Istvan Furo

KTH Royal Institute of Technology | KTH · Department of Chemistry

Invited for this month′s cover is the groups of Prof. Minna Hakkarainen, Prof. István Furó and Assoc. Prof. Per‐Olof Syrén at KTH Royal Institute of Technology. The image shows how microwave irradiation is an efficient pre‐treatment method of polyethylene terephthalate (PET) for subsequent biocatalytic depolymerization. The Research Article itself...

Recycling plastics is the key to reaching a sustainable materials economy. Biocatalytic degradation of plastics shows great promise by allowing selective depolymerization of man-made materials into constituent building blocks under mild aqueous conditions. However, insoluble plastics have polymer chains that can reside in different conformations an...

Alternative electrolyte systems such as hybrid electrolytes are much sought after to overcome safety issues related to liquid electrolytes in lithium ion batteries (LIBs). Hybrid solid-liquid electrolytes (HEs) like the...

The energy density and lifetime of lithium-ion cells for automotive applications have both substantially improved in recent years. This enables electric vehicles in both the consumer and commercial sectors that have greater range, better reliability, and longer service lives [1]. These factors all contribute to the widespread adoption of electric v...

A key degradation mechanism in lithium-ion batteries (LIBs) is the irreversible loss of cyclable lithium during cycling. At the graphite negative electrode, this loss occurs through the deposition of lithium-containing compounds in the solid-electrolyte interphase (SEI) and through plating of metallic lithium, resulting in so-called dead lithium. T...

While strong water association with cellulose in plant cell walls and man-made materials is well-established, its molecular scale aspects are not fully understood. The thermodynamic consequences of having water molecules located at the microfibril-microfibril interfaces in cellulose fibril aggregates are therefore analyzed by molecular dynamics sim...

Exploration of efficient water oxidation catalysts (WOCs) is the primary challenge in conversion of renewable energy into fuels. Here we report a molecularly well-defined heterogeneous WOC with Aza-fused, π-conjugated, microporous polymer (Aza-CMP) coordinated single cobalt sites (Aza-CMP-Co). The single cobalt sites in Aza-CMP-Co exhibited superio...

Due to the steric effects imposed by bulky polymers, the formation of catalytically competent enzyme and substrate conformations is critical in the biodegradation of plastics. In poly(ethylene terephthalate) (PET), the backbone adopts different conformations, gauche and trans, coexisting to different extents in amorphous and crystalline regions. Ho...

Atomistic molecular dynamics simulation is an important complement to experimental techniques for investigating properties of hydrated carbohydrate polymers at the molecular scale. A critical problem is to determine whether or not a simulation has converged to thermal equilibrium before data collection can begin. In this work, simulations of xylan...

In the cellulose scientific community, hydrogen bonding is often used as the explanation for a large variety of phenomena and properties related to cellulose and cellulose based materials. Yet, hydrogen bonding is just one of several molecular interactions and furthermore is both relatively weak and sensitive to the environment. In this review we p...

We investigate hard carbon fibers at different states of charge by a combination of 7Li-NMR and 2D-XRD. In particular, we record the quadrupole-split 7Li-NMR spectra and 7Li longitudinal relaxation over...

Ion specific effects are ubiquitous in solutions and govern a large number of colloidal phenomena. To date, a substantial and sustained effort has been directed at understanding the underlying molecular interactions. As a new approach, we address this issue by sensitive ¹H NMR methods that measure the electrophoretic mobility and the self-diffusion...

Dispersing graphene sheets in liquids, in particular water, could enhance the transport properties (like thermal conductivity) of the dispersion. Yet, such dispersions are difficult to achieve since graphene sheets are prone to aggregate and subsequently precipitate due to their strong van der Waals interactions. Conventional dispersion approaches,...

Electrophoretic NMR has the capacity to provide unique physico-chemical information but is limited by a variety of experimental artifacts, such as thermal convection and electrolytic products in the sample. Here we present some simple modifications to the experimental hardware and protocol that, in a significant number of cases, can much improve ex...

