Eero Kontturi

Industrial lignin is transformed into ultramicroporous carbon enabling high-capacity low-energy CO ₂ capture in cellulose foams.

Molecular weight parameters, such as molar mass distribution (MMD), are core characteristics of polymer materials. While MMD is routinely measured by gel permeation chromatography (GPC), the procedure takes time and resources and requires specific, relatively costly instruments. Polysaccharides such as cellulose and chitin are particularly difficult to dissolve. Herein, we report on the potential of combining hyperspectral imaging (HSI) with machine learning (ML) to predict, at different length scales, the MMDs of these sparingly soluble fibrous polymers from visible-range HS images (420−730 nm) of the solid substrate. A Gaussian process regression model was trained on principal component representations of the HS cubes against MMDs measured by GPC. HCl-vapor hydrolysis served as a controlled degradation pathway that altered the degree of polymerization without detectable morphological change. Although samples appear identical to the eye and under electron microscopy, HSI captures systematic optical differences that can be empirically related to GPC-measured MMD within the investigated hydrolyzed samples. Predicted distributions matched the GPC reference, with curve RMSEs of 0.009−0.027 (native cellulose paper), 0.017−0.050 (cellulose nanopaper), and 0.016−0.029 (chitin nanopaper). The principal features of the bimodal MMD of cellulose nanopaper and the leveling-off degree of polymerization were both recovered. The workflow uses a microscope, a tunable bandpass filter, and a digital camera, completing HSI acquisition and prediction in a few minutes per sample. This approach provides a non-destructive, solvent-free complement to traditional analytical techniques. The presented case study is a proof-of-concept, calibrated against GPC reference data for the specific materials and protocols studied here. Expanding to other polymer systems would require establishing a similar chromatographic reference for each new system.

HCl pulping converts algae into paper with properties comparable to wood-based paper. Environmental impact of manufacturing is assessed and compared to relevant alternatives.

This study addresses knowledge gaps concerning interactions between barley mixed-linkage glucans (MLGs) and TEMPO-oxidized cellulose nanocrystals (TCNC), focusing on underlying physiochemical and thermodynamic principles. Combining dynamic light scattering (DLS), quartz crystal microbalance with dissipation monitoring (QCM-D), and isothermal titration calorimetry (ITC), we systematically investigated MLG solution properties, adsorption at cellulose surfaces, and thermodynamics of interaction. DLS revealed limited aqueous solubility of MLGs, with elevated temperatures promoting aggregate formation and reducing solution stability. QCM-D experiments showed that MLG forms thick hydrogel layers at cellulose interfaces and Voigt modeling confirmed temperature-dependent viscoelastic properties of the layers. Analysis of QCM-D data with van’t Hoff approach together with ITC showcased only minor enthalpic contributions and predominantly entropic interactions. Altogether, these findings clarify MLG-cellulose interconnections and interlink between solubility, interfacial behavior, and functionalities of MLG in all-polysaccharide materials architectures. Additionally, the results point towards MLG providing a hydrating layer in plant cell walls in nature.

Aqueous zinc‐ion batteries (AZIBs) offer a safe and low‐cost energy storage platform yet are plagued by interfacial instability. Here, we investigate the relationship between molecular stereoisomerism and interfacial adsorption using inositol as a model system. Theoretical calculations reveal that the hydroxyl group orientation, arrangement, and geometric compatibility from different stereoisomers dictate the molecular adsorption at the Zn interface. The resulting tilted adsorption configuration of myo‐inositol establishes a water‐deficient electric double layer that effectively suppresses interfacial side reactions, restricts lateral Zn ²⁺ diffusion, and induces preferential Zn (101) deposition. Meanwhile, myo‐inositol reorganizes the hydrogen‐bond network and replaces coordinated water, thereby optimizing Zn ²⁺ desolvation process. Consequently, the assembled Zn//Zn symmetric cell shows markedly improved cycling stability for over 4500 h at 2 mA cm ⁻² . The Zn//NaV ₃ O ₈ ·1.5H ₂ O full cell achieves excellent long‐term stability over 5000 cycles, with 0.002% capacity degradation per cycle. Pouch cells with different mass loadings operate stably without obvious capacity loss. This work elucidates how stereoisomerism governs interfacial adsorption through hydroxyl‐group arrangement, providing critical design insights for the molecular engineering of stable AZIBs.

Solid-state photosynthetic cell factories transform dissolved and atmospheric carbon into chemicals and biomass, offering a platform for the sustainable production of industrially relevant compounds. Yet, how immobilisation affects cell physiology to favour biosynthesis over growth is unclear. Here, we fabricate photosynthetic biohybrids of cellulose nanofiber (CNF) and Synechocystis sp. PCC 6803 by osmotic dehydration. Osmotic dehydration resulted in an anisotropic distribution of the cyanobacterial colonies and provided excellent light distribution during cultivation. In an engineered sucrose-secreting Synechocystis strain, quantitative proteomics showed that immobilization downregulates ribosomal proteins while upregulating sucrose-synthesis and carbon concentrating machinery, as well as a stress signature of enhanced photosystem II repair, photoprotection, and ROS detoxification. These changes are consistent with a reallocation of constrained proteome resources from growth toward product synthesis. This principle may be extendable to photosynthetic production of compounds beyond sucrose.

