A5053335011- Advanced Cellulose Research Studies
- Electrospun Nanofibers in Biomedical Applications
- Lignin and Wood Chemistry
- Catalysis for Biomass Conversion
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Pickering emulsions and particle stabilization
- Crystallography and molecular interactions
- Advanced Materials and Mechanics
- Biofuel production and bioconversion
- Diamond and Carbon-based Materials Research
- biodegradable polymer synthesis and properties
- Advanced Chemical Physics Studies
- Aerogels and thermal insulation
- Advanced Data Storage Technologies
- Polysaccharides and Plant Cell Walls
- Nanocomposite Films for Food Packaging
- Carbon Nanotubes in Composites
- Fullerene Chemistry and Applications
- Ionic liquids properties and applications
- Advanced biosensing and bioanalysis techniques
- Liquid Crystal Research Advancements
- Wood Treatment and Properties
- Enzyme-mediated dye degradation
- Dyeing and Modifying Textile Fibers
University of Helsinki
2013-2024
VTT Technical Research Centre of Finland
2023-2024
Tieto (Finland)
2023-2024
Aalto University
2024
The University of Melbourne
2021
Justus-Liebig-Universität Gießen
2013-2020
National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”
2013-2017
Chevron (United States)
2009
Selective surface modification of biobased fibers affords effective individualization and functionalization into nanomaterials, as exemplified by the TEMPO-mediated oxidation. However, such a route leads to changes native chemistry, affecting interparticle interactions limiting development potential supermaterials. Here we introduce methodology extract elementary cellulose fibrils treatment biomass with N-succinylimidazole, achieving regioselective C6-OH, which can be reverted using mild...
Abstract Herein, we demonstrate the activation of commercial chemical cellulose pulps towards modification by a pre-treatment step with tetrabutylphosphonium acetate ([P 4444 ][OAc]). A heterogeneous (non-dissolving) was applied allowing for significant reduction in crystallinity, without concomitant formation thermodynamically stable II. An increase reactivity demonstrated using two model reactions; (1) acetylation (organic swelling conditions), where high degrees substitution (DS) were...
Abstract The limited access to fast and facile general analytical methods for cellulosic and/or biocomposite materials currently stands as one of the main barriers progress these disciplines. To that end, a diverse set narrow techniques are typically employed often time-consuming, costly, not necessarily available on daily basis practitioners. Herein, we rigorously demonstrate quantitative NMR spectroscopic method structural determination crystalline cellulose samples. Our relies use readily...
A new regioselective route is introduced for surface modification of biological colloids in the presence water. Taking case cellulose nanofibers (CNFs), we demonstrate a site-specific (93% selective) reaction between primary hydroxyl groups (C6-OH) and acyl imidazoles. CNFs bearing C6-acetyl C6-isobutyryl groups, with degree substitution up to 1 mmol g-1 are obtained upon esterification, affording adjustable energy. The morphological structural features remain largely unaffected, but...
Oxadiamondoids representing a new class of carbon nanoparticles were prepared from the respective diamondoid ketones via an effective two-step procedure involving addition methyl magnesium iodide and oxidation with trifluoroperacetic acid in trifluoroacetic acid. The reactivities oxacages are determined by position dopant good agreement computational predictions.
Gas-phase acylation is an attractive and sustainable method for modifying the surface properties of cellulosics. However, little known concerning regioselectivity chemistry, i.e., which cellulose hydroxyls are preferentially acylated if can be restricted to surface, preserving crystallinities/morphologies. Consequently, we reexplore simple gas-phase acetylation modern-day cellulosic building blocks - nanocrystals, pulps, dry-jet wet spun (regenerated cellulose) fibres a nanocellulose-based...
The nature of marine biomass is very complex for a material scientist due to the large seasonal variation in chemical composition that makes it difficult prepare standardized products. A systematic investigation interaction microwave irradiation with seaweed from Norway and Caribbean region was performed, covering broad temperature range (130 → 170 °C) without addition ℽ-valerolactone ratios 1:4 1:2. temperatures above 150 °C led closure mass balances up 90 % includes polysaccharides,...
Cellulose-based materials are gaining increasing attention in the packaging industry as sustainable material alternatives. Lignocellulosic polymers with high quantities of surface hydroxyls inherently hydrophilic and hygroscopic, making them moisture-sensitive, which has been retarding utilization cellulosic applications requiring moisture resistance. Herein, we produced lightweight all-cellulose fiber foam films improved water tolerance. The foams were modified willow bark extract (WBE)...
Herein, we demonstrate an effective approach toward functionalization of cellulose nanocrystal (CNC) reducing ends by means a Knoevenagel condensation reaction with reactive β-diketone (acetylacetone). The end-wise modification was elucidated advanced NMR analysis, which facilitated dissolving the CNCs in ionic liquid electrolyte and concomitant assignment model compound derived from d-cellobiose. diffusion-edited 1H experiment afforded simple method to identify assigned resonances...