Quartz crystal microbalance (QCM) has been used to study how the interfacial layer of an ionic liquid dissolved in a polar oil at low weight percentages responds to changes in applied potential. The changes in surface composition at the QCM gold surface depend on both the magnitude and sign of the applied potential. The time resolved response indic...

Lithium-ion-free tris(2,2’-bipyridine) Co(II/III)-mediated electrolytes have previously been proposed for long-term stable dye-sensitized solar cells (DSSCs). Such redox system also offers an impressive DSSC performance improvement under light soaking exposure, manifested by an increase in photocurrent and fill factor without the expense of decreas...

The rich pool of protein conformations combined with the dimensions and properties of carbon nanotubes create new possibilities in functional materials and nanomedicine. Here, the intrinsically disordered protein α-synuclein is explored as a dispersant of single-walled carbon nanotubes (SWNTs) in water. We use a range of spectroscopic methods to qu...

Surfactants have been widely employed to debundle, disperse and stabilize carbon nanotubes in aqueous solvents. Yet, a thorough understanding of the dispersing mechanisms at molecular level is still warranted. Herein, we investigated the influence of the molecular structure of gemini surfactants on the dispersibility of multiwalled carbon nanotubes...

The properties of porous material are largely dependent on the size, shape, and connectivity of the pores. Here we present a method based on confocal Raman spectroscopy to quantify porosity using a cryoporometric approach. We show that the phase transition of water imbibed in porous silica can be accurately determined using two different, but compl...

It is demonstrated that a phosphonium orthoborate ionic liquid may serve as a wear reducing additive in biodegradable oils at steel-steel surfaces in the boundary lubrication regime. Tribological tests were performed in a ball-on-three plate configuration. A set of surface characterization techniques—SEM/EDS, FIB and white light interferometry were...

Propofol is an amphiphilic non-surfactant that strongly influences the function of cell membranes, yet data regarding interfacial properties of propofol remains scarce. Here we consider propofol adsorption at the air/water interface as elucidated by means of vibrational sum frequency spectroscopy (VSFS), neutron reflectometry (NR), and surface tens...

When using amphiphilic polymers to exfoliate and disperse carbon nanotubes in water the balance between the hydrophobic and hydrophilic moieties is critical and nontrivial. Here, we investigate the mode of surface attachment of a triblock copolymer, Pluronics F127, composed by a central hydrophobic polypropylene oxide block flanked by hydrophilic p...

Debundling and dispersing single-walled carbon nanotubes (SWNTs) is essential for applications but the process is not well understood. In this work, aqueous SWNT dispersions were produced by sonicating pristine SWNT powder in the presence of an amphiphilic triblock copolymer (Pluronic F127) as dispersant. Upon centrifugation, one obtains a supernat...

Size-exclusion quantification NMR spectroscopy (SEQ-NMR) is introduced for measuring equilibrium distribution coeffi-cients, Keq, in porous media. The porous medium is equilibrated with a polydisperse polymer solution. The original bulk polymer solution and the polymer solution after equilibration but in the absence of the porous medium are analyze...

The integration of carbon nanotubes (CNTs) into a polymer matrix strongly affects the rheological behavior that in turn may hamper the overall performance of the resulting composite. Research in this topic has focused on bulk rheological properties, while here we employ NMR diffusion experiments to explore the mobility (diffusivity) of epoxy molecu...

Macromolecular dynamics in biological systems, which play a crucial role for biomolecular function and activity at ambient temperature, depend strongly on hydration. Yet, a generally accepted quantitative model of hydration-dependent phenomena based on local relaxation and diffusive dynamics of both polymer and its hydration water is still missing....

By combining NMR (yielding 1H chemical shift, spin relaxation and self-diffusion data) and SAXS experiments, we investigate the complex temperature dependence of the molecular and aggregate states in aqueous solutions of the surfactant [CH3(CH2)17(OCH2CH2)20OH], abbreviated C18E20, and hexamethyldisiloxane HMDSO. The latter molecule serves as a mod...

