Achieving a sustainable foam production requires a complete substitution of synthetic components with natural and renewable alternatives, as well as development of an environment-friendly production process. This work demonstrates a synergetic combination of heat-treated beta-lactoglobulin proteins and cellulose nanofibrils (CNFs) to create fully bio-based and highly-stable wet foams. Furthermore, a gradual reduction in the pH, enabled oven-drying of the wet foams without any major structural collapse of the foam, resulting in the preparation of lightweight solid foams with the density of 10.2 kg.m(-3). First, the foaming behavior of heat-treated beta-lactoglobulin systems (HBSs) containing amyloid nanofibrils (ANFs) and non-converted peptides was investigated at different pHs. Subsequently, the HBS foams were stabilized using CNFs, followed by a gradual acidification of the system to a final pH of 4.5. To gain a deeper understanding of the stabilization mechanism of the foam, the interactions between the foam's components, their positioning in the foam structure, and the viscoelasticity of the fibrillar network were investigated using quartz crystal microgravimetry, confocal microscopy and rheology. The analysis of the obtained data suggests that the stability of the foams was associated with the accumulation of CNFs and ANFs at the air-water interface, and that the concomitant formation of an intertwined network surrounding the air bubbles. This together resulted in a significant decrease in drainage rate of the liquid in the foam lamellae, bubble coarsening and bubble coalescence within the foams. The results also show that the major surface-active component participating in the creation of the foam is the free peptide left in solution after the formation of the ANFs. A slow reduction in pH to 4.5 lead to further gelation of the fibrillar network and an improved storage modulus of the foam lamellae. This resulted in a strong coherent structure that could withstand oven-drying without collapse. The density, porosity, microstructure and compressive mechanical properties of such prepared dry foams were assessed. Overall, the results demonstrate the potential of HBSs to replace synthetic surfactants and outlines a sustainable preparation protocol for the preparation of light-weight porous composite structures of ANFs and CNFs.

The present thesis explores the utilization of spray coating for the sustainable fabrication of cellulose-based organic electronics in the framework of four different studies. The scope of this work is to contribute to the ongoing green transformation of our society in the context of industrial processing, responsible production, and clean energy. In this regard, spray coating was applied as a low-cost, fast, and industrially relevant technique for both the production as well as the quality enhancement of functional organic polymer films. In addition to that, wood-based nanocellulose, a non-toxic and biodegradable polymer, was used to replace synthetic polymers as transparent, flexible matrix- and substrate material, and as dispersing agent for the fabrication of highly conductive electrodes. Finally, spray solvents were evaluated regarding their sustainability, industrial fitness, and thus suitability for the large-scale production of organic electronics. In the course of this, various kinds of functional, hybrid organic films and foils were fabricated. Their properties were correlated with their respective structure and morphology, with a special focus on surface-sensitive analysis techniques, namely grazing incidence X-ray scattering, atomic force microscopy, scanning electron microscopy, and sheet resistance measurements.

Cellulose is a natural polymer with great properties such as high optical transparency and mechanical strength, flexibility, and biodegradability. Hence, cellulose-based foils are suitable for the replacement of synthetic polymers as substrate materials in organic electronics. This article reports the fabrication of ultrathin, free-standing cellulose foils by spraying aqueous 2,2,6,6-tetramethylpiperidine-1-oxyl-nanocellulose (TEMPO) fibrils ink layer-by-layer on a hot substrate using a movable spray nozzle. The resulting foils are only 2 ± 1 µm in thickness with an average basis weight of 1.9 g m−2, which ranges in the same scale as the world's thinnest paper. The suitability of these ultra-thin nanocellulose foils as a sustainable substrate material for organic electronic applications is demonstrated by testing the foils resistance against organic solvents. Furthermore, silver nanowires (AgNWs) and the blend poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) are integrated into the foils, and the foils are molded into 3D paper structures in order to create conductive, paper-based building blocks for organic electronics.

In times of climate change and resource scarcity, researchers are aiming to find sustainable alternatives to synthetic polymers for the fabrication of biodegradable, eco-friendly, and, at the same time, high-performance materials. Nanocomposites have the ability to combine several favorable properties of different materials in a single device. Here, we evaluate the suitability of two kinds of inks containing silver nanowires for the fast, facile, and industrial-relevant fabrication of two different types of cellulose-based silver nanowire electrodes via layer-by-layer spray deposition only. The Type I electrode has a layered structure, which is composed of a network of silver nanowires sprayed on top of a cellulose nanofibrils layer, while the Type II electrode consists of a homogeneous mixture of silver nanowires and cellulose nanofibrils. A correlation between the surface structure, conductivity, and transparency of both types of electrodes is established. We use the Haacke figure of merit for transparent electrode materials to demonstrate the favorable influence of cellulose nanofibrils in the spray ink by identifying Type II as the electrode with the lowest sheet resistance (minimum 5 ± 0.04 Ω/sq), while at the same time having a lower surface roughness and shorter fabrication time than Type I. Finally, we prove the mechanical stability of the Type II electrode by bending tests and its long-time stability under ambient conditions. The results demonstrate that the mixed spray ink of silver nanowires and cellulose nanofibrils is perfectly suitable for the fast fabrication of highly conductive organic nanoelectronics on an industrial scale.

