This research aimed to investigate the influence of the co-condensation of the three different organofunctional trialkoxysilane precursors with two different crosslinkers, i.e. tetraethoxysilane or organocyclotetrasiloxane on the performance and the washing fastness of this multicomponent multifunctional sol-gel coating on cellulose fibres. To this aim, a three-component equimolar sol mixture (MC), which included 1H,1H,2H,2H-perfluorooctyltriethoxysilane (SiF), 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (SiQ) and P,P-diphenyl-N-(3-(trimethoxysilyl)propyl) phosphinic amide (SiP) in combination with two different concentrations of TEOS (T and 3T) or organocyclotetrasiloxane 2,4,6,8-tetrakis(2-(diethoxy(methyl)silyl)ethyl)-2,4,6,8-tetramethyl–cyclotetrasiloxane (T4) as crosslinkers, was applied to the cotton fibres by a pad-dry-cure process. The functional properties of the coated samples before and after repeated washing were investigated by the water θ (W) and n-hexadecane θ (C16) static contact angle as well as water sliding (roll-off) (α) angle measurements. The inclusion of both TEOS and T4 into the MC sol increased the hydrophobic affect and simultaneously decreased the oleophobic effect of the MC coating. These phenomena were more pronounced for higher concentration of TEOS and T4 crosslinker. The inclusion of T4 into the MC sol improved the coating washing fastness to a significantly higher extent than the inclusion of TEOS, with respect to the applied concentrations.

Thickness Insensitive Spectrally Selective (TISS) paint coatings based on black pigment (PK 3060, Ferro Company) dispersed in a fluoropolymeric resin binder (Lumiflon, Asahi Company, Japan) have recently been made without added aluminium flakes and their properties have been reported for the first time. In this study we investigated in more detail the effect of trisilanol isobutyl (IB7 T7(OH)3) polyhedral oligomeric silsesquioxane (trisilanol POSS) on the surface modification of PK 3060 pigment. Infrared spectral analysis of the surface modified pigment particles provided firm evidence for the formation of a POSS layer on the surface of the pigment particles, substantiated by the corresponding TEM and Energy Dispersive X-ray Spectroscopy (EDXS) measurements of functionalized and as-received pigments. SEM micrographs of the diluted dispersions in fluoropolymeric resin binder revealed uniform distribution of pigment particles with an average size of ∼300 nm and the beneficial effect of the pigment functionalization was assessed from the measured spectral selectivity of coatings of various thicknesses.

Surfaces exhibiting antimicrobial activity were prepared for potential medical application. A polycationic lipopeptide polymyxin B was selected as the bioactive agent for covalent immobilization onto the surface. First, by using sol–gel technology the inert glass substrate was functionalized by a silane coating with epoxide rings to which the peptide was coupled by means of a catalyst. Preparation of the coating and presence of the peptide on the surface were followed by FTIR, XPS and AFM analyses. The obtained material showed antimicrobial effect indicating that in spite of immobilization the peptide has retained its bioactivity. The coated surface was able to reduce bacterial cell counts of the Gram-negative bacterium Escherichia coli by more than five orders of magnitude in 24 h of incubation. It can be concluded that bioactive coatings with covalently bound polycationic peptides have potential for application on medical devices where leakage into the surrounding is not allowed in order to prevent bacterial growth and biofilm formation.

The ionic liquid (PYR14TFSI) has proved to be the key material to make a Li-ion conducting element of a complete electrochromic device, when interposed between transparent film electrodes like WO3 and Li-charged V2O5. The key features of this ionic liquid and its mixtures with LiTFSI are the excellent transparency in the visible and NIR optical regions, the good ionic conductivity and the electrochemical compatibility with inorganic Li-intercalation oxide thin film electrodes used in electrochromic devices. The higher optical contrast found during WO3 colouration with PYR14TFSI-LiTFSI, compared to that in a conventional non-aqueous electrolyte like PC-LiTFSI, was attributed to the larger inertness of the former one (no decomposition reaction at the lowest electrode potential). This highly conductive ionic liquid has been incorporated into a polymer matrix (P(EO)10LiTFSI), in order to obtain a transparent solid electrolyte with high Li ion conductivity and good mechanical stability. Finally this solid PYR14TFSI-P(EO)10LiTFSI transparent ion conductor was interposed between the same electrodes as above in order to yield a fully solid-state, Li-ion electrochromic device. This new solid electrolyte was able to transfer reversibly a Li ionic charge between 5mCcm−2 and 10mCcm−2 from the lithium storage electrode LixV2O5 to the WO3 electrochromic electrode in less than 100s at room T, darkening the device from an initial 80% to a final 30% transmittance (at 650nm). Such a device has been tested first under various constant current conditions, and later under potentiostatic control using ±2V steps. The latter method allows not only for a faster response of the electrochromic system, but provides also an easier life stability test of the device, which withstood 2000 cycles with little changes in its optical contrast.

