Characterization of Ultrathin Films of Cellulose Esters

The adsorption of cellulose acetate (CA), cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) from solutions prepared in acetone onto silicon wafers led to ultrathin films, which were characterized by ellipsometry, atomic force microscopy (AFM) and contact angle measurements. The polysaccharides films were characterized in the air just after their formation and after annealing at temperatures higher than their glass transition temperature or melt temperature. The films thickness close to 2 nm and surface roughness did not vary significantly upon annealing. AFM images revealed the presence of small clumps dispersed on a homogeneous layer, which covered completely the Si wafers. Such topographic details were also observed after annealing. However, upon annealing the films surfaces changed from hydrophilic to hydrophobic, evidencing molecular re-orientation at the solid–air interface. The adhesion of bovine serum albumin (BSA) and lipase onto the cellulose esters films was quantified in order to evaluate the possibility of applying such films as selective support for biomolecules.     

Responsive Mesoporous Photonic Cellulose Films by Supramolecular Cotemplating

Cellulose‐based materials have been and continue to be exceptionally important for humankind. Considering the bioavailability and societal relevance of cellulose, turning this renewable resource into an active material is a vital step towards sustainability. Herein we report a new form of cellulose‐derived material that combines tunable photonic properties with a unique mesoporous structure resulting from a new supramolecular cotemplating method. A composite of cellulose nanocrystals and a urea–formaldehyde resin organizes into a chiral nematic assembly, which yields a chiral nematic mesoporous continuum of desulfated cellulose nanocrystals after alkaline treatment. The mesoporous photonic cellulose (MPC) films undergo rapid and reversible changes in color upon swelling, and can be used for pressure sensing. These new active mesoporous cellulosic materials have potential applications in biosensing, optics, functional membranes, chiral separation, and tissue engineering.     

Utilizing Polymer Blends to Prepare Ultrathin Films with Diverse Cellulose Textures

This paper presents an overview of the recent work on ultrathin polymer blend films containing cellulose. Three systems prepared via trimethylsilyl cellulose derivative, which is subsequently hydrolyzed to cellulose, are presented: polystyrene/cellulose, poly(methyl methacrylate)/cellulose and polystyrene-block-polyethyleneoxide/cellulose. Diverse textures emerge within the films depending on the interactions between the polymers and their interactions with the substrate as well as on different solubilities of the polymers. Furthermore, an ultrathin film containing a cellulose/xylan blend is presented. This film was deposited directly from a common solvent (dimethylacetamide/lithium chloride) and it did not exhibit distinct morphological patterns comparable to the blends with synthetic polymers.     

由有机LB膜制备无机超薄膜

无机超薄膜的优异性能引起人们的广泛兴趣，本文介绍几种由有机ＬＢ膜制备无机超薄膜的方法。     

Plasticization Kinetics and Supramolecular Structure of the Cellulose Nitrates Obtained from Different Cellulose-Containing Raw Materials

Russian Journal of General Chemistry - The kinetics of plasticization and the supramolecular structure of the cellulose nitrates obtained from wood, flax, and cotton celluloses were studied. These...     

二氧化钛超薄膜的组装

近年来LB膜技术和超微粒子研究的发展，将两者有效地结合起来组装了与量子电子学、非线性光学、光电化学、化学生物传感器有关的纳米量级无机半导体材料［‘－‘j．其中TIO。纳米薄膜材料已在太阳能电池反射膜、压电铁电薄膜、电致显示器件［‘j、可逆光电池和超导薄膜［’］研究中都显示了广阔的应用前景．这类薄膜制备多采用化学气相沉积（CVD）技术和原子层外延．也有人把LB技术应用于纳米粒子的组装来制备TIO。超薄膜［”’j二本文利用烷氧基钛在水／空气界面上发生的溶胶一凝胶化反应制备TIO。基胶态粒子及其固态凝聚膜，将其与…     

有序分子膜技术在无机超薄膜制备中的应用

本文以LB技术、自组装技术、SILAR方法为例简要介绍了近年来有序分子膜技术在无机超薄膜构筑方面的应用。并对其今后的发展进行了展望。     

再生纤维素荧光膜

由纤维素铜氨溶液与钒磷酸钇：铕，铝酸钡镁；铕，硫化锌镉：铜和硅酸锌：锰荧光粉混合分别制备了４种再生纤维素荧光膜，研究了这些膜的荧光光谱，相对荧光强度，结晶度及力学性能变化。实验结果表明当添加５％荧光粉时，含钒磷酸钇：铕，铝酸钡镁：铕和硫化锌镉：铜的膜仍保持光粉的结晶峰，在紫外光照射下分别发出红，蓝，黄荧光，其相对荧光强度依次为８１％，７９％及７４％。当膜含５％硅酸锌：锰时，在紫外光照射下发射微弱的     

Electrochemical Production of Ultrathin Silicon Dioxide Films

Low-temperature synthesis of ultrathin (20 nm) SiO₂ films, by anodizing semiconductor single-crystal silicon wafers, is studied. Effects of physicochemical properties of electrolyte and single-crystal silicon on the films' dielectric characteristics are considered.     

Fabrication of Hollow Materials by Fast Pyrolysis of Cellulose Composite Fibers with Heterogeneous Structures

A facile method for the fabrication of inorganic hollow materials from cuprammonium cellulose composite filaments based on fast pyrolysis has been developed. Unlike Ostwald ripening, approaches based on the Kirkendall effect, and other template methods, this process yielded hollow materials within 100 s. The heterogeneous structure of the cellulose composite fibers and the gradient distribution of the metal oxides are the main reasons for the formation of the hollow structure. The diameter, wall thickness, and length of the hollow microfibers could be conveniently controlled. With their perfect morphology, these hollow structural materials have great potential for use in various fields.     