We investigated the valence electronic structure of diamondoid particles in gas phase, utilizing photoelectron spectroscopy. The samples were singly or doubly covalently bonded dimers trimers lower diamondoids. Both bond type and combination bonding partners are shown to affect overall structure. For particles, we observe a small impact on structure, whereas for connecting determines highest occupied orbitals. In superposition partner orbitals experimental findings supported by density...
Nanometer-sized doubly bonded diamondoid dimers and trimers, which may be viewed as models of diamond with surface sp(2)-defects, were prepared from corresponding ketones via a McMurry coupling characterized by spectroscopic crystallographic methods. The neutral hydrocarbons their radical cations studied utilizing density functional theory (DFT) ab initio (MP2) methods, reproduce the experimental geometries ionization potentials well. van der Waals complexes oligomers that are for...
When cellulose nanocrystals (CNCs) are isolated from microfibrils, the parallel arrangement of chains in crystalline domains is retained so that all reducing end-groups (REGs) point to one crystallite end. This permits selective chemical modification end CNCs. In this study, two reaction pathways compared selectively attach atom-transfer radical polymerization (ATRP) initiators REGs CNCs, using reductive amination. further enabled site-specific grafting anionic polyelectrolyte poly(sodium...
We investigate the interplay between cellulose crystallization and aggregation with interfibrillar interactions, shear forces, local changes in medium's acidity. The latter is affected by CO
The European Commissions single-use plastics directive has put major restrictions on the use of chemically modified cellulosics for different material applications, e.g., as films, fibres, foams and other shaped objects. In addition, wet strength barrier properties some these materials are lacking, in comparison to petrochemical-based plastics. current study we demonstrate that it is possible carry out surface selective acetylation kraft fibre paper nano-paper create maintain...
Abstract Regioselective modifications of cellulose using activated derivatives such as 6‐halo‐6‐deoxycelluloses provide a convenient approach for developing sustainable products with properties tailored to specific applications. However, maintaining precise regiochemical control substituent distribution in is challenging due their insolubility most common solvents and the resulting difficulties structure elucidation by modern instrumental analytical techniques. Herein, an accessible...
The reaction of reducing end groups in cellulose nanocrystals with dodecylamine was examined. Using a direct-dissolution solution-state NMR protocol, the regioselective formation glucosylamines shown. This provides an elegant approach to sustainably functionalize these bio-based nanomaterials, that may not require further reduction more stable secondary amines.
We present resonance Raman measurements of crystalline trishomocubane and diamantane dimers containing a C=C double bond. spectra were recorded with excitation energies between 2.33 eV 5.42 eV. The strongest enhancement is observed for the stretch vibration bending mode involving two carbon atoms bond, corresponding to B2g wagging ethylene. This associated localization π-HOMO LUMO elongation bond length pyramidalization sp(2)-hybridized at optical excitation. are significantly lower than...
We analyzed the vibrational and electronic properties of diamondoid oligomers via resonance Raman spectroscopy. The compounds consist lower diamondoids such as adamantane or diamantane that are interconnected with double bonds. Therefore, all have ethylene-like centers strongly influencing character optical transitions. bond localizes HOMO (highest occupied moluecular orbital) in between accompanied by a significant decrease transition energies. Comparing spectra to pristine diamondoids, we...
Regenerated cellulose products are attracting increasing attention as sustainable alternatives to petroleum-based materials, especially in the packaging and textile industries. Ionic liquids (ILs) often described "green" options for dissolution due low toxicity volatility. Most studies on regeneration of utilize high-purity dissolving pulps, which known be more "reactive" than kraft pulps. Therefore, we investigated influence hemicellulose content solubility ability softwood pulps well grade...
Chlorophyll derivatives were functionalized with a trifluoroamide (TFA) group to obtain colorimetric ion sensors. Prior this, NO2BF4*pyridine based, chlorin nitration method was developed. The base strength dependent sensing of AcO−, F− and CN− ions detected in aqueous media, which enhanced nonprotic solvents by an integration the ditopic chelation capable amine crown-6 moiety.
The electronic properties of sp2/sp3 diamondoids in the crystalline state and gas phase are presented. Apparent differences experimentally observed by resonance Raman spectroscopy crystalline/gas absorption measurements were investigated density functional theory computations. Due to a reorganization molecular orbitals phase, HOMO (highest occupied orbital) LUMO (lowest unoccupied energy gaps lowered significantly 0.5 eV–1 eV. π → π* transition is responsible for large both phases. It...
A new regioselective route is introduced for surface modification of biological colloids in the presence water. Taking case cellulose nanofibers (CNFs), we demonstrate a site-specific (93% selective) reaction between primary hydroxyl groups (C6-OH) and acyl imidazoles. CNFs bearing C6-acetyl C6- iso -butyl groups, with degree substitution up to 1 mmol·g –1 were yielded upon esterification, affording adjustable energy. The morphological structural features remained largely unaffected, but...
Aim. To study the effect of electronic (α- and β-hyperconjugations) steric (noncovalent interactions) factors on structures olefinic radical cations.Results discussion. The intramolecular dispersion interactions crowded alkenes in neutral ionized forms has been studied at density functional theory (DFT) level with without corrections included, as well MP2 medium size basis sets. results obtained are compared to available experimental data. An excellent agreement found between...