An electrochemical and in-situ Raman spectroelectrochemical study of 1-methyl-3-propylimidazolium iodide ionic liquid electrolyte (MPIm+Ix-) in the absence (x=1) and presence (x=3) of iodine is presented. Cyclic voltammetric measurements in combination with a platinum disk microelectrode revealed a remarkable difference before and after addition of iodine to the ionic liquid, implying the electrochemical formation of polyiodide ions (I5-) at potentials more positive than +0.6V in the presence of an equimolar amount of iodine. To verify this presumption, we performed in-situ Raman spectroelectrochemical measurements of MPIm+I− and MPIm+I−+I2 ionic liquids in a laboratory-made spectroelectrochemical cell, while stepwise changing the potential of the working platinum disk electrode. The results obtained were in good accordance with the above-mentioned postulate about the presence of polyiodide species (I5-), and can be conveniently employed in further investigations to elucidate of the Grotthus mechanism, associated with increasing conductivity as a result of the formation of polyiodides.

Novel proton-conducting electrolytes were prepared from the sol–gel precursor 1-[3-(trimethoxy-λ4-silyl)propyl]imidazole with the addition of either trifluoroacetic or acetic acid. The presence of trimethoxysilyl groups enabled the solvolysis and condensation reactions of silsesquioxane species. IR spectroscopy revealed that more cube-like species formed in the electrolyte prepared from trifluoroacetic acid, while cube- and ladder-like silsesquioxanes were present in the electrolyte with acetic acid. This assignation was independently confirmed by 29Si NMR analyses revealing the T3 signals of trisiloxane bonding. IR spectroscopy also pointed to the formation of hydrogen bonding in the latter electrolyte, since the frequencies of the observed bands at 1710, 1409, and 1272cm−1 approached those of acetic acid. In contrast, the IR bands at 1662, 1204, and 1130cm−1 confirmed the existence of trifluoroacetate anions in the case when the electrolyte was prepared from trifluoroacetic acid. The presence of free trifluoroacetate anions contributed to the moderately higher specific conductivity of this electrolyte (4.6×10−5S/cm) compared to that of acetic acid (1.6×10−5S/cm). The specific conductivity of the electrolytes could be further increased by the addition of a lithium salt. All electrolytes were employed in electrochromic devices with optically active WO3 and various inorganic counter-electrodes (CeVO4, V2O5, Ti/V-oxide). Photopic transmittance changes from 30% to 40% were achieved.

Polyiodides (Ix−, x=3 and 5) and 2I−…I2 adducts were established from the Raman spectra study of 1-methyl-3-propylimidazolium iodide (MPIm+Ix−; 1≤x≤5) ionic liquids containing various amounts of iodine (0mol≤I2≤2mol). The existence of I3− and 2I−…I2 was established for 1≤x≤2.5, symmetric I3− ions for x=3, while linear and discrete I5− was substantiated for 3≤x≤5. The presence of polyiodide species in MPIm+Ix− (1≤x≤5) was correlated with an enhanced ionic conductivity, attributed to the established relay-type Grotthus mechanism. Two-step conductivity increase was also reflected in decrease of the hydrogen bond interactions between the CH ring groups and polyiodides. While in the concentration range 1≤x≤3 (triiodides and tetraiodides) IR bands changed only slightly in intensity, in the concentration range x>3 the CH stretching bands (3040–3170cm−1) split and the new band at 1585cm−1 appeared in the IR spectra beside the already existing Im+ ring stretching mode at 1566cm−1.

Solid-state C-13 NMR and FTIR spectroscopy were applied to establish the chemical features of bulk mucous macroaggregates of phytoplanktonic origin at two different depths, surface and bottom, in the Gulf of Trieste (northern Adriatic Sea) in June 2000. The bottom sample was poor in organic matter (5% C-org, 0.5% N-tot)compared to the surface sample (17.2% C-org, 1.2% N-tot) and contained mostly senescent and degraded cells. An increase in mineral particles (quartz and calcite) was also evident. This was due to the degradation of the organic fraction and the contribution of bottom sediment resuspension. The C-13-NMR-based estimate showed the approximate composition of sampled macroaggregates: 26% aliphatic C, 14% O/N alkyl structures, 39% carbohydrates, 15% aromatic and olefinic C and 6% ester and/or amide C. The solid-state C-13 NMR spectrum of the sedimented macroaggregate revealed the preservation of aliphatic (lipidic) material and a portion of the labile nitrogen-containing compounds.