As the quest for more sustainable and environmentally friendly materials has increased in the last decades, cellulose nanofibrils (CNFs), abundant in nature, have proven their capabilities as building blocks to create strong and stiff filaments. Experiments have been conducted to characterize CNFs with a rheo-optical flow-stop technique to study the Brownian dynamics through the CNFs’ birefringence decay after stop. This paper aims to predict the initial relaxation of birefringence using Principal Component Analysis (PCA) and Long Short-Term Memory (LSTM) networks. By reducing the dimensionality of the data frame features, we can plot the principal components (PCs) that retain most of the information and treat them as time series. We employ LSTM by training with the data before the flow stops and predicting the behavior afterward. Consequently, we reconstruct the data frames from the obtained predictions and compare them to the original data.

Cellulose nanofibrils (CNFs) can be used as building blocks for future sustainable materials including strong and stiff filaments. The goal of this paper is to introduce a data analysis of flow-induced birefringence experiments by means of unsupervised learning techniques. By reducing the dimensionality of the data with Principal Component Analysis (PCA) we are able to exploit information for the different cellulose materials at several concentrations and compare them to each other. Our approach aims at classifying the CNF materials at different concentrations by applying unsupervised machine learning algorithms, like k-means and Gaussian Mixture Models (GMMs). Finally, we analyze the autocorrelation function (ACF) and the partial autocorrelation function (PACF) of the first principal component, detecting seasonality in lower concentrations. The focus is given to the initial relaxation of birefringence after the flow is stopped to have a better understanding of the Brownian dynamics for the given materials and concentrations.

Our method can be used to distinguish the different materials at specific concentrations and could help to identify possible advantages and drawbacks of one material over the other. 

Optically responsive materials are present in everyday life, from screens to sensors. However, fabricating large-area, fossil-free materials for functional biocompatible applications is still a challenge today. Nanocelluloses from various sources, such as wood, can provide biocompatibility and are emerging candidates for templating organic optoelectronics. Silver (Ag) in its nanoscale form shows excellent optical properties. Herein, we combine both materials using thin-film large-area spray-coating to study the fabrication of optical response applications. We characterize the Ag nanoparticle formation by X-ray scattering and UV-vis spectroscopy in situ during growth on the nanocellulose template. The morphology and optical properties of the nanocellulose film are compared to the rigid reference surface SiO2. Our results clearly show the potential to tailor the energy band gap of the resulting hybrid material.

Nanostructured materials are difficult to prepare rapidly and at large scale. Melt-processed polymer-clay nanocomposites are an exception, but the clay content is typically below 5 wt%. An approach for manufacturing of microfibrillated cellulose (MFC)/kaolinite nanocomposites is here demonstrated in pilot-scale by continuous production of hybrid nanopaper structures with thickness of around 100 μm. The colloidal nature of MFC suspensions disintegrated from chemical wood fiber pulp offers the possibility to add kaolinite clay platelet particles of nanoscale thickness. For initial lab scale optimization purposes, nanocomposite processing (dewatering, small particle retention etc) and characterization (mechanical properties, density etc) were investigated using a sheet former (Rapid Köthen). This was followed by a continuous fabrication of composite paper structures using a pilot-scale web former. Nanocomposite morphology was assessed by scanning electron microscopy (SEM). Mechanical properties were measured in uniaxial tension. The fire retardancy was evaluated by cone calorimetry. Inorganic hybrid composites with high content of in-plane oriented nanocellulose, nanoclay and wood fibers were successfully produced at pilot scale. Potential applications include fire retardant paperboard for semi structural applications.

Silver nanoparticles (AgNPs) and AgNP-based composite materials have attracted growing interest due to their structure-dependent optical, electrical, catalytic, and stimuli-responsive properties. For practical applications, polymeric materials are often combined with AgNPs to provide flexibility and offer a scaffold for homogenous distribution of the AgNPs. However, the control over the assembly process of AgNPs on polymeric substrates remains a big challenge. Herein, we report the fabrication of AgNP/cellulose nanofibril (CNF) thin films via layer-by-layer (LBL) spray-coating. The morphology and self-assembly of AgNPs with increasing number of spray cycles are characterized by atomic force microscopy (AFM), grazing-incidence small-angle X-ray scattering (GISAXS), and grazing-incidence wide-angle X-ray scattering (GIWAXS). We deduce that an individual AgNP (radius = 15 +/- 3 nm) is composed of multiple nanocrystallites (diameter = 2.4 +/- 0.9 nm). Our results suggest that AgNPs are assembled into large agglomerates on SiO2 substrates during spray-coating, which is disadvantageous for AgNP functionalization. However, the incorporation of CNF substrates contributes to a more uniform distribution of AgNP agglomerates and individual AgNPs by its network structure and by absorbing the partially dissolved AgNP agglomerates. Furthermore, we demonstrate that the spray-coating of the AgNP/CNF mixture results in similar topography and agglomeration patterns of AgNPs compared to depositing AgNPs onto a precoated CNF thin film. Contact-angle measurements and UV/vis spectroscopy suggest that the deposition of AgNPs onto or within CNFs could increase the hydrophilicity of AgNP-containing surfaces and the localized surface plasmon resonance (LSPR) intensity of AgNP compared to AgNPs sprayed on SiO(2 )substrates, suggesting their potential applications in antifouling coatings or label-free biosensors. Thereby, our approach provides a platform for a facile and scalable production of AgNP/CNF films with a low agglomeration rate by two different methods as follows: (1) multistep layer-by-layer (LBL) spray-coating and (2) direct spray-coating of the AgNP/CNF mixture. We also demonstrate the ability of CNFs as a flexible framework for directing the uniform assembly of AgNPs with tailorable wettability and plasmonic properties.

