From Chitin Nanowhisker Colloidal Dispersions to Anisotropic Microfibers: Structural Evolution in Its Transformation Process as Revealed by Synchrotron Wide-Angle X-ray Diffraction Measurements,ACS Macro Letters

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From Chitin Nanowhisker Colloidal Dispersions to Anisotropic Microfibers: Structural Evolution in Its Transformation Process as Revealed by Synchrotron Wide-Angle X-ray Diffraction Measurements
ACS Macro Letters ( IF 5.1 ) Pub Date : 2024-08-22 , DOI: 10.1021/acsmacrolett.4c00335
Phanicha Wiwatsamphan ₁ , Kohji Tashiro ₂ , Hiroyasu Masunaga ₃ , Sono Sasaki _{4,

5} , Suwabun Chirachanchai ₁

Affiliation

Nanowhiskers in a colloidal dispersion are known to form chiral nematic liquid crystals (CNLC), as seen in a cellulose nanowhisker or so-called cellulose nanocrystal and chitin nanowhisker. In our related work, we clarified that once the thus-created chitin nanowhiskers with surface modified by chitosan (CTWK-CS) in CNLC phase were wet-spun, we could directly obtain anisotropic microfibers containing the highly ordered CTWK-CS. This drastic structural transformation from CNLC to anisotropic microfibers might relate to several important stages, i.e., stage (i) is the alignment of CTWK-CS initiated by a specific concentration and flow to create aggregation in the CNLC state, stage (ii) is the coagulation of CTWK-CS in CNLC to transform to microfibers, and stage (iii) is the drying of the thus-extruded microfibers to allow CTWK-CS alignment. The present work sets up the experimental systems simulating stages (i) and (iii) to reveal the orientational behavior of CTWK-CS and the structural evolution, respectively, by synchrotron 2D WAXD measurement. In stage (i), the high degree of the parallel alignments of CTWK-CS with the chain axis oriented along the flow direction of the colloidal dispersions confirms that the flow and concentration synergistically controlled CTWK-CS alignment. In contrast, for stage (iii), the poor c-axial orientation of CTWK-CS in as-spun wet microfibers gradually changed to the high degree of c-axial orientation along the fiber direction during drying process, indicating a reorientation of CTWK-CS along with dehydration. The present study declares an in situ observation of the direct wet spinning of nanowhiskers about their remarkable alignments in the sheared colloidal dispersions (stage (i)) and their random-to-high reorientation during the drying process of the as-spun wet microfiber (stage (iii)).

中文翻译：

从甲壳素纳米晶须胶体分散体到各向异性微纤维：同步加速器广角 X 射线衍射测量揭示其转变过程中的结构演化

已知胶体分散体中的纳米晶须形成手性向列液晶（CNLC），如纤维素纳米晶须或所谓的纤维素纳米晶体和甲壳质纳米晶须中所见。在我们的相关工作中，我们阐明，一旦将CNLC相中壳聚糖表面改性的甲壳素纳米晶须（CTWK-CS）进行湿纺，我们就可以直接获得含有高度有序的CTWK-CS的各向异性微纤维。这种从 CNLC 到各向异性微纤维的剧烈结构转变可能与几个重要阶段有关，即阶段 (i) 是由特定浓度和流量引发的 CTWK-CS 排列，以在 CNLC 状态下产生聚集，阶段 (ii) 是CTWK-CS在CNLC中凝固转变为微纤维，并且阶段(iii)是干燥由此挤出的微纤维以允许CTWK-CS排列。目前的工作建立了模拟阶段 (i) 和 (iii) 的实验系统，通过同步加速器 2D WAXD 测量分别揭示 CTWK-CS 的取向行为和结构演化。在阶段(i)中，CTWK-CS与沿着胶体分散体的流动方向定向的链轴的高度平行排列证实了流动和浓度协同控制CTWK-CS排列。相反，对于阶段(iii)，在干燥过程中，初纺湿微纤维中CTWK-CS的较差c轴取向逐渐转变为沿纤维方向的高度c轴取向，这表明CTWK-CS重新取向。 CS伴随脱水。本研究宣称对纳米晶须的直接湿法纺丝进行了原位观察，观察它们在剪切胶体分散体中的显着排列（阶段（i））以及在初纺湿微纤维的干燥过程中它们的随机至高度重新取向（阶段(iii))。

更新日期：2024-08-22

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