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Cellulose nanocrystals (CNCs) self-assemble and can be flow-assembled to liquid crystalline orders in a water suspension. The orders range from nano- to macroscale with the contributions of individual crystals, their micron clusters, and macroscopic assemblies. The resulting hierarchies are optically active materials that exhibit iridescence, reflectance, and light transmission. Although these assemblies have the potential for future renewable materials, details about structures on different hierarchical levels that span from the nano- to the macroscale are still not unraveled. Rheological characterization is essential for investigating flow properties; however, bulk material properties make it difficult to capture the various length-scales during assembly of the suspensions, for example, in simple shear flow. Rheometry is combined with other characterization methods to allow direct analysis of the structure development in the individual hierarchical levels. While optical techniques, scattering, and spectroscopy are often used to complement rheological observations, coupling them in situ to allow simultaneous observation is paramount to fully understand the details of CNC assembly from liquid to solid. This Review provides an overview of achievements in the coupled analytics, as well as our current opinion about opportunities to unravel the structural distinctiveness of cellulose nanomaterials.

We present a rapid method based on 2D thin layer chromatography (TLC) for the simultaneous separation and quantification of organic, lipophilic extractives occurring in lignocellulosic biorefinerie...

Abstract The arrangement of cellulose molecules in natural environment on the nanoscale is still not fully resolved, with longitudinal disorder in cellulose microfibrils (CMF) being one relevant question. Particularly the length of the dislocated cellulose segments in CMFs is still under debate. Using molecular dynamics simulations, we are first investigating the phenomenon of pseudo-recrystallization of dislocated cellulose regions after cleavage of CMFs. Based on our simulations we propose that 3–4 glucose residues bordering to each side of a cellulose nanocrystal are actually reorganizing to a quasi-crystalline state, which are corroborating recent analytical investigations reporting an increase in crystallinity after acid vapor hydrolysis of CMFs. Combining our molecular dynamics simulation results with these analytical data we can estimate the length of the dislocated cellulose segments in CMFs. We propose that, for the investigated sources of biomass (cotton and ramie), the dislocation lengths are between 3.1–5.8 nm equaling to 6–11 glucose residues in the cellulose crystallites. Graphic abstract

Cellulose carbamate (CC) was employed as a water-soluble precursor in the manufacturing of cellulose based thin films using the spin coating technique. An intriguing observation was that during spin coating of CC from alkaline aqueous solutions, regeneration to cellulose was accomplished without the addition of any further chemicals. After rinsing, homogeneous thin films with tunable layer thickness in a range between 20 and 80 nm were obtained. Further, CC was blended with cellulose xanthate in different ratios (3:1, 1:1, 1:3) and after regeneration the properties of the resulting all-cellulose blend thin films were investigated. We could observe some slight indications of phase separation by means of atomic force microscopy. The layer thickness of the blend thin films was nearly independent of the ratio of the components, with values between 50 and 60 nm for the chosen conditions. The water uptake capability (80-90% relative to the film mass) determined by H2O/D2O exchange in a quartz crystal microbalance was independent of the blend ratio.

A generic procedure for the manufacturing of cellulose-metal sulfide multilayered sandwich type thin films is demonstrated at the example of copper indium sulfide. These multilayers were created by alternate spin coating steps of precursors, followed by their conversion using either acidic vapors, or heat treatment. As precursors, cellulose xanthate, a widely available cellulose derivative employed in viscose fiber manufacturing and commercial copper and indium xanthates were used. After conversion of the single layers into cellulose and copper indium sulfide, the film properties (structure, thickness, photoelectric activity) of the single and multilayer systems consisting of alternate layers of cellulose and copper indium sulfide were studied. For the proof of concept, up to five layers were built up, showing a clear separation of the cellulose and the metal sulfide layers as demonstrated using cross sectional analysis using ion slope beam cutting and SEM imaging. Finally, the conversion of xanthates was performed using UV light and a mask, allowing for the creation of 2D patterns. ispartof: CARBOHYDRATE POLYMERS vol:203 pages:219-227 ispartof: location:England status: published

Funding Information: This work was partially funded by the Academy of Finland's Flagship Programme under Projects No. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES). Publisher Copyright: © 2021 The Author(s) Copyright: Copyright 2021 Elsevier B.V., All rights reserved. The increasing amount of electric vehicles on our streets as well as the need to store surplus energy from renewable sources such as wind, solar and tidal parks, has brought small and large scale batteries into the focus of academic and industrial research. While there has been huge progress in performance and cost reduction in the past years, batteries and their components still face several environmental issues including safety, toxicity, recycling and sustainability. In this review, we address these challenges by showcasing the potential of polysaccharide-based compounds and materials used in batteries. This particularly involves their use as electrode binders, separators and gel/solid polymer electrolytes. The review contains a historical section on the different battery technologies, considerations about safety on batteries and requirements of polysaccharide components to be used in different types of battery technologies. The last sections cover opportunities for polysaccharides as well as obstacles that prevent their wider use in battery industry.

Cellulose hydrolysis is an extensively studied process due to its relevance in the fields of biofuels, chemicals production, and renewable nanomaterials. However, the direct visualization of the process accompanied with detailed scaling has not been reported because of the vast morphological alterations occurring in cellulosic fibers in typical heterogeneous (solid/liquid) hydrolytic systems. Here, we overcome this distraction by exposing hardwood cellulose nanofibers (CNFs) deposited on silica substrates to pressurized HCl gas in a solid/gas system and examine the changes in individual CNFs by atomic force microscopy (AFM). The results revealed that hydrolysis proceeds via an intermediate semi-fibrous stage before objects reminiscent of cellulose nanocrystals were formed. The length of the nanocrystal-like objects correlated well with molar mass, as analyzed by gel permeation chromatography, performed on CNF aerogels hydrolyzed under identical conditions. Meanwhile, X-ray diffraction showed a slight increasein crystallinity index as the hydrolysis proceeded. The results provide a modern visual complement to >100 years of research in cellulose degradation.