The effects of γ radiation in air and water on a highly filled carbon-black-containing EPDM seal, used in transportation valves for old-fuel rods, were investigated. Samples were irradiated at a dose rate of 7 kGy h⁻¹ until total doses of 0.35, 1.4, 2.1 and 3.5 MGy were reached. The doses were chosen to correspond to 1, 4, 6 and 10 years of service...

The effects of air ageing at different temperatures between 110 and 170 °C on cable transit seals based on highly filled EPDM rubber used in nuclear power plants were studied. The changes of the macroscopic mechanical properties (Young's modulus, indentation modulus and strain-at-break) were in accordance with the Arrhenius equation with an activat...

Highly filled EPDM rubber used in cable transit seals in nuclear power plants were exposed to γ radiation at a high dose rate at 23 °C in media with different oxygen partial pressures (1–21.2 kPa). The motivation of this study was threefold: highly filled polymers are replacing halogen-containing polymers and these materials have rendered less atte...

The self-diffusion of neat water, dimethylsulfoxide (DMSO), octanol and the molecular components in a water-DMSO solution were measured by 1H and 2H NMR diffusion experiments for those fluids imbibed into Controlled Pore Glasses (CPG). Their highly interconnected structure is scaled by pore size and shows invariant pore topology independently of th...

The bulk self diffusion of the ethylammonium cation and the nitrate anion can both be described by respective single diffusion coefficients. Diffusion of the anion is 1.7 times higher than that of the cation. This indicates no tight association of the ions in the ionic liquid. For the ethylammonium cation confined between glass plates the effective...

The binding in methanol of K+ and Ba2+ cations to short polyethyleneoxide (PEO) chains with ca 4-25 monomeric units was studied via determining the effective charge of the polymer by a combination of electrophoretic NMR (eNMR) and diffusion NMR experiments. These cations were previously found to bind on similar strong manner to long PEO chains. In...

The organization of water molecules adsorbed onto cellulose and the supramolecular hydrated structure of microfibril aggregates represents, still today, one of the open and complex questions in the physical chemistry of natural polymers. Here, we investigate by (2)H MAS NMR the mobility of water molecules in carefully (2)H-exchanged, and thereafter...

Mechanical agitation is commonly used to fragment and disperse insoluble materials in liquids. However, here we show that when pristine single-walled carbon nanotubes pre-dispersed in water are subject to vortex-shaking for very short periods (typically 10-60 s, power density ∼ 0.002 W.mL⁻¹), re-aggregation counterintuitively occurs. The initial di...

In order to establish the potential correlation between the macroscopic ice adhesion and the molecular properties of the premolten layer (PML), the adhesion strength between ice and hydrophilic silica has been measured as a function of temperature. In addition, temperature-dependent molecular properties have been determined using techniques that ar...

Electrophoretic displacement of charged entities phase modulates the spectrum acquired in electrophoretic NMR experiments and this modulation can be presented via 2D FT transformation as 2D MOSY (MObility SpectroscopY) spectra. We compare in various mixed solutions the chemical selectivity provided by 2D MOSY spectra to that provided by 2D DOSY (Di...

Cellulose, one of the most abundant renewable resources, is insoluble in most common solvents but dissolves in aqueous alkali under a narrow range of conditions. To elucidate the solubilization mechanism, we performed electrophoretic NMR on cellobiose, a subunit of cellulose, showing that cellobiose acts as an acid with two dissociation steps at pH...

Complex formation in methanol between monodisperse polyethylene oxide (PEO) and a large set of cations was studied by measuring the effective charge acquired by the PEO upon complexation. Quantitative data were obtained at the low ionic strength of 2 mM (for some salts, also between 0.5 mM and 6 mM) by a combination of diffusion NMR and electrophor...

The interaction of water with cellulose stages many unresolved questions. Here ²H MAS NMR and IR spectra recorded under carefully selected conditions in ¹H[single bond]²H exchanged, and re-exchanged, cellulose samples are presented. It is shown here, by a quantitative and robust approach, that only two of the three available hydroxyl groups on the...

