Pia Damlin

Switchable Ionic liquids (SILs) based on glycerol and acid gases

New types of switchable ionic liquids (SILs), containing 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU), glycerol and an acid gas (CO2, SO2), were synthesized and characterized in this study. [DBU][Carbonate] or [sulfonate] were easily synthesized from a non-ionic mixture of molecular organic polyol and amidine base upon bubbling of an acid gas (CO2, SO2). Moreover, they were switched back to the original molecular solvents by flushing out the acid gas (CO2, SO2) by heating and/or bubbling an inert gas such as N2 through it. The structures of the SILs were confirmed by NMR and FTIR. The change from low polarity (molecular solvent) to high polarity (Switchable Ionic Liquid, SIL) was also indicated by the changes in properties, such as viscosity and miscibility with different organic solvents. The decomposition temperatures of the SILs were determined by means of Thermo Gravimetric Analysis (TGA) and gave values in the range of 50 °C and 120 °C for DBU-glycerol-CO2 (SIL1) and DBU-glycerol-SO2 (SIL2), respectively. Due to the reasonable decomposition temperatures, these novel SILs can be employed in multiple applications.

Treating birch wood with a switchable 1,8-diazabicyclo-[5.4.0]-undec-7-ene-glycerol carbonate ionic liquid

Abstract The suitability of a new switchable ionic liquid (SIL) has been investigated as a solvent for fractionation of lignocellulosic materials. SIL was prepared from inexpensive chemicals, e.g., glycerol, CO2, and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU). Fresh Nordic birch wood (B. pendula) was treated with the SIL for a time period of 1–5 days at 100°C and under atmospheric pressure. Upon SIL treatment, at best, 57% of the hemicelluloses were dissolved and 50% of lignins were dissolved from the native birch. The slightly fibrillated SIL treated chips contained about 55% cellulose. Up to 76% of the recovered species removed from the spent SIL liquor was originating from hemicelluloses, mainly from xylan. The spent SILs were reused for fresh wood dissolution in four consecutive cycles and each time the wood dissolution efficiency was similar. SILs could offer affordable (easy-to-synthesize) solvent systems for partial elimination of hemicelluloses and lignin from wood. SILs can also be prepared in-situ and on-site.

Electrochemical synthesis of poly(paraphenylene vinylene) films

Abstract Poly( para phenylene vinylene) was prepared by electrochemical reduction of α , α , α ′, α ′-tetrabromo- p -xylene. The effect of different parameters on the quality of the formed polymer film was studied: monomer material, supporting electrolyte, electrode material, polymerization potential and the preparation procedure. The films polymerized in different electrolyte solutions were studied by sweep electron microscopy (SEM), cyclic voltammetry (CV) and with in situ conductometry measurements. Energy dispersive X-ray analysis (EDXA), dispersive Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy techniques were used to study the structure of the formed polymer films.

An electrochemical quartz crystal microbalance study on growth of and ion transport in electrochemically polymerized poly(paraphenylene vinylene)

Abstract The electrochemical quartz crystal microbalance technique has been used to study in situ the mass changes that take place during electrochemical growth and redox cycling of the conducting polymer poly( p -phenylenevinylene) (PPV). The polymer material has been grown onto platinum in dimethylformamide using tetraethylammonium tosylate (TOS) or tetraethylammonium tetrafluoroborate (BF 4 ) as electrolyte salts. The mass change during polymerization of PPV films under various monomer concentrations was studied and also the effect of water added to the polymerization solution. The results show that the polymerization reaction was enhanced when 1. water was added to the polymerization solution, 2. the concentration of monomer material was increased, and 3. when the polymerization was done in presence of a medium-sized anion. When the PPV films were grown with a medium-sized anion (TOS − ), cations were inserted and removed during the redox process in order to compensate for the change in charge of the PPV film. The films prepared in presence of a small anion (BF − 4 ) showed anion motion during the redox cycling.