Cellulosic nanomaterials are in the focus of academia and industry to realize light-weight biobased materials with remarkable strength. While the effect is well known, the distribution of these nanomaterials are less explored, particularly for paper sheets. Here, we explore the 3D distribution of micro and nanosized cellulosic particles in paper sheets and correlate their extent of fibrillation to the distribution inside the sheets and subsequently to paper properties. To overcome challenges with contrast between the particles and the matrix, we attached probes on the cellulose nano/microparticles, either by covalent attachment of fluorescent dyes or by physical deposition of cobalt ferrite nanoparticles. The increased contrast enabled visualization of the micro and nanosized particles inside the paper matrix using multiphoton microscopy, X-ray microtomography and SEM-EDX. The results indicate that fibrillary fines enrich at pores and fiber-fiber junctions, thereby increasing the relative bonded area between fibers to enhance paper strength while CNF seems to additionally form an inner 3D network.

Optical brightening agents (OBAs) are commonly used in textile and paper industry to adjust product brightness and color appearence. Continuous production processes lead to short residence time of the dyes in the fiber suspension, making it necessary to understand the kinetics of adsorption. The interaction mechanisms of OBAs with cellulose are challenging to establish as the fibrous nature of cellulosic substrates complicates acquisition of real-time data. Here, we explore the real-time adsorption of different OBAs (di, tetra- and hexasulfonated compounds) onto different cellulose surfaces using surface plasmon resonance spectroscopy. Ionic strength, surface topography and polarity were varied and yielded 0.76-11.35 mg m-2 OBA on cellulose. We identified four independent mechanisms governing OBA-cellulose interactions. These involve the polarity of the cellulose surface, the solubility of the OBA, the ionic strength during adsorption and presence of bivalent cations such as Ca2+. These results can be exploited for process optimization in related industries as they allow for a simple adjustment and experimental testing procedures including performance assessment of novel OBAs. ispartof: CARBOHYDRATE POLYMERS vol:261 ispartof: location:England status: published

Periodate oxidation of polysaccharides has transitioned from structural analysis into a modification method for engineered materials. This review summarizes the research on this topic. Fibers, fibrils, crystals, and molecules originating from forests that have been subjected to periodate oxidation can be crosslinked with other entities via the generated aldehyde functionality, that can also be oxidized or reduced to carboxyl or alcohol functionality or used as a starting point for further modification. Periodate-oxidized materials can be subjected to thermal transitions that differ from the native cellulose. Oxidation of polysaccharides originating from forests often features oxidation of structures rather than liberated molecules. This leads to changes in macro, micro, and supramolecular assemblies and consequently to alterations in physical properties. This review focuses on these aspects of the modulation of structural hierarchies due to periodate oxidation.

Biopolymer cellulose is investigated in terms of the crystallographic order within thin films. The films were prepared by spin-coating of a trimethylsilyl cellulose precursor followed by an exposure to HCl vapors; two different source materials were used. Careful precharacterization of the films was performed by infrared spectroscopy and atomic force microscopy. Subsequently, the films were investigated by grazing incidence X-ray diffraction using synchrotron radiation. The results showed broad diffraction peaks, indicating a rather short correlation length of the molecular packing in the range of a few nanometers. The analysis of the diffraction patterns was based on the known structures of crystalline cellulose, as the observed peak pattern was comparable to cellulose phase II and phase III. The dominant fraction of the film is formed by two different types of layers, which are oriented parallel to the substrate surface. The stacking of the layers results in a one-dimensional crystallographic order with a defined interlayer distance of either 7.3 or 4.2 A. As a consequence, two different preferred orientations of the polymer chains are observed. In both cases, polymer chain axes are aligned parallel to the substrate surface, and the orientation of the cellulose molecules are concluded to be either edge-on or flat-on. A minor fraction of the cellulose molecules form nanocrystals that are randomly distributed within the films. In this case, the molecular packing density was found to be smaller in comparison to the known crystalline phases of cellulose.

Industrially relevant, commercially available cationic starches have been investigated towards their interaction capacity with cellulose thin films derived from trimethylsilyl cellulose (TMSC). The starches used in this study stem from different sources (potato, pea, corn) and featured rather low degrees of substitution ranging from 0.030 to 0.062. The interaction of those starches with cellulose thin films was studied by surface plasmon resonance spectroscopy under flow conditions using concentrations of 1.0mgml-1 and a flow rate of 25μlmin-1. All the investigated starches employed in this study were capable to efficiently interact with the slightly negatively charged cellulose surface leading to irreversible deposition on the surface. As complementary techniques atomic force microscopy and x-ray photoelectron spectroscopy were used to confirm the presence of the starches on the cellulose film surface. Further, dynamic light scattering and size exclusion chromatography measurements were performed to correlate adsorbed amount, particle size and molecular weight of the starches to their interaction behavior.