Protein nanofibrils (PNFs) formed from renewable sources are capable of forming highly hierarchical structures that have potential for use in advanced materials and food textures. Hydrolyzing proteins under acidic and heated conditions results in β-sheetrich fibrils, which are known as PNFs. Depending on the protein source, concentration, and post-treatment, the fibrils’ morphology and length can vary significantly. At high concentrations whey protein forms curved and short PNFs, while at low concentrations, long and straight PNFs are obtained. This variability in structure influences the ability of PNFs to assemble hierarchically. Additionally, plant proteins like mung bean proteins can produce PNFs that have unique properties, such as improved foaming. With hydrodynamic assembly methods like microfluidics, a well-aligned microfiber can be created from these PNFs, mimicking the natural fiber formation process seen in materials like silk. In this study, experiments and numerical methods are combined to investigate the flow behavior and alignment of various PNFs using small-angle X-ray scattering (SAXS). Developing new, sustainable materials with enhanced properties can be achieved by understanding the influence of PNF morphology on hydrodynamic alignment and assembly.

Understanding wood’s complex nanostructure and interactions inspires the development of bio-mimetic engineering materials with similar structural and performance characteristics. Their strength, stiffness, toughness, and resilience enable them to resist tensions more effectively and adapt to varying mechanical demands, deriving from the alignment of cellulose nanofibers (CNFs) and the cohesion between them. We have utilized a composite dispersion of CNF and a dendritic polyampholyte, Helux, to: (i) assess the simultaneous effect of alignment and interactions on mechanical properties, and (ii) spin functional tough filaments. Amidation chemistry offers the opportunity for post-functionalization of filaments through Helux-accessible amines, which also enhance mechanical properties via covalent cross-linking at elevated temperatures. Composite filaments exhibited 60% higher ultimate strength and roughly five times higher toughness despite lower fibril alignment (as evidenced by wide-angle X-ray scattering) and a corresponding lower elastic modulus in the presence of Helux. We further investigate the trade-off between CNF alignment and mechanical properties using our desktop polarized optical microscopy (POM) flow-stop technique and in-situ small-angle X-ray scattering (SAXS) in conjunction with its digital twin. A lower degree of alignment in composite dispersions is attributed to faster fibril dynamics and higher rotary diffusion in the presence of negatively charged Helux molecules, facilitating de-alignment. However, Helux can ionically interact with multiple fibrils and physically link them together, forming a tougher and stronger 3D network with a denser morphology and fewer voids, owing to its multi-valent nature. Indeed, there is an affinity between these interactions and those formed between cellulose and lignin/hemicellulose in wood.

Sustainable development requires the development of lightweight, sustainable structural materials with excellent mechanical properties derived from renewable resources. This study investigates the fabrication of lignocellulose nanofibrils (LCNFs) from TEMPO-oxidized unbleached pulps by taking advantage of the lignin retention properties. Due to the presence of lignin, unbleached pulp provides hydrophobic and binding properties that aren’t found in traditional nanofibrils (CNFs) obtained from fully-bleached pulp. Microfluidic spinning techniques were employed to produce highly ordered LCNF-based filaments, with an emphasis on two types of filament: K2 (lower lignin content) and K96 (higher lignin content). In addition to environmental benefits, enhancing alignment and mechanical performance, lignin promotes filament structural order and integrity. It is a promising route for producing strong, high-performance filaments from wood fiber raw materials, reducing their environmental footprint and contributing to the development of next-generation sustainable products.

We here explore confinement-induced assembly of whey protein nanofibrils (PNFs) into microscale fibers using micro-focused synchrotron X-ray scattering. Solvent evaporation aligns the PNFs into anisotropic fibers and the process is followed in situ by scattering experiments in a droplet of PNF dispersion. We find an optimal temperature at which the order of the protein fiber has a maximum, suggesting that the degree of order results from a balance between the time scales of the forced alignment and the rotational diffusion of the fibrils. Moreover, we observe that the assembly process depends on the nano-scale morphology of the PNFs. Stiff PNFs with a persistence length in the micrometer scale are aligned at the air-water interface and the anisotropy gradually decrease towards the center of the droplet. Marangoni flows often increase entanglements toward the center, leading to complex patterns in the droplet. Flexible fibrils with a short persistence length (< 100 nm) tends to align uniformly throughout the droplet, possibly due to stronger local entanglements. Straight PNFs form smaller clusters with shorter inter-cluster distances due to their tight packing and consistent linear structure. In contrast, curved PNFs form intricate networks with larger characteristic distances and more varied structures because of their flexibility and adaptability.