Nanocrystalline TiO2 films with a high surface roughness were prepared by the sol–gel route from titanium (IV) iso-propoxide and brij 56 surfactant. XRD and TEM showed that the films consisted predominantly of anatase nanoparticles embedded in an amorphous phase. Addition of the surfactant significantly increased the intensity of the surface hydroxyl modes between 3600 and 3750cm−1 in IR spectra. Spectroelectrochemical measurements of the films in 0.1M LiOH electrolyte revealed optical modulation beyond 70%T. Slow-scan cyclovoltammetry showed that bleaching occurred in two steps, suggested to correspond to anatase and amorphous phase. The changes that occur during intercalation and deintercalation were followed by ex-situ IR transmission measurements in the regions of Ti–O, carbonate and surface hydroxyl bands.

A new sol-gel precursor, based on 1-methyl-3-[3-(trimethoxy-lambda(4)-silyl)propyl]imidazolium iodide (MTMSPI(+)I(-)), was synthesized and investigated as a potential novel quasi-solid-state ionic liquid redox electrolyte for dye-sensitized photoelectrochemical (DSPEC) cells of the Graetzel type. MTMSPI(+)I(-) was hydrolyzed with acidified water, and the reaction products of the sol-gel condensation reactions were assessed with the help of (29)Si NMR and infrared spectroscopic techniques. Results of time-dependent analyses showed the formation of a positively charged polyhedral cubelike silsesquioxane species, which still contained a small amount of silanol end groups that were removed after heating at 200 degrees C. After cooling, the material formed was a tough, yellowish, and transparent solid, consisting mainly of ladderlike polysilsesquioxane species. The specific conductivity (sigma) of the nonhydrolyzed MTMSPI(+)I(-) (no I(2)) was 0.23 mS/cm, while the activation energy (E(a)), determined from the Vogel-Tamman-Fulcher (VTF) relation, was 0.29 kJ/mol. After 56 days of aging the sigma value of the hydrolyzed MTMSPI(+)I(-) dropped to 0.11 mS/cm but the viscosity had already increased to 7500 Pa.s after 17 days, demonstrating that a quasi solid state was attained. Apparent diffusion coefficients (D(app)) of I(-) and I(3)(-) obtained from the voltammetric measurements were approximately 10(-7) cm(2)/s and decreased to approximately 10(-8) cm(2)/s after 15 days of sol aging. Time-dependent vibrational spectra, which served in assessing the hydrolysis and condensation reactions of MTMSPI(+)I(-), were measured with the help of the attenuated total reflectance (ATR) IR spectroscopic technique. The results revealed that, in the course of condensation of sols, the refractive index of the modes attributed to the polysilsesquioxane species exhibited strong dispersion, which led to a shift of the vibrational band position in the experimental ATR spectra. This effect accompanies the sol-to-gel transformations and has not yet been considered as a possible error in analysis of the ATR spectra of sols and gels. The calculation procedure for obtaining the corresponding transmission spectra is briefly outlined, and the results are applied in this work.

A new sol–gel precursor, based on 1-methyl-3-[3-(trimethoxy-λ4-silyl)propyl]imidazolium iodide (MTMSPI+I−), was synthesized and investigated as a potential novel quasi-solid-state ionic liquid redox electrolyte for dye-sensitized photoelectrochemical cells of the Graetzel type. MTMSPI+I− was hydrolyzed with acidified water and the reaction products of the sol–gel condensation reactions were assessed with the help of 29Si NMR and infrared spectroscopic techniques, which revealed that the aged MTMSPI+I− sols consisted of a positively charged polyhedral cube-like silsesquioxane and iodide/triiodide species. The addition of iodine increased the specific conductivity of the non-hydrolyzed and hydrolyzed MTMSPI+I−, which was attributed to the formation of triiodide ions and demonstrated from Raman spectra measurements. Steady-state voltammetric measurements at a Pt disc microelectrode, performed for the hydrolyzed MTMSPI+I− and MTMSPI+I− + I2 sols, revealed changes in the apparent diffusion coefficients (Dapp) during the course of transformation of the ionic liquid from a liquid to a quasi-solid-state.