The preparation and characterization of cellulose thin films derived from cellulose xanthate is reported. The films are prepared by depositing alkaline aqueous solutions of cellulose xanthate onto silicon wafers, followed by a spin coating step. Depending on the xanthate concentration used for spin coating, films with 50 and 700 nm thickness are obtained. The cellulose xanthate is converted to cellulose by exposing the films to HCl vapors over a period of 20 min. The conversion is monitored by ATR-IR spectroscopy, which allows for tracking the rupture of C–S and C=S bonds during the regeneration process. The conversion is accompanied by a reduction of the film thickness of ca 40% due to the removal of the bulky xanthate group. The films feature a homogenous, but porous morphology as shown by atomic force microscopy. Further, the films were investigated towards their interaction with Bovine Serum Albumin (BSA) and fibrinogen by means of multi-parameter surface plasmon resonance spectroscopy. Similar as other cellulose thin films BSA adsorption is low while fibrinogen adsorbs to some extent at physiological pH (7.4).

The effect of fatty acids and fatty acid esters to impair nonspecific protein adsorption on cellulose thin films is investigated. Thin films are prepared by blending trimethylsilyl cellulose solutions with either cellulose stearoyl ester or stearic acid at various ratios. After film formation by spin coating, the trimethylsilyl cellulose fraction of the films is converted to cellulose by exposure to HCl vapors. The morphologies and surface roughness of the blends were examined by atomic force microscopy revealing different feature shapes and sizes depending on the blend ratios. Nonspecific protein adsorption at the example of bovine serum albumin toward the blend thin films was tested by means of surface plasmon resonance spectroscopy in real-time. Incorporation of stearic acid into the cellulose leads to highly protein repellent surfaces regardless of the amount added. The stearic acid acts as a sacrificial compound that builds a complex with bovine serum albumin thereby inhibiting protein adsorption. For the blends where stearoyl ester is added to the cellulose films, the cellulose:cellulose stearoyl ester ratios of 3:1 and 1:1 lead to much lower nonspecific protein adsorption compared to pure cellulose, whereas for the other ratios, adsorption increases. Supplementary results were obtained from atomic force microscopy experiments performed in liquid during exposure to protein solution and surface free energy determinations.

The synthesis and characterization of bismuth sulfide-cellulose nanocomposite thin films was explored. The films were prepared using organosoluble precursors, namely bismuth xanthates for Bi2S3 and trimethylsilyl cellulose (TMSC) for cellulose. Solutions of these precursors were spin coated onto solid substrates yielding homogeneous precursor films. Afterwards, a heating step under inert atmosphere led to the formation of thin nanocomposite films of bismuth sulfide nanoparticles within the TMSC matrix. In a second step, the silyl groups were cleaved off by vapors of HCl yielding bismuth sulfide/cellulose nanocomposite films. The thin films were characterized by a wide range of surface sensitive techniques such as atomic force microscopy, attenuated total reflection infrared spectroscopy, transmission electron microscopy and wettability investigations. In addition, the formation of the nanoparticle directly in the TMSC matrix was investigated in situ by GI-SWAXS using a temperature controlled sample stage.

Nonspecific protein deposition on Lyocell fibers via a cationization step was explored by adsorption of two different N,N,N -trimethyl chitosan chlorides (TMCs). Both, the cationization and the subsequent protein deposition steps were performed and monitored in situ by evaluating the zeta potential using the streaming potential method. Both employed TMCs (degree of substitution with N + Me 3 Cl groups: 0.27 and 0.64) irreversibly adsorb on the fibers as proven by charge reversal (−12 to +7 mV for both derivatives) after the final rinsing step. Onto these cationized fibers, BSA was deposited at different pH values (4, 5, and 7). Charge titrations revealed that close to the isoelectric point of BSA (4.7), BSA deposition was particularly favored, while at lower pH values (pH 4), hardly any adsorption took place due to electrostatic repulsion of the cationic fibers and the positively charged BSA. This work sets the foundation for further investigations to use zeta potential measurements for protein adsorption studies on fibrous materials.

A generic approach to design optoelectronic devices using renewable biopolymers is demonstrated. As a proof of principle, a biopolymer/CuInS2 nanocomponent-based solar cell has been assembled by using a cellulose derivative with a reasonable life cycle performance, namely, trimethylsilyl cellulose (TMSC). The solar cells are manufactured using a mixture of copper and indium xanthates as precursors, which decompose and form CIS nanoparticles within the biopolymer matrix during a thermal treatment, which was investigated by in situ combined grazing incidence small and wide-angle X-ray scattering experiments. The growth of the nanoparticles is thereby controlled by the TMSC matrix. The nanocrystals exhibit an average diameter of approximately 4 nm. Using this composite, it was possible to fabricate solar cells, generating current in a wide range of the solar spectrum and exhibiting power conversion efficiencies of ca. 1%.

The creation of nano- and micropatterned polymer films is a crucial step for innumerous applications in science and technology. However, there are several problems associated with environmental aspects concerning the polymer synthesis itself, cross-linkers to induce the patterns as well as toxic solvents used for the preparation and even more important development of the films (e.g., chlorobenzene). In this paper, we present a facile method to produce micro- and nanopatterned biopolymer thin films using enzymes as so-called biodevelopers. Instead of synthetic polymers, naturally derived ones are employed, namely, poly-3-hydroxybutyrate and a cellulose derivative, which are dissolved in a common solvent in different ratios and subjected to spin coating. Consequently, the two biopolymers undergo microphase separation and different domain sizes are formed depending on the ratio of the biopolymers. The development step proceeds via addition of the appropriate enzyme (either PHB-depolymerase or cellulase), whereas one of the two biopolymers is selectively degraded, while the other one remains on the surface. In order to highlight the enzymatic development of the films, video AFM studies have been performed in real time to image the development process in situ as well as surface plasmon resonance spectroscopy to determine the kinetics. These studies may pave the way for the use of enzymes in patterning processes, particularly for materials intended to be used in a physiological environment.

