Composition Of Solvent Mixture Research Articles

Liquid electrolytes containing new tailored salts for sodium-ion batteries

Sodium 4,5-dicyano-2-(pentafluoroethyl)imidazolate (NaPDI) and 4,5-dicyano-2-(trifluoromethyl) imidazolate (NaTDI) were tested in order to find the optimal solvent mixture composition for possible application in sodium battery electrolytes. The chemical structure of the above imidazolate salts is based on the stable imidazolium ring architecture substituted with electrophilic groups via carbon atoms. It has been shown here that electrolytes with these new salts exhibit high conductivity at room temperature and excellent electrochemical stability up to 4.5V vs. sodium metal. Moreover, both salts are not corrosive to Al foil. The high performance of the new electrolytes in sodium battery technology was also confirmed by compatibility tests carried out with NaxCoO2 cathode materials.

Fabrication and characterization of poly(3-hydroxybutyrate) gels using non-solvent-induced phase separation

Abstract Chloroform (CF) solutions of biodegradable poly(3-hydroxybutyrate) (PHB) formed organogels upon the addition of tetrahydrofuran (THF) as a non-solvent at room temperature. Conformational changes of PHB chains during gelation were monitored in situ by time-dependent infrared spectral (IR) measurements. Analysis of the IR spectra for different wavenumber regions (C H, C O, and C O C stretching vibration regions) showed that PHB chains underwent a molecular transition from a random coil to a helix indicating formation of a crystalline phase following a liquid−liquid phase separation during gelation. Applying solvent exchange and freeze-drying processes to the as-produced organogels allowed fabrication of nanofibrous PHB monoliths with high porosity (∼97%) and surface areas up to 72.1 ± 0.6 m2/g. It was shown that by varying the solvent mixture composition (THF/CF ratio), the gelation kinetics, crystallization behavior, nanofibrous structure, pore character, surface area, and the mechanical properties of PHB aerogels, were effectively controlled.

Composition Dependence of Relative Permittivities of Binary Solvent Mixtures

Binary solvent mixtures exist as liquids over a wide range of temperatures and pressures. For the rational use of the solvent mixtures it is essential to know their physical and chemical properties as functions of their composition and the ambience. The excess functions of physical constants (∆X sln E) can be represented in the polynomial form of the molar fraction (x 2) of the cosolvent by the empirical Redlich-Kister equation.The equation clearly satisfies the condition that ∆X sln E is zero at x 2 = 0 and at x 2= 1. The physical constants of solutions include relative static permittivity, refractive index, viscosity, vaper pressure, etc. The relative permittivity reflects the ease with which dielectric polarization proceeds. The relative permittivity is a measure of the solvent’s ability to insulate opposite charges from each other and has a very significant effect on the strength of the interactions between ions especially in dilute solutions. Electrostatic attractions and repulsions between ions are smaller in solvents with higher relative permittivities.We consider a binary solvent mixture containing molecules “1” and “2”. The numbers of the molecules “1” and “2” are N 1 and N 2, respectively. Assuming the tetrahedral quadruplets (ijkl) in a liquid state and the random distribution of the solvent molecules, we have derived the equation of the dependence of relative permittivity (ε r sln) on the composition of a binary solvent mixture. We obtained the coefficients (ai ) of the relative permittivities in the Redlich-Kister equation. a 0 is a dominant factor governing ∆X sln E. a 0 may reflect the difference in the cooperative orientation polarization between the same and different types of dipoles. a 1 and a 2 may represent the difference in the contribution of the two components to the cooperative orientation polarization.We investigated the relative permittivities (ε r sln) and excess relative permittivities (∆ε r sln E) of binary mixtures of ethylene carbonate (EC) and linear carbonate as a function of the composition at 25 ºC. The symbol x 2 denotes the molar fraction of a low-viscosity solvent: 2-fluoroethyl methyl carbonate (2FEMC) or ethyl methyl carbonate (EMC). EC is a cyclic carbonate, whereas 2FEMC and EMC are linear carbonates. EC and EMC are commonly used as high-polarity and low-viscosity solvents, respectively, for lithium-ion batteries.The equations of the composition dependence of ε r sln and ∆ε r sln E fitted experimental data. The ε r sln of the EC−2FEMC binary mixture was higher than that of the EC−EMC counterpart. The value of a 0 found in the EC−2FEMC binary solvent system (−49) was less negative than that in the EC−EMC binary solvent system (−51). These findings suggest that the amount of the cooperative orientation polarization of the EC−2FEMC binary mixture is larger than that found for the EC−EMC counterpart. The attraction between EC and 2FEMC molecules can be based on nonconventional weak intermolecular hydrogen bonding (CF−H···O or C−H···F−C). The weak hydrogen-bonding system does not exchange its proton and therefore it is no more a genuine hydrogen bond; it is an electrostatic attraction between positive charge on the hydrogen and negative charge on the organic fluorine or the organic oxygen.