Aqueous zinc batteries (AZBs) face significant challenges due to the limited compatibility of Zn anodes with conventional separators, leading to dendrite growth, hydrogen evolution reaction (HER), and poor cycling stability. While separator design is crucial for optimizing battery performance, its potential remains underexplored. Commonly used glass fiber filters were not originally designed as battery separators, and their properties have a limited impact on these challenges. To address these limitations, nanochitin derived from waste shrimp shells was used to fabricate separators with varying concentrations of amine and carboxylic functional groups. This study investigates how the type and concentration of these groups influence separator properties and performance, inhibiting dendrite growth, local HER formation, and poor cycling stability. In a mild acidic electrolyte, the density of ammonium and carboxylic groups significantly affected water structure and ionic conductivity. Quasi‐elastic neutron scattering revealed that low‐functionalized chitin, particularly with only ammonium groups, promotes strongly bound water with restricted mobility, enhancing Zn plating and stripping kinetics. These separators exhibit exceptional Zn stability over 2000 h at 0.5 mA/cm ² , maintaining low overpotentials and stable polarization. Full cells of ZnǁNaV ₃ O ₈ ·1.5H ₂ O achieved over 2000 cycles at 2 A/g, demonstrating that simple, low‐functionalized nanochitin separators significantly improve AZB performance.

Binders are essential components in battery systems that maintain the electrode structure and integrity throughout cycling. The choice of binder affects processing, electrochemical behavior, and end-of-life recovery. The widely used poly(vinylidene difluoride) (PVDF) binder is increasingly scrutinized since it is a polyfluoroalkyl compound and requires processing in organic solvents like N-methyl-2-pyrrolidone. Consequently, efforts are underway to identify more sustainable options. In this work, we present chitin nanofibers (ChNFs), derived from fisheries waste, as a biobased, fluorine-free alternative that enables fully aqueous electrode fabrication. ChNFs disperse more than 90% of graphite in water without the need for auxiliary agents such as surfactants. Colloidal probe microscopy shows that adhesion between protonated ChNFs and graphite depends on pH, likely being governed by cation-π interactions. This strong affinity facilitates the remarkable dispersing capability of ChNFs through a multifaceted mechanism. Adsorbed nanofibers confer electro-steric stabilization by extension into the aqueous phase. The strong ChNF network can physically entrap larger particles, greatly enhancing the long-term stability of ChNF-graphite suspensions. The ChNF-graphite dispersion exhibits rheological behavior suited for forming uniform electrode coatings. Electrodes prepared with 4% ChNFs deliver specific capacities of 370 mA h g^-1 and enhanced capacity retention over 100 cycles compared to PVDF-based counterparts. Electron microscopy, X-ray photoelectron spectroscopy, and online electrochemical mass spectrometry analyses reveal that the nature of the binder dictates the solid electrolyte interphase (SEI) characteristics. The ChNF produces a more robust and stable SEI that suppresses electrolyte reduction, directly contributing to the enhanced electrochemical performance.

Despite the relevance and abundance of studies on ion exchange processes, the current understanding of actual ionic interactions with charged moieties on the stationary phase is wanting in specificity. The Gibbs–Donnan and Donnan–Manning theories accurately describe membrane separation processes and ion selectivities but are incapable of describing the distinction between chemical ion association and condensation and physical electrostatic ion capture and retention. This is particularly relevant for pH-dependent processes, including membrane regeneration, when the chemical association of protons significantly alters the surface potential. In this study, we demonstrate how conductometry can provide both qualitative and quantitative information on the ion association and protonation behavior of phosphorylated cellulose pulp. Combined with an expanded model capable of distinguishing between associated and retained ions, we can simulate the conductometric data with reasonable agreement and, on that basis, predict the ion association behavior of the phosphorylated cellulose fibers in a ternary system of protons, Na+, and Ca2+ ions.

Achieving scalable fabrication with precise control of chiroptical properties in chiral plasmonic materials remains challenging. We present a new family of engineered chiroptical composites comprising linearly assembled gold nanoparticle arrays integrated with cholesteric self‐assembled cellulose nanocrystals (CNCs). Aqueous CNC suspensions are cast onto pre‐assembled achiral plasmonic nanoparticle arrays via evaporation‐induced transfer imprinting lithography, yielding centimeter‐scale hybrid films with custom‐tailored chiroptical responses. During drying, CNCs co‐assemble with the gold nanoparticles at the interface, preserving the array's linear arrangement and keeping it isolated from the overlying cholesteric CNC layers. This configuration combines the linear dichroism of the plasmonic array with the linear birefringence of the CNC matrix, producing strong and tunable plasmonic circular dichroism at the surface lattice resonance, reaching 1217 ± 51 mdeg with a dissymmetry factor of –0.19 ± 0.02. Our approach provides a sustainable platform for engineering multifunctional chiral plasmonic materials with potential applications in optical sensing, photonic devices, and chiral biointerfaces.