A literature review on ultrathin films of cellulose is presented. The review focuses on different deposition methods of the films – all the way from simple monocomponent films to more elaborate multicomponent structures – and the use of the film structures in the vast realm of materials science. The common approach of utilizing cellulose thin films as experimental models is therefore omitted. The reader will find that modern usage of cellulose thin films constitutes an exciting emerging area within materials science and it goes far beyond the traditional usage of the films as model systems.

Generated in the pulp and paper production process, cellulosic pulp fines are fibrous cellulosic materials capable of passing a 200 mesh screen. Processed pulp fines remain in the pulp and affect pulp and paper sheet properties. Their specific morphology promotes interactions with fibers and alters sheet properties. Nevertheless, the 3D distribution of fines in paper sheets has not been revealed so far. Localizing fines within a matrix of fibers is challenging since both elements have the same chemical composition and fines have small dimensions. It is required to increase the contrast of pulp fines, while avoiding any alteration of initial fines morphology. In this study, fines were first separated and labeled with Rhodamine B isothiocyanate, a fluorescent dye. Labeled fines were blended with pulp at different concentrations and paper sheets were produced from each mixture. Prior to imaging, pulps and handsheets were characterized by standard pulp and paper tests and compared with references, showing no significant differences between sheets containing labeled and untreated fines. Thus, mechanical and physical tests indicated that no, or only minor alteration of fines properties by the labeling process occurred. We then applied two imaging techniques to detect the labeled pulp fines in the paper network, namely confocal laser scanning microscopy and multiphoton microscopy, visualizing the 3D distribution of fluorescent fines within the fiber network. The results obtained also allowed a differentiation between morphologically different fines showing fiber fragments more attached to single fibers whereas more fibrillar fines concentrate in fiber–fiber joints, thereby strengthening bonding.

Cellulose derivate phase separation in thin films was applied to generate patterned films with distinct surface morphology. Patterned polymer thin films are utilized in electronics, optics, and biotechnology but films based on bio-polymers are scarce. Film formation, roughness, wetting, and patterning are often investigated when it comes to characterization of the films. Frictional properties, on the other hand, have not been studied extensively. We extend the fundamental understanding of spin coated complex cellulose blend films via revealing their surface friction using Friction Force Microscopy (FFM). Two cellulose derivatives were transformed into two-phase blend films with one phase comprising trimethyl silyl cellulose (TMSC) regenerated to cellulose with hydroxyl groups exposed to the film surface. Adjusting the volume fraction of the spin coating solution resulted in variation of the surface fraction with the other, hydroxypropylcellulose stearate (HPCE) phase. The film morphology confirmed lateral and vertical separation and was translated into effective surface fraction. Phase separation as well as regeneration contributed to the surface morphology resulting in roughness variation of the blend films from 1.1 to 19.8 nm depending on the film composition. Friction analysis was successfully established, and then revealed that the friction coefficient of the films could be tuned and the blend films exhibited lowered friction force coefficient compared to the single-component films. Protein affinity of the films was investigated with bovine serum albumin (BSA) and depended mainly on the surface free energy (SFE) while no direct correlation with roughness or friction was found. BSA adsorption on film formed with 1:1 spinning solution volume ratio was an outlier and exhibited unexpected minimum in adsorption.

An approach for the multilayer density analysis of polysaccharide thin films at the example of cellulose is presented. In detail, a model was developed for the evaluation of the density in different layers across the thickness direction of the film. The cellulose thin film was split into a so called "roughness layer" present at the surface and a "bulk layer" attached to the substrate surface. For this approach, a combination of multi-parameter surface plasmon resonance spectroscopy (SPR) and atomic force microscopy (AFM) was employed to detect changes in the properties, such as cellulose content and density, thickness and refractive index, of the surface near layer and the bulk layer. The surface region of the films featured a much lower density than the bulk. Further, these results correlate to X-ray reflectivity studies, indicating a similar layered structure with reduced density at the surface near regions. The proposed method provides an approach to analyse density variations in thin films which can be used to study material properties and swelling behavior in different layers of the films. Limitations and challenges of the multilayer model evaluation method of cellulose thin films were discussed. This particularly involves the selection of the starting values for iteration of the layer thickness of the top layer, which was overcome by incorporation of AFM data in this study.

This study investigates flexible (polyamide 6.6 PA-6.6, polyethylene terephthalate PET, Cu, Al, and Ni foils) and, for comparison, stiff substrates (silicon wafers and glass) differing in, for example, in surface free energy and surface roughness and their ability to host cellulose-based thin films. Trimethylsilyl cellulose (TMSC), a hydrophobic acid-labile cellulose derivative, was deposited on these substrates and subjected to spin coating. For all the synthetic polymer and metal substrates, rather homogenous films were obtained, where the thickness and the roughness of the films correlated with the substrate roughness and its surface free energy. A particular case was the TMSC layer on the copper foil, which exhibited superhydrophobicity caused by the microstructuring of the copper substrate. After the investigation of TMSC film formation, the conversion to cellulose using acidic vapors of HCl was attempted. While for the polymer foils, as well as for glass and silicon, rather homogenous and smooth cellulose films were obtained, for the metal foils, there is a competing reaction between the formation of metal chlorides and the generation of cellulose. We observed particles corresponding to the metal chlorides, while we could not detect any cellulose thin films after HCl treatment of the metal foils as proven by cross-section imaging using scanning electron microscopy (SEM).

