheroidal cap allowing the measurement of a contact angle. The results indicate that the Iα (010), Iα (11̅0), Iβ (010), and Iβ (110) faces, as well as the faces of human-made celluloses II and III_I (100), (11̅0), (010), and (110) are all highly hydrophilic. They all have a contact angle value inferior to 11°. Not unexpectedly, the Iα (001) and Iβ (100) surfaces are less hydrophilic with contact angles of 48 and 34°, respectively. However, the Iβ (11̅0) plane, often referred to as a hydrophilic surface, forms a contact angle of about 32°. The results are rationalized in terms of structure, exposure of hydroxyl groups to the solvent, and degree of cellulose–cellulose versus cellulose–water hydrogen bonds on each face. The simulations also show that the surface oxidation degree tunes the surface hydrophilicity in a nonlinear manner due to cooperative effects involving water–cellulose interactions. Our study helps us to understand how the degree of hydrophilicity of cellulose emerges from specific structural features of each crystalline surface.
中文翻译:
结晶纤维素的纳米级润湿
纤维素具有广泛的可持续应用的巨大潜力。基于纳米纤维素的材料特性主要取决于其晶面的结构表面特征。结晶纳米纤维素表面与水的亲和力的实验测量很少且难以获得。因此,不同纤维素同质异形体晶面的相对亲水性通常是从其表面的定性评估和极性基团暴露于溶剂中推断出来的。这项工作使用分子动力学模拟研究了纤维素表面的相对亲水性。放置在不同晶面上的水滴的行为用于确定它们的相对亲水性。水分子完全扩散到高度亲水的表面上。然而,放置在亲水性较低的表面上的水滴平衡为扁球形帽,从而可以测量接触角。结果表明,Iα (010)、Iα (11̅0)、Iβ (010) 和 Iβ (110) 面,以及人造纤维素 II 和 III_I (100)、(11̅0)、(010) 的面), 和 (110) 都是高度亲水的。它们都具有低于 11° 的接触角值。不出所料,Iα (001) 和 Iβ (100) 表面的亲水性较低,接触角分别为 48° 和 34°。然而,通常称为亲水表面的 Iβ (11̅0) 平面形成约 32° 的接触角。结果在结构、羟基对溶剂的暴露以及每个面上纤维素-纤维素与纤维素-水氢键的程度方面进行了合理化。模拟还表明,由于涉及水-纤维素相互作用的协同效应,表面氧化度以非线性方式调节表面亲水性。我们的研究帮助我们了解纤维素的亲水性程度如何从每个结晶表面的特定结构特征中显现出来。
更新日期:2021-10-12
中文翻译:
结晶纤维素的纳米级润湿
纤维素具有广泛的可持续应用的巨大潜力。基于纳米纤维素的材料特性主要取决于其晶面的结构表面特征。结晶纳米纤维素表面与水的亲和力的实验测量很少且难以获得。因此,不同纤维素同质异形体晶面的相对亲水性通常是从其表面的定性评估和极性基团暴露于溶剂中推断出来的。这项工作使用分子动力学模拟研究了纤维素表面的相对亲水性。放置在不同晶面上的水滴的行为用于确定它们的相对亲水性。水分子完全扩散到高度亲水的表面上。然而,放置在亲水性较低的表面上的水滴平衡为扁球形帽,从而可以测量接触角。结果表明,Iα (010)、Iα (11̅0)、Iβ (010) 和 Iβ (110) 面,以及人造纤维素 II 和 III_I (100)、(11̅0)、(010) 的面), 和 (110) 都是高度亲水的。它们都具有低于 11° 的接触角值。不出所料,Iα (001) 和 Iβ (100) 表面的亲水性较低,接触角分别为 48° 和 34°。然而,通常称为亲水表面的 Iβ (11̅0) 平面形成约 32° 的接触角。结果在结构、羟基对溶剂的暴露以及每个面上纤维素-纤维素与纤维素-水氢键的程度方面进行了合理化。模拟还表明,由于涉及水-纤维素相互作用的协同效应,表面氧化度以非线性方式调节表面亲水性。我们的研究帮助我们了解纤维素的亲水性程度如何从每个结晶表面的特定结构特征中显现出来。