The need for multifunctional, robust, reusable, and high-flux filters is a constant challenge for sustainable water treatment. In this work, fully biobased and biodegradable water purification filters were developed and processed by the means of three-dimensional (3D) printing, more specifically by fused deposition modelling (FDM). The polylactic acid (PLA) – based composites reinforced with homogenously dispersed TEMPO-oxidized cellulose nanofibers (TCNF) or chitin nanofibers (ChNF) were prepared within a four-step process; i. melt blending, ii. thermally induced phase separation (TIPS) pelletization method, iii. freeze drying and iv. single-screw extrusion to 3D printing filaments. The monolithic, biocomposite filters were 3D printed in cylindrical as well as hourglass geometries with varying, multiscale pore architectures. The filters were designed to control the contact time between filter's active surfaces and contaminants, tailoring their permeance. All printed filters exhibited high print quality and high water throughput as well as enhanced mechanical properties, compared to pristine PLA filters. The improved toughness values of the biocomposite filters clearly indicate the reinforcing effect of the homogenously dispersed nanofibers (NFs). The homogenous dispersion is attributed to the TIPS method. The NFs effect is also reflected in the adsorption capacity of the filters towards copper ions, which was shown to be as high as 234 and 208 mg/gNF for TCNF and ChNF reinforced filters, respectively, compared to just 4 mg/g for the pure PLA filters. Moreover, the biocomposite-based filters showed higher potential for removal of microplastics from laundry effluent water when compared to pure PLA filters with maximum separation efficiency of 54 % and 35 % for TCNF/PLA and ChNF/PLA filters, respectively compared to 26 % for pure PLA filters, all that while maintaining their high permeance. The combination of environmentally friendly materials with a cost and time-effective technology such as FDM allows the development of customized water filtration systems, which can be easily adapted in the areas most affected by the inaccessibility of clean water.

The nanostructure, primarily particle orientation, controls mechanical and functional (e.g., mouthfeel, cell compatibility, optical, morphing) properties when macroscopic materials are assembled from nanofibrils. Understanding and controlling the nanostructure is therefore an important key for the continued development of nanotechnology. We merge recent developments in the assembly of biological nanofibrils, X-ray diffraction orientation measurements, and computational fluid dynamics of complex flows. The result is a digital twin, which reveals the complete particle orientation in complex and transient flow situations, in particular the local alignment and spatial variation of the orientation distributions of different length fractions, both along the process and over a specific cross section. The methodology forms a necessary foundation for analysis and optimization of assembly involving anisotropic particles. Furthermore, it provides a bridge between advanced in operandi measurements of nanostructures and phenomena such as transitions between liquid crystal states and in silico studies of particle interactions and agglomeration.

We report a combined experimental and numerical investigation to decipher and delineate the role of fluid properties, flow parameters, and geometries on the dynamics of viscous thread formation in microchannels with miscible solvents. A methodological analysis based on the evolution of viscous threads unveils the significance of effective interfacial tension (EIT) induced by the virtue of concentration gradients between the non-equilibrium miscible fluid pair colloidal dispersions and their own solvent.  Functional scaling relationships developed with dimensionless capillary and Weber numbers, together with thread quantities thread detachment length, and thread width, shed light on the complex interplay of hydrodynamic effects and viscous microflow processes. The detachment of viscous threads inside microchannels is governed by the unified hydrodynamic effects of inertia, capillary, and viscous stresses in contrast to the natural phenomenon of self-lubrication,  bringing new insights to the physical phenomena involved in the confined microsystems. Exploiting the experimentally measured thread quantities, the scaling laws are practically applied to estimate the inherent fluid properties such as EIT between two inhomogeneous miscible fluids, and the fluid viscosities. In addition, the cross-sectional aspect ratio of the channels is varied numerically in conjunction with the converging shaped sections.  For specified flow rates and given rheologies of the fluids,  a flow-focusing configuration producing the shortest thread detachment length, and a longer region of strain rate along the centreline is identified. Overall, this work provides a consolidated description of the effect of fluid properties, flow parameters, and geometry on the formation of miscible viscous threads in microchannel flows. 

Hybrid plasmonic nanostructures have gained enormous attention in a variety of optoelectronic devices due to their surface plasmon resonance properties. Self-assembled hybrid metal/quantum dot (QD) architectures offer a means of coupling the properties of plasmonics and QDs to photodetectors, thereby modifying their functionality. The arrangement and localization of hybrid nanostructures have an impact on exciton trapping and light harvesting. Here, we present a hybrid structure consisting of self-assembled gold nanospheres (Au NSs) embedded in a solid matrix of PbS QDs for mapping the interface structures and the motion of charge carriers. Grazing-incidence small-angle X-ray scattering is utilized to analyze the localization and spacing of the Au NSs within the hybrid structure. Furthermore, by correlating the morphology of the Au NSs in the hybrid structure with the corresponding differences observed in the performance of photodetectors, we are able to determine the impact of interface charge carrier dynamics in the coupling structure. From the perspective of architecture, our study provides insights into the performance improvement of optoelectronic devices.