Lectins are a diverse class of carbohydrate binding proteins with pivotal roles in cell communication and signaling in many (patho)physiologic processes in the human body, making them promising targets in drug development, for instance, in cancer or infectious diseases. Other applications of lectins employ their ability to recognize specific glycan epitopes in biosensors and glycan microarrays. While a lot of research has focused on lectin interaction with specific carbohydrates, the interaction potential of lectins with different types of surfaces has not been addressed extensively. Here, we screen the interaction of two specific plant lectins, Concanavalin A and Ulex Europaeus Agglutinin-I with different nanoscopic thin films. As a control, the same experiments were performed with Bovine Serum Albumin, a widely used marker for non-specific protein adsorption. In order to test the preferred type of interaction during adsorption, hydrophobic, hydrophilic and charged polymer films were explored, such as polystyrene, cellulose, N,-N,-N-trimethylchitosan chloride and gold, and characterized in terms of wettability, surface free energy, zeta potential and morphology. Atomic force microscopy images of surfaces after protein adsorption correlated very well with the observed mass of adsorbed protein. Surface plasmon resonance spectroscopy studies revealed low adsorbed amounts and slow kinetics for all of the investigated proteins for hydrophilic surfaces, making those resistant to non-specific interactions. As a consequence, they may serve as favorable supports for biosensors, since the use of blocking agents is not necessary.

The chemistry of organo silanetriols is reviewed covering the aspects of synthesis, structural chemistry, reactivity, properties and applications over the last 15 years. Besides relevant progress in established fields like supramolecular chemistry, surface modification and metallasiloxane formation, recent advances include structural investigations in liquid and gaseous states and studies concerning the bio-activity of silanetriols. Based on irreversible condensation starting from silanetriols fascinating cage compounds and cerasomes have been reported as well as silanetriol-modified biopolymers and nanopatterning applications.

Xylan-coated cellulose thin films has been investigated by means of atomic force microscopy (AFM) and force mapping experiments. The birch xylan deposition on the film was performed under control by means of a multiple parameter surface plasmon resonance spectroscopy (MP-SPR) under dynamic conditions. The coated films were submitted to AFM in phase imaging mode to force mapping with modified AFM tips (sensitive to hydrophilic OH and hydrophobic CH3 groups) in order to characterize and localize the xylan on the surfaces. At the first glance, a clear difference in the adhesion force between xylan-coated areas and cellulose has been observed. However, these different adhesion forces originate from topography effects, which prevent an unambiguous identification and subsequent localization of the xylan on the cellulosic surfaces.

In this study, the formation of self-assembled monolayers consisting of three organophosphonic acids (vinyl-, octyl-, and tetradecylphosphonic acid) from isopropanol solutions onto differently activated gold surfaces is studied in situ and in real time using multiparameter surface plasmon resonance (MP-SPR). Data retrieved from MP-SPR measurements revealed similar adsorption kinetics for all investigated organophosphonic acids (PA). The layer thickness of the immobilized PA is in the range of 0.6-1.8 nm corresponding to monolayer-like coverage and correlates with the length of the hydrocarbon chain of the PA molecules. After sintering the surfaces, the PA are irreversibly attached onto the surfaces as proven by X-ray photoelectron spectroscopy and attenuated total reflection infrared and grazing incidence infrared spectroscopy. Potential adsorption modes and interaction mechanisms are proposed.

This review focuses on cationic starches with a low degree of substitution (

Viscose fibers were impregnated with different concentrations of diammonium hydrogen phosphate (DAHP), carbonized, activated, and tested as high-performance electrode materials for supercapacitors. The yield of these activated carbon fibers (ACFs) could be increased by a factor of 14 by using DAHP compared to ACF without impregnation. These specific activation procedures yielded a high specific surface area of more than 2700 m2∙g&minus, 1 with a pore size distribution (PSD) suitable for use as a supercapacitor electrode. The electrode materials were implemented in symmetric supercapacitors using TEMA BF4 as electrolyte and cyclic voltammetry measurements showed high specific capacitances of up to 167 F∙g&minus, 1. Furthermore, the devices showed high energy densities of up to 21.4 W∙h∙kg&minus, 1 and high-power densities of up to 8.7 kW∙kg&minus, 1. The supercapacitors featured high capacity retention (96%) after 10,000 cycles. These results show that ACFs made of viscose fibers, previously impregnated with DAHP, can be used as high-performance electrodes in supercapacitors for energy storage applications.

Katja Heise,1,2 Mathias Hobisch,3,4 Liviu Sacarescu,5 Uros Maver,6 Josefine Hobisch,3 Tobias Reichelt,7 Marija Sega,6 Steffen Fischer,1 Stefan Spirk3,4 Members of EPNOE and NAWI Graz 1Institute of Plant and Wood Chemistry, Technische Universität Dresden, Tharandt, Germany; 2Department of Bioproducts and Biosystems, Aalto University, Espoo, Finland; 3Institute for Chemistry and Technology of Materials, Graz University of Technology, Graz, Austria; 4Institute for Paper, Pulp and Fiber Technology, Graz University of Technology, Graz, Austria; 5“Petru Poni” Institute of Macromolecular Chemistry, Romanian Academy, Iasi, Romania; 6Faculty of Medicine, University of Maribor, Maribor, Slovenia; 7Zentrum für Bucherhaltung GmbH, Leipzig, Germany Purpose: In this work, low-molecular-weight sulfoethyl chitosan (SECS) was used as a model template for the generation of silver core-shell nanoparticles with high potential as anticoagulants for medical applications. Materials and methods: SECS were synthesized by two reaction pathways, namely Michael addition and a nucleophilic substitution with sodium vinylsulfonate or sodium 2-bromoethanesulfonate (NaBES). Subsequently, these derivatives were used as reducing and capping agents for silver nanoparticles in a microwave-assisted reaction. The formed silver-chitosan core-shell particles were further surveyed in terms of their anticoagulant action by different coagulation assays focusing on the inhibition of either thrombin or cofactor Xa. Results: In-depth characterization revealed a sulfoalkylation of chitosan mainly on its sterically favored O6-position. Moreover, comparably high average degrees of substitution with sulfoethyl groups (DSSE) of up to 1.05 were realized in reactions with NaBES. The harsh reaction conditions led to significant chain degradation and consequently, SECS exhibits masses of