Wide-spread use of cellulose nanofibril (CNF) biocomposites and nanomaterials is limited by CNF moisture sensitivity due to surface hydration. We report on a versatile and scalable interface tailoring route for CNF to address this, based on technically important epoxide chemistry. Bulk impregnation of epoxide-amine containing liquids is used to sho...

Orders of magnitude decrease of 207 Pb and 199 Hg NMR longitudinal relaxation times T 1 upon magic-angle-spinning (MAS) are observed and systematically investigated in solid lead and mercury halides MeX2 (Me = Pb, Hg and X = Cl, Br, I). In lead( ii) halides, the most dramatic decrease of T 1 relative to that in a static sample is in PbI2, while i...

We investigate a way one can achieve good spectral resolution in 2H MAS NMR experiments. The goal is to be able to distinguish between and study sites in various deuterated materials with small chemical shift dispersion. We show that the 2H MAS NMR spectra recorded during a spin-relaxation experiment are amenable to spectral decomposition because o...

Among the alternative host materials for solid polymer electrolytes (SPEs), polycarbonates have recently shown promising functionality in all-solid-state lithium batteries from ambient to elevated temperatures. While the computational and experimental investigations of ion conduction in conventional polyethers have been extensive, the ion transport...

A method based on 1H high-resolution magic angle spinning NMR has been developed for measuring concentration accurately in heterogeneous materials like that of ligands in chromatography media. Ligand concentration is obtained by relating the peak integrals for a butyl ligand in the spectrum of a water-saturated chromatography medium to the integral...

The binding strength of dispersants to the surface of carbon nanotubes is of crucial importance for the efficiency of the dispersion process and for potential applications, yet data are scarce on this subject. Here we present the results of diffusion NMR experiments in dispersions of single-walled carbon nanotubes (SWNTs) prepared by either the pol...

A fundamental understanding of the mechanisms involved in the surfactant-assisted exfoliation and dispersion of carbon nanotubes (CNTs) in water calls for well-controlled experimental methodologies and reliable comparative metrics. We have assessed the ability of several ionic surfactants to disperse single and multi-walled carbon nanotubes, resort...

Supporting info item

Nonionic surfactants containing Poly(Ethylene Oxide) are chemically simple and bio-compatible and form core-shell micelles at a wide range of conditions. For those reasons, they and their aggregates have been widely investigated. Recently, irregularities that were observed in the low-temperature behavior of surfactants of the kind [CH3(CH2)nO(CH2CH...

A method for measuring the ligand concentration in heterogeneous materials like chromatography media is described. In this method, (13) C single pulse excitation magic angle spinning NMR experiment with broadband (1) H decoupling is used to determine the peak integrals for a butyl ligand in the spectrum of a dried chromatography medium. Within a ca...

Improved moisture stability is desired in cellulose biocomposites. In order to clarify nanostructural effects, a new approach is presented where water and polymer matrix mobilities are characterized separately. Nanocomposites from cellulose nanofibers (CNF) in xyloglucan (XG) biopolymer matrix are investigated at different hydration states. Films o...

Core-shell wood cellulose nanofibers (CNF) coated by an XG hemicellulose polymer are prepared and used to make biocomposites. CNF/XG biocomposites have interest as packaging materials and as hydrated CNF/XG plant cell wall analogues. Structure and properties are compared between Core-shell CNF/XG and more inhomogeneous CNF/XG. Experiments include X...

The results of diffusion and electrophoretic NMR (eNMR) measurements are reported for a series of tetramethylammonium (TMA) electrolytes (with sulphate, fluoride, acetate, chloride, bromide, nitrate, iodide and perchlorate as anions) in deuterated solvents such as water, dimethylsulphoxide (DMSO), acetonitrile, methanol and ethanol. In addition, si...

The performance of a new electrophoretic NMR (eNMR) method that uses a Carr-Purcell-Meiboom-Gill echo train with repeated electric field reversal is investigated. We show that this pulse sequence, with acronym CPMGER, yields strongly reduced artifacts from convective flow effects caused by the simultaneous presence of electroosmotic and thermal dri...