Point-of-need devices perform analytical tests that help inform decisions where they are needed, away from modern lab infrastructure, be it in-field or in resource-poor settings. They have many applications, including veterinary medicine, agriculture, food safety, environmental monitoring, and forensics. In medical diagnostics, such devices are called point-of-care tests, and they could help combat societal challenges such as the spread of epidemic diseases and providing adequate healthcare in developing countries. Point-of-care devices could also be wearable to non-invasively monitor body fluids such as sweat or urine from the patient. Ideal point-of-care devices conform with the REASSURED criteria, that they should be Real-time connected, Easy to collect samples, Affordable, Sensitive, Specific, User-friendly, Rapid, robust, Equipment-free, environmentally friendly, and Deliverable to the end user.

We have here developed Point-of-need devices based on textiles and Printed Circuit Boards (PCBs); both well-established technologies that could offer low-cost mass production using existing industrial resources. Specifically, we have made electrochemical biosensors based on gold-coated yarn in a rolling architecture, as well as combined with wicking Coolmax® yarn acting as microfluidic channels in wearable systems, enabling advanced textile-based diagnostic devices suitable for automation or machine-stitching into fabrics. We also showed biosensors based on gold-coated PCBs that can connect to portable potentiostats for electrochemical detection and have integrated heating for isothermal nucleic acid amplification.

Thread-based microfluidics, which rely on capillary forces in threads for liquid flow, are a promising alternative to conventional microfluidics, as they can be easily integrated into wearable textile-based biosensors. We present here advanced textile-based microfluidic devices fabricated by machine stitching, using only commercially available textiles. We stitch a polyester “Coolmax®” yarn with enhanced wicking abilities into both hydrophobic fabric and hydrophobically treated stretchable fabric, that serve as non-wicking substrates. In doing so we construct textile microfluidics capable of performing a wide variety of functions, including mixing and separation in 2D and 3D configurations. Furthermore, we integrate a stitched microfluidic device into a wearable T-shirt and show that this device can collect, transport, and detect sweat from the wearer’s skin. These can also be machine-washed, making them inherently reusable. Finally, we integrate electrochemical sensors into the textile-based microfluidic devices using stitched gold-coated yarns to detect analytes in the microfluidic yarns. Our stitched textile-based microfluidic devices hold promise for wearable diagnostic applications. This novel, bottom-up fabrication using machine stitching is scalable, reproducible, low-cost, and compatible with the existing textile manufacturing industry.

Nucleic acid amplification tests (NAATs) are powerful medical diagnostic tools for point-of-care (POC) and other field applications. However, traditional methods like qquantitative PCR (qPCR) require complex, expensive equipment and trained operators, limiting their use to centralized labs. Isothermal alternatives, like Loop-mediated Isothermal Amplification (LAMP), are better adapted for POC devices. Lab-on-PCB systems have the potential to overcome the challenges faced by conventional microfabrication-based systems. This study presents a novel lab-on-PCB device for RNA amplification and electrochemical detection using reverse transcription LAMP (RT-LAMP) of SARS-CoV-2. The system consists of only two disposable PCB-based chips making it close to zero cost. One PCB is for heating and DNA amplification, while the other is for electrochemical detection using Cyclic Voltammetry with a redox-active intercalating probe. The PCB slides are connected to a compact electronic device (<10 USD) for controlling the heating and electroanalytical readout. Using this device, we achieved successful rapid (<1 hour) nucleic amplification and detection at a target concentration of 100 copies/reaction. This work represents a notable step toward developing integrated, portable NAAT devices for POC diagnostics.

The colloidal layer formation on porous materials is a crucial step for printing and applying functional coatings, which can be used to fabricate anticounterfeiting paper. The deposition of colloidal layers and subsequent thermal treatment allows for modifying the hydrophilicity of the surface of a material. In the present work, wood-based colloidal inks are applied by spray deposition on spray-deposited porous cellulose nanofibrils (CNF) films. The surface modification by thermal annealing of the fabricated colloid-cellulose hybrid thin films is investigated in terms of layering and hydrophobicity. The polymer colloids in the inks are core-shell nanoparticles with different sizes and glass transition temperatures (T-g), thus enabling different and low thermal treatment temperatures. The ratio between the core polymers, poly(sobrerol methacrylate) (PSobMA), and poly(-butyl methacrylate) (PBMA) determines the T-g and hence allows for tailoring of the T-g. The layer formation of the colloidal inks on the porous CNF layer depends on the imbibition properties of the CNF layer which is determined by their morphology. The water adhesion of the CNF layer decreases due to the deposition of the colloids and thermal treatment except for the colloids with a size smaller than the void size of the porous CNF film. In this case, the colloids are imbibed into the CNF layer when T-g of the colloids is reached and the polymer chains transit in a mobile phase. Tailored aggregate and nanoscale-embedded hybrid structures are achieved depending on the colloid properties. The imbibition of these colloids into the porous CNF films is verified with grazing incidence small-angle X-ray scattering. This study shows a route for tuning the nanoscale structure and macroscopic physicochemical properties useful for anticounterfeiting paper.

