Yi Kong,Xingyu Lan,Weixiong Zhang,Shao-Yuan Leu,Chuanshuang Hu,Ying Wang,Shiyu Fu
It is an interesting research topic to study the interfacial interactions between hemicellulose and cellulose, specifically how hemicellulose's structure affects its binding to cellulose nanofibers. Our research proposes that dispersion interaction play an important role in this interfacial interaction, more so than electrostatic forces when considering the adherence of cellulose to xylan. To quantify these interactions, the Atomic Force Microscope (AFM) colloidal probe technique is applied to measure the intermolecular forces between cellulose nanofibers, which are attached to the probe and xylan. These measured forces are then analyzed in relation to the length, diameter and functional groups of the nanocellulose, as well as the molecular weight and side chains of the xylan. Moreover, the predominance of dispersion forces by contrasting the adhesive forces before and after the grafting of a large nonpolar group onto xylan. This modification significantly reduces contact between the cellulose and xylan backbone, thereby markedly diminishing the dispersion interactions. Parallel to the AFM experiments, molecular dynamics (MD) simulations corroborate the experimental results and support our hypotheses. Collectively, these findings contribute to a deeper understanding of polysaccharide interactions within lignocellulose.
Obtaining the interaction between two substances in liquid through their molecular structures can promote the design and preparation of new functional materials. When multiple types of intermolecular forces coexist, whether the contribution terms generated by each type of intermolecular force have the same scaling factor is a key consideration. In this paper, an empirical equation for calculating the total intermolecular interaction is proposed. The required molecular property parameters for calculation can be obtained through quantum–chemical calculation. For the experiments of removing eight ionic dyes in water by using corn cobs as adsorbents, linear correlation was found between the removal percentage and the total interaction calculated from the proposed equation. When the scaling factors of polar and hydrogen bond interaction terms are 1, the scaling factor of dispersion force interaction term in the equation is greater than 2.5.
Development of facile and effective methods for fabrication of high-performance solid phase microextraction (SPME) fibres remains a great challenge. Herein, a new class of ordered mesoporous polymers (OMPs) in situ coated on a stainless steel wire were successfully developed and utilized as a highly sensitive and stable SPME fibre for the first time. Because of the highly ordered mesoporous structure of its OMP coating, the π–π interactions and the dispersion forces, the OMP-coated SPME fibre exhibited much better extraction properties as compared to the commercial PDMS fibre. The findings could provide a new benchmark for preparing well-defined porous materials for the SPME application.
Caiyun Liu,Lulu Wu,Zengshuai Zhang,Ziying Li,Mario Prejanò,Tiziana Marino,Yongsheng Tao,Yunkui Li
This study was aimed to explore the effect of α-cyclodextrin (α-CD) on color quality and stability of red wines, and to dissect the mechanism of copigmentation at molecular level. Firstly, α-CD was added to real wine before fermentation and aging dynamics were monitored. This study found that α-CD enhanced visual quality by strengthening anthocyanins maceration during fermentation, yet α-CD improved color stability by promoting formation of color-stable polymeric anthocyanins during aging. Secondly, the thermodynamics and dose-effect relationships in model wines revealed that binding between α-CD and malvidin-3- O -glucoside (Mvd-G) was a spontaneous exothermic reaction driven by enthalpy, with an optimal molar ratio of 1:5. Finally, structural characterization of host-guest complex and electronic effects of intermolecular interactions revealed that Mvd-G successfully formed host-guest complex with α-CD through hydrogen bonding and dispersion. The hydroxyl group and glucoside in the anthocyanin C ring, as well as the primary hydroxyl group of the α-CD were the key structures for forming hydrogen bonds. The results of this study provided an experimental and theoretical basis for the applications of α-CD as copigment to enhance the color quality and stability.
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