Solubility of disodium 4,4′-dinitrobibenzyl-2,2′-disulfonate in aqueous organic solutions and its effects on the oxidation reaction of DSD acid synthesis

The solubility of disodium 4,4′-dinitrobibenzyl-2,2′-disulfonate (DNDNa) in aqueous ethylene glycol monoethyl ether solution and aqueous ethylene glycol monobutyl ether solution was measured over the temperature range from 278 to 334 K at atmospheric pressure by a dynamic method. The solubility of DNDNa in aqueous ethylene glycol monoethyl ether solution and aqueous ethylene glycol monobutyl ether solution increased with temperature over all solvent mixture compositions investigated. A synergistic effect on DNDNa solubility was observed with the maximum solubility at solute-free mass fraction of ethylene glycol monoethyl ether w30=0.6003 and solute-free mass fraction of ethylene glycol monobutyl ether w40=0.4054 , respectively. The solubility data were correlated using the electrolyte non-random two-liquid model and model parameters were determined simultaneously. It was found that around 0.4 (solute-free mass ratio) ethylene glycol monobutyl ether solution is suitable as the reaction medium in oxidation 4-nitrotoluene-2-sulfonic acid to 4,4′-dinitrostilbene-2,2′-disulfonic acid. The effect of different aqueous organic solutions on the oxidation reaction was discussed.

Relation Between Solvent Quality and Phase Behavior of Ternary Mixtures of Polymers and Two Solvents that Exhibit Cononsolvency

The phase boundaries of polymer solutions in mixed solvents can be extremely complex due to the many competing van der Waals and associative interactions that can arise in these ubiquitous and technologically important complex fluids. The present paper focuses specific attention on ternary solutions of polymers (B) dissolved in a mixture of two solvents (A, C) that competitively associate with the polymer. We are particularly concerned with explaining the origin of the peculiar phenomenon of cononsolvency in mixed solvents, where a mixture of two individually good solvents behaves effectively as a poor solvent. Our computations are based on a recently developed generalization of Flory-Huggins theory that incorporates the competitive solvation of a polymer by two associating solvents. On the basis of this framework, we evaluate the limit of polymer phase stability (spinodal curves) and the second osmotic virial coefficient [Formula: see text] as a function of temperature and the composition of the pure solvent mixture that is maintained in osmotic equilibrium with the ternary solution. The calculations provide new insights into the miscibility patterns of ternary A/B/C polymer solutions exhibiting cononsolvency.