The interaction between water protons and suitable quadrupolar nuclei (QN) can lead to quadrupole relaxation enhancement (QRE) of proton spins, provided the resonance condition between both spin transitions is fulfilled. This effect could be utilized as a frequency selective mechanism in novel, responsive T1 shortening contrast agents (CAs) for magnetic resonance imaging (MRI). In particular, the proposed contrast mechanism depends on the applied external flux density—a property that can be exploited by special field-cycling MRI scanners. For the design of efficient CA molecules, exhibiting narrow and pronounced peaks in the proton T1 relaxation dispersion, the nuclear quadrupole resonance (NQR) properties, as well as the spin dynamics of the system QN−1H, have to be well understood and characterized for the compounds in question. In particular, the energy-level structure of the QN is a central determinant for the static flux densities at which the contrast enhancement appears. The energy levels depend both on the QN and the electronic environment, i.e., the chemical bonding structure in the CA molecule. In this work, the NQR properties of a family of promising organometallic compounds containing 209Bi as QN have been characterized. Important factors like temperature, chemical structure, and chemical environment have been considered by NQR spectroscopy and abinitio quantum chemistry calculations. The investigated Bi-aryl compounds turned out to fulfill several crucial requirements: NQR transition frequency range applicable to clinical 1.5- and 3T MRI systems, low temperature dependency, low toxicity, and tunability in frequency by chemical modification.

For this study, a paper impregnated with silver nanoparticles (AgNPs) was prepared. To prepare the substrates, aqueous suspensions of pulp fines, a side product from the paper production, were mixed with AgNP suspensions. The nanoparticle (NP) synthesis was then carried out via laser ablation of pure Ag in water. After the sheet formation process, the leaching of the AgNPs was determined to be low while the sheets exhibited antimicrobial activity toward Escherichia coli (E. coli).

Quadrupole relaxation enhancement (QRE) has been suggested as the key mechanism for a novel class of field-selective, potentially responsive magnetic resonance imaging contrast agents. In previous publications, QRE has been confirmed for solid compounds containing Bi-209 as the quadrupolar nucleus (QN). For QRE to be effective in aqueous dispersions, several conditions must be met, i.e. high transition probability of the QN at the H-1 Larmor frequency, water exchange with the bulk and comparatively slow motion of the Bi-carrying particles. In this paper, the potential influence of structural order within the compounds (crystallinity') on QRE was studied by nuclear quadrupole resonance (NQR) spectroscopy in one crystalline and two amorphous preparations of Triphenylbismuth (BiPh3). The amorphous preparations comprised (1) a shock-frozen melt and (2) a granulate of polystyrene which contained homogeneously distributed BiPh3 after common dissolution in THF and subsequent evaporation of the solvent. In contrast to the crystalline powder which exhibits strong, narrow NQR peaks the amorphous preparations did not reveal any NQR signals above the noise floor. From these findings, we conclude that the amorphous state leads to a significant spectral peak broadening and that for efficient QRE in potential contrast agents structures with a high degree of order (near crystalline) are required.

An elegant way for the controlled production of either cellulose fibers or hollow half spheres from trimethylsilyl cellulose (TMSC) via needleless electrospinning is reported. For this purpose trimethylsilyl celluloses (DS: 2.6–2.7) have been synthesized from three different cellulose sources, namely spruce pulp, AVICEL, and a viscose pulp. While TMSC from AVICEL is hardly processable via electrospinning, the use of viscose pulps leads to hollow semi spheres, whereas the spruce pulp based TMSC yields fibrous networks. The approach takes advantage of different degrees of molecular entanglements caused by differences in origin and molecular weight of the cellulosic material. These investigations may pave the way for further use of electrospun materials made from TMSC in, e.g., sensor devices.

As already briefly indicated in the first sections of this book, polysaccharides and here particularly cellulose, have been used from the very beginning of the battery age. In principle, either the native polysaccharide or modifications thereof can be used for battery applications. Alternatively, polysaccharides can be converted into carbonaceous materials.

Polymer-based biomaterials particularly polycaprolactone (PCL) are one of the most promising substrates for tissue engineering. The surface chemistry of these materials plays a major role since it governs protein adsorption, cell adhesion, viability, degradation, and biocompatibility in the first place. This study correlates the interaction of the most abundant serum proteins (albumin, immunoglobulins, fibrinogen) with the surface properties of PCL and its influence on the morphology and metabolic activity of primary human arterial endothelial cells that are seeded on the materials. Prior to that, thin films of PCL are manufactured by spin-coating and characterized in detail. A quartz crystal microbalance with dissipation (QCM-D), a multiparameter surface plasmon resonance spectroscopy instrument (MP-SPR), wettability data, and atomic force microscopy are combined to elucidate the pH-dependent protein adsorption on the PCL substrates. Primary endothelial cells are cultured on the protein modified polymer, and conclusions are drawn on the significant impact of type and form of proteins coatings on cell morphology and metabolic activity.