Despite perovskite solar cells (PSCs) based on a SnO2 hole-blocking layer (HBL) are achieving excellent performance, the non-perfect buried interface between the SnO2 HBL and the perovskite layer is still an obstacle in achieving further improvement in power conversion efficiency (PCE) and stability. The poor morphology with numerous defects and the energy level mismatch at the buried interface constrain the open circuit voltage and cause instability. Herein, a sputter-deposited TiOx thin film is used as a buried interface modification layer to address the aforementioned issues. Utilizing in situ grazing-incidence small-angle X-ray scattering (GISAXS) during the sputter deposition, we monitor and unveil the growth process of the TiOx thin film, identifying a 10 nm thickness optimum. The defects at the buried interface are passivated through tuning the growth, leading to a suppressed non-radiative recombination and improved PCE (from 22.19 % to 23.93 %). The evolution of the device performance and the degradation process of PSCs using operando grazing-incidence wide-angle X-ray scattering (GIWAXS) under the protocol ISOS-L-1I explains the enhanced stability introduced by the buried interface modification via a sputter-deposited TiOx thin layer. The perovskite decomposition process and the detrimental formation of PbI2 are both slowed down by the TiOx thin layer.

A multifunctional hybrid gel based on cellulose nanofibrils (CNFs) was developed by grafting on its surface stearyl acrylate (PSA) and gadolinium(III) fluoride nanoparticles (GdF3 NPs) via Cu0-mediated surface-initiated radical polymerization (SET-LRP) while encapsulating antimicrobial peptides in it. GdF3 NPs were first surface-modified with 11-phosphonoundecyl acrylate (PDA) to participate in the SET-LRP and cross-linked the grafted polymer-modified CNF. Several characterizations of the hybrid material (GdF3-PSA-CNF) were carried out, such as Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), rheology, and microscopic analyses. The grafted PSA and cross-linked GdF3 NPs created sophisticated networks in the CNF-based gel, presenting outstanding rheological properties and promising three-dimensional (3D) printability of this hybrid material (GdF3-PSA-CNF). The nanostructures of GdF3 NPs and their incorporated CNF species were characterized via small-angle X-ray scattering (SAXS). In addition, due to the unique intrinsic property of the GdF3 nanoparticles, properties for magnetic resonance imaging (MRI) of GdF3-PSA-CNF were investigated, showing the potential application as a contrast agent. Finally, the encapsulation of the antimicrobial peptides added another function to the hybrid material, evaluated by an antimicrobial test against methicillin-resistant Staphylococcus aureus (MRSA) in vitro.

Coherent X-ray imaging techniques, such as in-line holography, exploit the high brilliance provided by diffraction-limited storage rings to perform imaging sensitive to the electron density through contrast due to the phase shift, rather than conventional attenuation contrast. Thus, coherent X-ray imaging techniques enable high-sensitivity and low-dose imaging, especially for low-atomic-number (Z) chemical elements and materials with similar attenuation contrast. Here, the first implementation of in-line holography at the NanoMAX beamline is presented, which benefits from the exceptional focusing capabilities and the high brilliance provided by MAX IV, the first operational diffractionlimited storage ring up to approximately 300 eV. It is demonstrated that in-line holography at NanoMAX can provide 2D diffraction-limited images, where the achievable resolution is only limited by the 70 nm focal spot at 13 keV X-ray energy. Also, the 3D capabilities of this instrument are demonstrated by performing holotomography on a chalk sample at a mesoscale resolution of around 155 nm. It is foreseen that in-line holography will broaden the spectra of capabilities of MAX IV by providing fast 2D and 3D electron density images from mesoscale down to nanoscale resolution.

Titanium dioxide (TiO2) shows significant potential as a self-cleaning material to inactivate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and prevent virus transmission. This study provides insights into the impact of UV-A light on the photocatalytic inactivation of adsorbed SARS-CoV-2 virus-like particles (VLPs) on a TiO2 surface at the molecular and atomic levels. X-ray photoelectron spectroscopy, combined with density functional theory calculations, reveals that spike proteins can adsorb on TiO2 predominantly via their amine and amide functional groups in their amino acids blocks. We employ atomic force microscopy and grazing-incidence small-angle X-ray scattering (GISAXS) to investigate the molecular-scale morphological changes during the inactivation of VLPs on TiO2 under light irradiation. Notably, in situ measurements reveal photoinduced morphological changes of VLPs, resulting in increased particle diameters. These results suggest that the denaturation of structural proteins induced by UV irradiation and oxidation of the virus structure through photocatalytic reactions can take place on the TiO2 surface. The in situ GISAXS measurements under an N2 atmosphere reveal that the virus morphology remains intact under UV light. This provides evidence that the presence of both oxygen and UV light is necessary to initiate photocatalytic reactions on the surface and subsequently inactivate the adsorbed viruses. The chemical insights into the virus inactivation process obtained in this study contribute significantly to the development of solid materials for the inactivation of enveloped viruses.