导电聚合物超薄膜的制备及性能表征

采用修饰LB膜法制备了导电聚合物聚-3,4-乙烯二氧噻吩/硬脂酸(PEDOT/SA)复合超薄膜. 将硬脂酸(SA)/FeCl3 LB膜暴露于EDOT单体气氛中, EDOT 单体在多层膜中聚合, 制备了PEDOT/SA多层复合LB膜. 紫外-可见光-近红外(UV-Vis-NIR)吸收光谱和X射线光电子能谱(XPS)分析表明EDOT单体在多层膜中发生聚合并生成PEDOT导电聚合物. 扫描电子显微镜(SEM)分析显示生成的PEDOT导电聚合物颗粒分散于硬脂酸LB膜中, 被LB 膜所包裹. 二次离子质谱(SIMS)及XPS分析还发现S元素含量随LB 膜的深度变化而变化, 表明PEDOT 较好地分散于多层膜中. 采用四探针电导率仪对复合多层膜的电导率进行了测试, 结果显示60 层复合LB 膜的电导率为2.6 S·cm-1, 比普通PEDOT薄膜的电导率高一个数量级, 且表现出较好的掺杂/脱掺杂能力. 研究还发现复合膜电导率与薄膜在EDOT 单体中处理时间有关, 处理时间至120 min 后电导率达到最大值并趋于稳定, 氧化剂浓度较低可能影响EDOT在LB膜中的聚合反应速率. 对复合LB 膜的气敏特性进行了分析, 发现在较低气体浓度范围(φ<30×10^-6), PEDOT 复合LB 膜有较快的反应速率, 气敏性与气体浓度呈非线性. 在较高浓度范围(φ=(30-120)×10^-6), 气敏性与浓度呈较好的线性关系. PEDOT复合LB膜对HCl气体表现出较好的响应恢复特性. 同时对PEDOT 复合膜相关的导电机理及气体敏感机理进行了分析.     

Modulation of Supramolecular Interactions of Urea-based Supramolecular Polymers via Molecular Structures

Linear bis-urea D230 series and branched tris-urea T403 series of supramolecular monomers were synthesized using low molecular weight polyetheramine D230, T403 and isocyanates with diverse functional groups. Rheological tests reveal that the materials possess special thermal and mechanical properties due to the strong hydrogen bonding interactions between terminal urea groups and the high flexibility of the polyetheramine middle segments. By enhancing the hydrogen bonding interactions through electronic effects of the substituted urea groups, the mechanical properties of the bulk material can be increased. Moreover, the branched T403 series with higher hydrogen bonding density also shows better performance against D230 series with the same substituted urea groups. The presence of π-π stacking between the phenyl groups in samples with phenylurea residues, which complements the hydrogen bonding, was also confirmed by fluorescence spectroscopy, therefore resulting in a stronger supramolecular polymer network.     

Optical Properties of Noble Metal Clusters in Ultrathin Solid Films

We report on the optical properties (absorption, Raman response) of thin and ultrathin phthalocyanine and amorphous silicon films with incorporated noble metal clusters. The metal clusters cause the typical absorption features originating from their surface plasmon resonance. In ultrathin films, due to the spatially close interface, the plasmon absorption may be displaced from its resonance frequency in the bulk, and its average position may be controlled by the average thickness of the ultrathin optical film. For example, we observe a shift of the plasmon resonance of silver clusters in amorphous silicon films (on fused silica) from 440 nm to 740 nm, when the silicon thickness increases from zero up to 9 nm. The deposition experiments are accompanied by investigations of the film structure, particularly in order to estimate the silver cluster diameter, which is around 3 nm or less.     

Effect of Supramolecular and Morphological Structure on Cellulose Characteristics

The dependence of quality indicators of cotton cellulose obtained by an oxygen-alkaline digestion method, cellulose from the Bakai company, and wood cellulose on their supramolecular and morphological structure was studied by various physicochemical methods. The number of gel particles in cellulose solutions depends on their degree of polymerization; in solutions of their Na-CMC esters, on the content of the primary fiber wall of the starting cellulose     

有机硅超分子材料研究进展

有机硅材料具有优异的热稳定性、生物相容性、电绝缘性能和透气性等,在国民经济各个领域已得到广泛应用.近年来,具有自修复和可塑性的有机硅超分子材料引起了人们的广泛关注,各种各样的功能材料不断被开发出来.本文综合评述了有机硅超分子材料的合成、性能和应用等方面的近期研究进展,重点阐述了氢键型、金属配位键型、Lewis酸碱对型、离子键型及π-π堆积型有机硅超分子材料,并对其发展前景进行了展望.     

Supramolecular Materials Chemistry in the MacLachlan Group

This invited Team Profile was created by the MacLachlan group at the University of British Columbia . They recently published an article on the uniform growth of a metal–organic framework, ZIF-8, on the surface of individual cellulose nanocrystals (CNCs). After the ZIF-8/CNC fibers had been coated with a microporous organic polymer, the ZIF-8 was removed to leave a microporous polymer with CNCs encapsulated in a ship-in-a-bottle architecture. This material proved to be effective for CO₂ fixation. “Uniform Growth of Nanocrystalline ZIF-8 on Cellulose Nanocrystals: Useful Template for Microporous Organic Polymers”, K. Cho, L. J. Andrew, M. J. MacLachlan, Angew. Chem. Int. Ed. 2023 , e202300960 .