We produced V2O5 thin films with sol–gel technique, using in the synthesis as a template agent, the so-called ICS-PPG. We studied the electrochromic behaviour of thin films with electrochemical techniques as slow scan cyclic voltammetry and cyclic voltammetry (SSCV, CV), impedance spectroscopy (EIS) and potentiostatic intermittent titration (PITT). Moreover, we measured transmittance spectra, optical bandgap of the material and, with the help of transmission electron microscopy (TEM), we found out informations about films structure. The addition of ICS-PPG produces more transparent samples in comparison with samples prepared without template agent. The ion storage capacity is only slightly increased and, with ageing, some deposits appear on the surface limiting the electrochemical performances.

Nanocrystalline TiO2/Brij and TiO2/Pluronic films were prepared with a view to their application in electrochromic and Grätzel cells and examination of their photocatalytic effect. The films were prepared from titanium (IV) isopropoxide with the addition of Brij 56 or Pluronic F127. Films were deposited by dip-coating, thermally treated at 500 ∘C and analysed by XRD, TEM and IR analysis. XRD and TEM analyses revealed the presence of anatase nanoparticles embedded in the amorphous phase. The presence of the latter was also confirmed by a broad high-frequency shoulder of the Ti-O stretching mode at 436 cm−1 that was found for films prepared with both kinds of surfactants. Addition of surfactants decreased the size of the particles and increased the surface roughness, and consequently in IR spectra the surface hydroxyl Ti-OH modes appear between 3800 and 3600 cm−1. IR measurements also revealed that TiO2 films with surfactants have a higher photocatalytic effect which was tested for stearic acid by following the integral intensity of C-H and C=O IR bands.

Silica materials embedding ZrO2 or HfO2 were prepared by copolymerisation of organically modified oxozirconium or oxohafnium clusters M4O2(OMc)(12) (M = Zr, Hf and OMc = methacrylate) with (methacryloxymethyl) triethoxysilane or (methacryloxypropyl)trimethoxysilane. Free radical copolymerisation of the oxoclusters bearing 12 methacrylate groups with the methacrylate-functionalized siloxanes allows stable anchoring of the clusters to the silica network formed by the hydrolysis and condensation of the alkoxy groups. This route represents a valuable strategy to yield a very homogeneous dispersion of the MO2 precursors inside the silica matrix. The composition and the microstructural features of the starting hybrid gels were studied by solid state C-13 and Si-29 NMR spectroscopy and FT IR transmission spectroscopy. Their evolution upon mild heating (up to 180 degrees C) was followed by FTIR Attenuated Total Reflectance spectroscopy (ATR), while their thermal behaviour was studied by thermogravimetric analysis (TGA). The covalent incorporation of the clusters into the silica hybrid matrix was studied at several temperatures. Through X-Ray Diffraction (XRD) and Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS) it is demonstrated that temperatures above 800 degrees C yield binary oxides MO2-SiO2 (M = Zr, Hf). Delayed crystallisation of HfO2 and tetragonal ZrO2 from 450 degrees C to at least 800 degrees C was detected, which is ascribed to the presence of a homogeneous dispersion of the guest oxide in the silica matrix.

The micro-Raman spectroscopic technique was used to record the resonance Raman spectra of a semisolid redox electrolyte encapsulated in a hybrid electrochromic (EC) cell having the composition WO3 (active EC film)/redox (I-3(-)/I-) electrolyte/Pt (counter electrode). The electrolyte was made from bis end-capped triethoxy silane chemically bonded via the urea groups to a long poly(propyleneglycol) (n = 68) chain precursor. The precursor was catalyzed with acetic or valeric acid while KI and I-2 served as a source of K+ ions and I-3(-)/I- redox pair. The hybrid EC cell was electrochemically cycled between + 2 V (bleached state) and -2 V (colored state) and in the course of cycling the resonance Raman spectra were recorded. The spectra were characterized by a strong symmetric stretching mode of I-3(-) ions at 111 cm(-1) and its intensity changes could serve as a probe to follow the reaction 3I(-) reversible arrow I-3(-) + 2(e)(-) in the EC cell. Variation in intensity of the background scattering with potential was also noted and ascribed to the effect of the reversible precipitation of KI submicrometer crystals on the Raman scattering. The coloring/bleaching changes and the speed and the stability of hybrid EC cells are also reported. (C) 2004 The Electrochemical Society.