The ability to control the structure of the wood-pulp fiber cell wall is an attractive means to obtain increased accessibility to the fiber interior, providing routes for functionalization of the fibers that support further processing and novel material concepts, e.g. improved degree of polymerization, nanofiltration as demonstrated in previous studies. It has been proposed that dynamic compression and decompression of the cellulose pulp fibers in the wet state make it possible to modify the cell wall significantly. We hypothesize that hydrostatic pressure exerted on fibers fully submerged in water will increase the accessibility of the fiber wall by penetrating the fiber through weak spots in the cell wall. To pursue this, we have developed an experimental facility that can subject wet cellulose pulp samples to a pressure pulse -10 ms long and with a peak pressure of -300 MPa. The experiment is thus specifically designed to elucidate the effect of a rapid high-pressure pulse passing through the cellulose sample and enables studies of changes in structural properties over different size ranges. Different characterization techniques, including Scanning electron microscopy, X-ray diffraction, and wide- and small-angle X-ray scattering, have been used to evaluate the material exposed to pulsed pressure. The mechanism of pressure build-up is estimated computationally to complement the results. Key findings from the experiments consider a decrease in crystallinity and changes in the surface morphology of the cellulose sample.

Studies of molecular changes in cellulose structure as a response to different physical conditions are essential for understanding the fundamental mechanisms that can be used to optimise processing conditions and contribute to improved sustainability. Cellulose strongly interacts with water, raising the question of whether it is possible to change its molecular structure by changing the physical structure and properties of the surrounding water. Previous studies have established that the hyperbaric treatment of bio-materials permanently affects molecular structure in terms of crystallinity and accessibility. The present study shows the changes in cellulose-rich pulps on the molecular level in response to static extreme-pressure conditions. This is achieved by statically compressing the pulp-water mixture up to 3 GPa pressure using a resistive-heated di-amond anvil cell (DAC). During compression, the water transforms through a phase transformation from liquid to ice VI and ice VII, inducing a permanent increase in the crystallinity of the pulp. High-pressure, cellulose, X-ray diffraction, diamond anvil cell, crystallinity, morphological changes

The ability to modify the structure of the wood-pulp fibre cell wall structure is an attractive means to obtain increased accessibility to the fibre interior and enable functionalization such as controlled drug delivery, interpenetrated networks, and selective removal of metal ions from aqueous mixtures just to mention a few examples. By changing the physical state of water, it should be possible to significantly alter the structure of the wet fibre wall, providing the possibility to perform cell wall modifications under extreme conditions. To address this challenge, we have focussed on investigating the structural development of the wet softwood kraft pulp fibre wall under high pressure (HP) conditions (up to 2 GPa). The experiments aim to clarify the effect of the HP conditions on the porosity and the accessibility of the fibre wall for treated and untreated fibres. The second goal is to observe the changes in the crystalline structure of cellulose due to HP conditions. Different characterization techniques, including Electron microscopy, X-ray diffraction, Small and wide-angle X-ray scattering, and Cross-polarized/magic angle spinning 13C-NMR, are used to characterize material that has been exposed to HP. Key findings from the experiments relate to changes in crystallinity, specific surface area, bound water content and surface morphology.

Biopolymer network dynamics play a significant role in both biological and materials science. This study focuses on the dynamics of cellulose nanofibers as a model system given their relevance to biology and nanotechnology applications. Using large-scale coarse-grained simulations with a lattice Boltzmann fluid coupling, we investigated the reptation behavior of individual nanofibers within entangled networks. Our analysis yields essential insights, proposing a scaling law for rotational diffusion, quantifying effective tube diameter, and revealing release mechanisms during reptation, spanning from rigid to semiflexible nanofibers. Additionally, we examine the onset of entanglement in relation to the nanofiber flexibility within the network. Microrheology analysis is conducted to assess macroscopic viscoelastic behavior. Importantly, our results align closely with previous experiments, validating the proposed scaling laws, effective tube diameters, and onset of entanglement. The findings provide an improved fundamental understanding of biopolymer network dynamics and guide the design of processes for advanced biobased materials. 

The structure and dynamics of networks formed by rod-shaped particles can be indirectly investigated by measuring the diffusion of spherical tracer particles. This method was used to characterize cellulose nanofibril (CNF) networks in both dispersed and arrested states, the results of which were compared with coarse-grained Brownian dynamics simulations. At a CNF concentration of 0.2 wt% a transition was observed where, below this concentration tracer diffusion is governed by the increasing macroscopic viscosity of the dispersion. Above 0.2 wt%, the diffusion of small particles (20-40 nm) remains viscosity controlled, while particles (100-500 nm) become trapped in the CNF network. Sedimentation of silica microparticles (1-5 mu m) in CNF dispersions was also determined, showing that sedimentation of larger particles is significantly affected by the presence of CNF. At concentrations of 0.2 wt%, the sedimentation velocity of 5 mu m particles was reduced by 99 % compared to pure water.

The ForMAX beamline at the MAX IV Laboratory provides multiscale and multimodal structural characterization of hierarchical materials in the nanometre to millimetre range by combining small- and wide-angle X-ray scattering with full-field microtomography. The modular design of the beamline is optimized for easy switching between different experimental modalities. The beamline has a special focus on the development of novel fibrous materials from forest resources, but it is also well suited for studies within, for example, food science and biomedical research.