Noncovalent dispersion of carbon nanotubes is essential to most applications but still poorly understood at the molecular level. The interaction of the dispersing molecule with the nanotube, wrapping or nonwrapping, still awaits consensus. Herein, we have studied by H-1 NMR diffusometry some features of molecular dynamics in the system of carbon na...

The cellular structure of wood, highly anisotropic along its main growth directions is responsible for the observed anisotropy in its physical and mechanical properties that, in addition, depend in a complex manner on the moisture content. Here, we demonstrate that the 1H NMR spectra of wood from Norway spruce exhibit a strong and characteristic de...

Exchange of nuclear magnetization between spin pools, either by chemical exchange or by cross-relaxation or both, has a significant influence on the signal attenuation in stimulated-echo-type pulsed field gradient experiments. Hence, in such cases the obtained molecular self-diffusion coefficients can carry a large systematic error. We propose a mo...

We measured with high accuracy the effective charge of a uranium(VI)–AMP complex by electrophoretic NMR (eNMR). Using the same method, the degree of counterion association is also assessed which leads to a quantitative determination of the nominal charge which then provides the degree of ligand deprotonation in the complex. This demonstrates a new...

We demonstrate that chemical-shift-selective constant-time imaging (CTI) can be performed by simply inserting selective saturation into the original imaging pulse sequence. The performance of the proposed method is illustrated by (7)Li CTI imaging in a battery model that contains both Li metal electrodes and an electrolyte containing a dissolved Li...

Despite having been used for ages to protect wood against the influence of outdoor elements, the chemistry of vegetable oils within wood is poorly known. We propose a method based on solid-state magic-angle sample spinning NMR to in situ characterize oil oxidation as well as its immobilization. To eliminate signal coming from wood molecules but to...

The nature of the reentrant nematic phase has been actively investigated both experimentally and theoretically during the past few decades. Most studies concluded that, as concerning molecular dynamics, a reentrant nematic phase is essentially analogous to a conventional nematic one. Recent computer simulations [Mazza et al., Phys. Rev. Lett. 105,...

Poor mass transport in the electrolyte of Li ion batteries causes large performance losses in high-power applications such as vehicles, and the determination of transport properties under or near operating conditions is therefore important. We demonstrate that in situ (7)Li NMR imaging in a battery electrolyte can directly capture the concentration...

The binding of block copolymer Pluronic F-127 in aqueous dispersions of single- (SWCNT) and multiwalled (MWCNT) carbon nanotubes has been studied by pulsed-field-gradient (PFG) (1)H NMR spectroscopy. We show that a major fraction of polymers exist as a free species while a minor fraction is bound to the carbon nanotubes (CNT). The polymers exchange...

The overall aim of this study is to develop new wood modifications using vegetable oils to obtain improved durability of wood materials in an environmentally friendly way. Nuclear magnetic resonance (NMR) and Fourier-transform infrared (FT-IR) spectroscopies were used to study oxidation and possible chemical coupling reactions between polyunsaturat...

This study evaluated the capability of nuclear magnetic resonance (NMR) technology based on small portable magnets for in situ studies of the local moisture content in wood. Low-field and low-resolution [1H]NMR with a unilateral permanent magnet was used to monitor and map the moisture content of wood cladding materials of various types in a spatia...

The freezing-melting hysteresis of water in mesoporous silicas MCM-48, MCM-41 and SBA-16 has been studied by NMR cryoporometry. The hysteresis in MCM-48 was found to exhibit nearly parallel branches, matching type H1 hysteresis that had been observed earlier in controlled pore glass. The same type of hysteresis is observed in two of three different...

Despite the advantages offered by solid dispersions, the marketed products based on this technology are few. The most frequent concern is the stability of the amorphous drug. The state of the drug in solid dispersions is, in general, poorly characterized as the number of characterization techniques available to monitor nanometer-sized drug particle...

The freezing and melting temperature hysteresis of water in Vycor porous glass and controlled pore glass (CPG) with the nominal pore diameters 7.0 and 7.5 nm, respectively, has been explored by NMR cryoporometry and NMR relaxometry techniques. The freezing branch of the hysteresis in Vycor was found to be much steeper than the melting one, presumab...