Electrosynthesis and characterisation of poly(paraphenylene vinylene C60) films

The electrochemical reductive polymerization of a co-polymer of phenylene vinylene units and C 60 was studied. The fullerene is introduced into the polymer synthesis as a film on the electrode substrate. During reduction the film is dissolved and the reduced fullerene species interact with the PPV precursor in solution and as a result a film is formed on the substrate. The coupling reaction between the reduced species should lead to a material where the fullerene units are incorporated into the main polymer chain. The films are characterised by cyclic voltammetry and by FTIR and Raman spectroscopy.

Ionic Liquid-Aided Carboxymethylation of Kraft Pulp

Different ionic liquids containing the cation such as 1-N-butyl-3-methylimida-zolium (Bmim+) are able to efficiently dissolve cellulose. The ability of ionic liquids to truly dissolve cellulose is significant when cellulose derivatization is attempted. A series of experiments on etherification (carboxymethylation) of cellulose was performed, using both the conventional suspension approach (slurry) with 2-propanol as the principal reaction media and a totally homogenous reaction approach utilizing ionic liquids as a reaction media capable of dissolving cellulose. It was observed that a pre-treatment with the ionic liquid 1-N-butyl-3-methylimidazolium iodide ([Bmim][I]) seems to promote substitution in line with the conventional, heterogeneous suspension process. Under carefully chosen reaction conditions, a higher degree of substitution was obtained when wetting the cellulose with [Bmim][I] prior to classical derivatization than without this pre-treatment. It was also observed that the substitution pattern was changing upon use of the ionic liquid [Bmim][I]. Upon a totally homogenous etherification, it was found that the ionic liquid 1-N-butyl-3-methylimidazolium acetate ([Bmim][oAc]) gave the highest degree of substitution. The product obtained was water-soluble and had a DS (degree of substitution) of 0.59. The substitution pattern of the products obtained from the homogenous reactions follow the same substitution pattern as the products obtained from the conventional suspension process. This indicates that the properties of the products are in line with products prepared via the conventional reaction route.

In situ UV-Vis ESR studies on electrochemically synthesized poly(p-phenylene vinylene)

In this work PPV films were prepared by electrochemical reduction of α,α,α,α-tetrabromo-p-xylene in dimethylformamide and tetraethylammonium tetrafluoroborate. To get more information about the mechanism behind electrochemical polymerization of PPV and its doping reaction, in situ ESR- UV-VIS measurements were made on the electrochemically synthesized conducting polymer PPV.

Characterization of electrochemically synthesized PPV by in situ FTIR-ATR and resonant Raman spectroscopy

In this work the electrochemical synthesis and the redox reactions (both n- and p-doping) of poly(paraphenylene vinylene) (PPV) have been studied in situ by Fourier Transform Infrared (FTIR) spectroscopy using the attenuated total reflection (ATR) method and by resonant Raman spectroscopy. During electrochemical polymerization a growth of bands assigned to PPV was observed both in FTIR and Raman spectra. The charging-discharging reaction of the PPV films showed reversible spectral changes.

A Chemical Engineering Approach to Cellulose Substitution Kinetics

A general kinetic model for the substitution of cellulose was developed. The model assesses the differences in the reactivity of the cellulose hydroxyl groups and a decrease in the reactivity as the substitution proceeds. The model predicts the detailed distribution of the different mono (2, 3, 6)-, di (23, 26, 36) – and trisubstituted (236) units as a function of the reaction time. The classical Spurlin distribution is obtained as a special case of the general model. Numerical strategies were developed for the solution and computer simulation of the model. Simulation results were shown to be valid for various reactivity ratios of the hydroxyl groups. The modelling concept was verified with experimental data obtained for carboxymethylation of cellulose in a slurry reactor. The detailed data, which revealed the non-uniform reactivities of the different hydroxyl groups and the decline of the substitution rate with time, were successfully described by the mathematical model.

Electrosynthesis of conducting polymer films containing C60

An electrochemical route for production of polymeric fullerenes is presented. The aim has been to obtain materials where the fullerene units are incorporated into the main polymer chain. The conducting polymers Poly(paraphenylene) PPP and Poly(paraphenylene vinylene) PPV, are synthesized by electroreductive polymerization on top of a drop cast C 60 fullerene film. The films are characterized by cyclic voltammetry and by Raman spectroscopy.