Small angle X-ray scattering (SAXS) is employed to characterize the inner structure and shape of aqueous nanocrystalline cellulose suspensions using the generalized indirect Fourier transformation (GIFT). The use of the GIFT approach provides a single fitting procedure for the determination of intra- and interparticle interactions due to a simultaneous treatment of the form factor P(q) and the structure factor S(q). Moreover, GIFT allows for the determination of particle charges and polydispersity indices. As test material, aqueous nanocrystalline cellulose suspensions (aNCS) prepared by the H2SO4 route have been investigated and characterized (SAXS, dynamic light scattering, zeta potential).

The adsorption behavior of cellulose-4-[ N -methylammonium]butyrate chloride (CMABC) on two hydrophilic substrates is studied, namely nanometric cellulose model thin films and silicon dioxide substrates. The adsorption is quantified in dependence of electrolyte concentration and pH value using a quartz crystal microbalance with dissipation (QCM-D). In case of CMABC, at high ionic strengths (25–100 mM NaCl) high adsorption is observed at pH 7 (Δ f 3 : −15 to −17 Hz) while at lower ionic strengths (1–10 mM) less CMABC (Δ f 3 : −2 to −12 Hz) is deposited on the cellulose surfaces as indicated by the frequency changes using QCM-D. A change in pH value from 7 to 8 reveals an increase in adsorption. Atomic force microscopy shows that the coating of cellulose thin films with CMABC changes the morphology from a fibrillar to a particle like structure on the surface. The surface wettability with water increases with an increasing amount of CMABC on the surface compared to neat cellulose model films. At lower pH values (3 and 5), CMABC does not adsorb onto the cellulose model thin films. XPS is used to validate the results and to determine the nitrogen content of the surfaces. In addition, adsorption of CMABC onto another hydrophilic and negatively charged substrate, silicon dioxide coated quartz crystals, cannot be detected at different pH values and electrolyte concentrations as proven by QCM-D.

In many areas of science and technology, patterned films and surfaces play a key role in engineering and development of advanced materials. Here, we introduce a new generic technique for the fabrication of polysaccharide nano-structures via focused electron beam induced conversion (FEBIC). For the proof of principle, organosoluble trimethylsilyl-cellulose (TMSC) thin films have been deposited by spin coating on SiO2 / Si and exposed to a nano-sized electron beam. It turns out that in the exposed areas an electron induced desilylation reaction takes place converting soluble TMSC to rather insoluble cellulose. After removal of the unexposed TMSC areas, structured cellulose patterns remain on the surface with FWHM line widths down to 70 nm. Systematic FEBIC parameter sweeps reveal a generally electron dose dependent behavior with three working regimes: incomplete conversion, ideal doses and over exposure. Direct (FT-IR) and indirect chemical analyses (enzymatic degradation) confirmed the cellulosic character of ideally converted areas. These investigations are complemented by a theoretical model which suggests a two-step reaction process by means of TMSC → cellulose and cellulose → non-cellulose material conversion in excellent agreement with experimental data. The extracted, individual reaction rates allowed the derivation of design rules for FEBIC parameters towards highest conversion efficiencies and highest lateral resolution.

In this contribution, we explore the interaction of lignocellulosics and proteins aiming at a better understanding of their synergistic role in natural systems. In particular, the manufacturing and characterization of amphiphilic bicomponent thin films composed of hydrophilic cellulose and a hydrophobic lignin ester in different ratios is presented which may act as a very simplified model for real systems. Besides detailed characterizations of the films and mechanisms to explain their formation, nonspecific protein adsorption using bovine serum albumin (BSA) onto the films was studied using a quartz crystal microbalance with dissipation (QCM-D). As it turns out, the rather low nonspecific protein adsorption of BSA on cellulose is further reduced when these hydrophobic lignins are incorporated into the films. The lignin ester acts in these blend films as sacrificial component, probably via an emulsification mechanism. Additionally, the amphiphilicity of the films may prevent the adsorption of BSA as well. Although there are some indications, it remains unclear whether any kind of protein interactions in such systems are of specific nature.

Two different lithographic techniques for the patterning of thin biopolymer films are developed. The first method is based on using a microstructured elastomeric mold for the structuring of thin films of regenerated cellulose. The thin films are manufactured by spin-coating of trimethylsilyl cellulose (TMSC) and subsequent regeneration. The microchannels formed by the mold and the cellulose film are filled with a cellulase solution by capillary action. In the areas exposed to the enzyme solution, the cellulose film is digested, whereas the area in contact with the mold is protected from the enzymatic activity. Optical thickness measurements, atomic force microscopy and fluorescent staining confirm a successful patterning of cellulose on several substrates by this method. The second method is based on the structured regeneration of thin TMSC films. TMSC surfaces are protected with metal masks and exposed to vapors of hydrochloric acid. These treatments result in hydrophilic cellulose structures surrounded by hydrophobic TMSC with differing physicochemical properties. Treatments of the obtained structures with cellulases allow the selective removal of pure cellulose, whereas a TMSC pattern remains on the surface. These TMSC can be regenerated back to pure cellulose by treatments with vapors of hydrochloric acid. The developed methods allow the effective fabrication of micropatterned biopolymer thin films suitable for further functionalization and application in, e.g., bioanalytical devices. This is shown by the immobilization and detection of single-stranded DNA on structured cellulose surfaces. Owing to the versatility of both patterning approaches the methods can be further extended to other combinations of substrates and enzymes.