The integration of silver thin films into optoelectronic devices has gained much interest due to their exceptional properties in terms of conductivity and compatibility with flexible substrates. For this type of application, ultrathin layers are desirable, because of their optical transparency. Standard direct current magnetron sputtering (DCMS) is known to lead to undesirable formation of islands at low effective film thicknesses on typical substrates like SiO2 or polystyrene (PS). Therefore, in this study, we explore high-power impulse magnetron sputtering (HiPIMS) with optional further acceleration of metal ions by biasing the substrate or an additional positive pulse (bipolar HiPIMS) for the fabrication of ultra-thin silver layers. The morphology and electrical properties of ultra-thin silver layers with selected effective thicknesses are characterized on SiO2 and PS substrates. The growth evolution of characteristic parameters is further investigated by in-situ grazing-incidence small-angle Xray scattering (GISAXS). The results show that HiPIMS deposition yields films with a higher density of clusters than DCMS leading to a percolation threshold at lower effective film thicknesses. This effect is amplified by further ion acceleration. Thus, we suggest HiPIMS as a promising technique for fabricating ultra-thin, conductive layers on organic and oxide substrates.

Cellulose fibrils are the structural backbone of plants and, if carefully liberated from biomass, a promising building block for a bio-based society. The mechanism of the mechanical release-fibrillation-is not yet understood, which hinders efficient production with the required reliable quality. One promising process for fine fibrillation and total fibrillation of cellulose is cavitation. In this study, we investigate the cavitation treatment of dissolving, enzymatically pretreated, and derivatized (TEMPO oxidized and carboxymethylated) cellulose fiber pulp by hydrodynamic and acoustic (i.e., sonication) cavitation. The derivatized fibers exhibited significant damage from the cavitation treatment, and sonication efficiently fibrillated the fibers into nanocellulose with an elementary fibril thickness. The breakage of cellulose fibers and fibrils depends on the number of cavitation treatment events. In assessing the damage to the fiber, we presume that microstreaming in the vicinity of imploding cavities breaks the fiber into fibrils, most likely by bending. A simple model showed the correlation between the fibrillation of the carboxymethylated cellulose (CMCe) fibers, the sonication power and time, and the relative size of the active zone below the sonication horn.

Multimodal in situ experiments during slot-die coating of thin films pioneer the way to kinetic studies on thin-film formation. They establish a powerful tool to understand and optimize the formation and properties of thin-film devices, e.g., solar cells, sensors, or LED films. Thin-film research benefits from time-resolved grazing-incidence wide- and small-angle x-ray scattering (GIWAXS/GISAXS) with a sub-second resolution to reveal the evolution of crystal structure, texture, and morphology during the deposition process. Simultaneously investigating optical properties by in situ photoluminescence measurements complements in-depth kinetic studies focusing on a comprehensive understanding of the triangular interdependency of processing, structure, and function for a roll-to-roll compatible, scalable thin-film deposition process. Here, we introduce a modular slot-die coater specially designed for in situ GIWAXS/GISAXS measurements and applicable to various ink systems. With a design for quick assembly, the slot-die coater permits the reproducible and comparable fabrication of thin films in the lab and at the synchrotron using the very same hardware components, as demonstrated in this work by experiments performed at Deutsches Elektronen-Synchrotron (DESY). Simultaneous to GIWAXS/GISAXS, photoluminescence measurements probe optoelectronic properties in situ during thin-film formation. An environmental chamber allows to control the atmosphere inside the coater. Modular construction and lightweight design make the coater mobile, easy to transport, quickly extendable, and adaptable to new beamline environments.

INSIGHT is a Python-based software tool for processing and reducing 2D grazing-incidence wide- and small-angle X-ray scattering (GIWAXS/GISAXS) data. It offers the geometric transformation of the 2D GIWAXS/GISAXS detector image to reciprocal space, including vectorized and parallelized pixelwise intensity correction calculations. An explicit focus on efficient data management and batch processing enables full control of large time-resolved synchrotron and laboratory data sets for a detailed analysis of kinetic GIWAXS/ GISAXS studies of thin films. It processes data acquired with arbitrarily rotated detectors and performs vertical, horizontal, azimuthal and radial cuts in reciprocal space. It further allows crystallographic indexing and GIWAXS pattern simulation, and provides various plotting and export functionalities. Customized scripting offers a one-step solution to reduce, process, analyze and export findings of large in situ and operando data sets.

A series of different technical hardwood lignin-based resins have been successfully synthesized, characterized, and utilised to produce thiol-ene thermoset polymers. Firstly, technical lignin was fractionated and allylated, whereafter it was crosslinked with a trifunctional thiol. Structural and morphological characteristics of the lignin fractions were studied by 1H NMR, 31P NMR, SEC, FTIR, DSC, TGA, and WAXS. The hardwood lignin fractions have a high content of C5-substituted OH groups. The WAXS studies on lignin fractions revealed the presence of two π-π stacking conformations, sandwiched (4.08–4.25 Å) and T-shaped (6.52–6.91 Å). The presence of lignin superstructures with distances/sizes between 10.5 and 12.8 Å was also identified. The curing reaction of the thermosets was investigated by RT-FTIR. Almost all thermosets (excepting one fraction) reached 95% of the thiol conversion in less than 17 h, revealing the enhanced reactivity of the allylated hardwood lignin samples.

The mechanical properties of the thermosets were investigated by DMA. The curing performance, as well as the final thermoset properties, have been correlated to variations in chemical composition and morphological differences of lignin fractions. The described results clearly demonstrate that technical hardwood lignins can be utilized for these applications, but also that significant differences compared to softwood lignins have to be considered for material design.