The conversion of trimethylsilyl cellulose (TMSC) to cellulose films via acid vapor hydrolysis is investigated at the gas solid interface in situ, in real time and under ambient conditions using the QCM-D technique. For this purpose, a permanent flow of gaseous HCl is employed which reacts with TMSC spun on QCM sensors to form cellulose films. The kinetics behind this reaction is elucidated and reveals first order. This desilylation reaction proceeds via a fast first phase ( k = 3.01 × 10 −3 s −1 ) and a second slower phase ( k = 6.29 × 10 −5 s −1 ) where less accessible silyl groups are cleaved off. Besides kinetics, film thicknesses have been determined using the QCM method. Moreover, the influence of the acid concentration on the kinetics and layer thickness was studied. A comparison between the materials synthesized in the QCM chamber with those obtained by classical vapor phase hydrolysis does not show any differences in the surface characteristics and composition as proven by X-ray photoelectron spectroscopy, atomic force microscopy, and wettability studies.

The formation of t-butyl substituted polyhedral silsesquioxanes (POSS) starting from the corresponding silanetriol is reported. Several intermediates involved in this complex condensation process could be identified spectroscopically. In addition, the initial condensation intermediate t-Bu(2)Si(2)O(OH)(4), as well as t-Bu(6)Si(6)O(9) and t-Bu(7)Si(7)O(9)(OH)(3), could be characterized by X-ray crystallography. Owing to the high crystal quality it was possible to experimentally determine the geometric parameters of the unusual cyclic hydrogen bond network in a dimeric POSS trisilanol for the first time. Furthermore, we investigated the structural changes concomitant with dimer formation/dissociation of the t-butyl substituted POSS trisilanol and its methyl analogue.

The first gas phase structure of a silanetriol, tert-butylsilane-triol [(t)BuSi(OH)(3)], determined by gas electron diffraction (GED), is reported. Quantum chemical calculations have been performed to elucidate potential intermolecular interactions between silanetriol molecules in the gas phase. The results are set into contrast to solid state structures of (t)BuSi(OH)(3) and related compounds.

The use of cationic biopolymer surfaces for high protein binding affinity matrices is described. As model proteins, fluorescently labeled bovine serum albumins (FITC-BSA, TRITC-BSA) have been employed. The amount of proteins on such cationically rendered surfaces was quantified by QCM-D. In addition, flexible, transparent, patterned COP slides have been prepared and loaded with proteins ranging from 15 pM to 15 μM TRITC-BSA.

Owing to steric congestion, the phosphane unit within the title compound is dislocated from the central position which is associated with a difference in the PCC angles of 20.3(2)° and a compression of the Cl bond distance of the chlorine atom involved in this repulsive interaction. Copyright © 2006 John Wiley & Sons, Ltd.

Relativistic effects in triphenylbismuth have been investigated using a combined experimental and theoretical approach. The influence of these effects on the molecular structure (determined by gas electron diffraction) has been evaluated by means of quantum chemical calculations which consider scalar-relativistic and relativistic effects causing electronic spin-orbit coupling. Besides the molecular structure, different types of spectroscopic techniques (IR, NMR, UV-vis) have been applied and their results have been set in contrast with the results derived from quantum chemical calculations.

The preparation of water vapor barrier coatings composed of polyelectrolyte/clay multilayers using the layer-by-layer technique is reported. The suitability of different synthetic and renewable polyelectrolytes for the preparation of barrier coatings in combination with montmorillonite (MMT) platelets as well as the influence of the ionic strength and the number of bilayers on the coating performance was investigated. Highly hydrophilic and permeable cellulose films were used as substrate for determining the influence of the coatings on the water vapor transmission rate (WVTR). Improved barrier properties were realized by the use of polyethylene imine (PEI) or 2-hydroxy-3-trimethylammonium propyl chloride starch (HPMA starch) in combination with MMT. After the application of only 5 bilayers of PEI and MMT (thickness ∼40 nm) on each side of the cellulose film, the WVTR was significantly reduced. By the deposition of 40 PEI/MMT bilayers, the WVTR transmission rate was reduced by 68%. However, HPMA starch containing coatings led to vapor transmission reduction of up to 32% at the same number of coating steps. A strong correlation between the barrier properties of the coatings and the layer thickness was observed. The barrier properties of the coatings could be increased using higher ionic strengths. These results represent unprecedented water vapor barrier properties for coatings prepared from hydrophilic materials.

The synthesis of a series of m-terphenyl-substituted tetrafluorosilicates with different cations (Na(+), K(+), Rb(+), Cs(+), Ag(+), Tl(+)) is described and the interactions between the anion and cation are investigated in the solid, solution, and gas states by using multinuclear NMR spectroscopy, X-ray diffraction, and ion cyclotron resonance Fourier-transform mass spectrometry (ICR-FT-MS). In solution, heteronuclear NMR spectroscopy parameters show only limited sensitivity to the nature of the cation, which furthermore can be affected by solvent effects. More pronounced effects are observed in the structural data obtained from X-ray diffraction studies, which are in good agreement with experimental gas-phase data from ESIMS. ESIMS also reveals the existence of dimeric species of the type [M(DmpSiF(4))(2)](-) (Dmp = 2,6-dimesitylphenyl), the stability of which was determined by normalized collision energy experiments.