Solvent-assisted morphology confinement of a nickel sulfide nanostructure and its application for non-enzymatic glucose sensor

Morphology-controlled synthesis of nickel sulfide (Ni3S2) was performed directly on Ni foam using thioacetamide as a sulfur ion source. Various morphologies of nickel sulfide were fabricated using a hydrothermal process by adjusting the solvent composition of ethanol and water. In the water-dominant condition, a dendrite structure was obtained; otherwise, a flaky structure was achieved. A hierarchical cauliflower-like structure was obtained at a solvent mixture composition of 1:1 and was used as non-enzymatic glucose sensor. The hierarchical Ni3S2 electrode showed a high level of electro-catalytic activity toward the oxidation of glucose (16,460μAmM−1cm−2) over a wide range of detection (0.0005–3mM) and a low detection limit (0.82μM) with excellent selectivity in the presence of several electroactive species.

Assembling quantum dots via critical Casimir forces

Programmed assembly of colloidal inorganic nanocrystal superstructures is crucial for the realization of future artificial solids as well as present optoelectronic applications. Here, we present a new way to assemble quantum dots reversibly using binary solvents. By tuning the temperature and composition of the binary solvent mixture, we achieve reversible aggregation of nanocrystals in solution induced by critical Casimir forces. We study the temperature-sensitive quantum-dot assembly with dynamic light scattering. We show that careful screening of the electrostatic repulsion by adding salt provides a further parameter to tune the reversible assembly.

Simultaneous determination of salicylic, 3-methyl salicylic, 4-methyl salicylic, acetylsalicylic and benzoic acids in fruit, vegetables and derived beverages by SPME–LC–UV/DAD

Salicylic and benzoic acid are phenolic acids occurring in plant cells, thus they can be present in fruit and vegetables at various levels. They possess anti-inflammatory and antimicrobial properties, however they may induce symptoms and health problems in a small percentage of the population. Therefore, a low phenolic acid diet may be of clinical benefit to such individuals. In order to achieve this goal, the concentration of these substances in different food and beverages should be assessed. The present work describes for the first time a new method, based on solid phase microextraction (polydimethylsiloxane–divinylbenzene fiber) coupled to liquid chromatography with UV diode array detection, for the simultaneous determination of salicylic acid, 3-methyl salicylic acid, 4-methyl salicylic acid, acetylsalicylic acid and benzoic acid in selected fruit, vegetables and beverages.All the aspects influencing fiber adsorption (time, temperature, pH, salt addition) and desorption (desorption and injection time, desorption solvent mixture composition) of the analytes have been investigated. An isocratic separation was performed using an acetonitrile-phosphate buffer (pH 2.8; 2mM) mixture (70:30, v/v) as the mobile phase. The estimated LOD and LOQ values (μg/mL) were in the range 0.002–0.028 and 0.007–0.095. The within-day and day-to-day precision values (RSD%) were between 4.7–6.1 and 6.6–9.4, respectively.The method has been successfully applied to the analysis of fava beans, blueberries, kiwi, tangerines, lemons, oranges and fruit juice (lemon and blueberry) samples. The major advantage of the method is that it only requires simple homogenization and/or centrifugation and dilution steps prior to SPME and injection in the LC system.

Solubility Measurement and Simulation of Rivaroxaban (Form I) in Solvent Mixtures from 273.15 to 323.15 K

The solubility of active pharmaceutical ingredients in various solvents is crucial to their industrial production and the development to final formulations. In this work, the solubility of rivaroxaban (form I) in the binary solvent mixtures of 1-methyl-2-pyrrolidinone with water, methanol, ethanol, and isopropanol from 273.15 to 323.15 K has been experimentally measured. Meanwhile, the dependence of the measured solubility on the temperature as well as on the composition of solvent mixtures has been simulated by Jouyban-Acree (JA) and nonrandom two liquid (NRTL) equations, respectively. The results show that as to the solubility simulation of the studied system JA and NRTL give average relative deviations of 0.1081 and 0.1064, respectively, suggesting that both JA and NRTL can act as an efficient simulation tool for the solubility of rivaroxaban (form I) in pure and mixture solvents at various temperatures.

Vertical orientation of solvent cast nanofilled PS-b-PEO block copolymer thin films at high nanoparticle loading

We demonstrate selective dispersion of photosensitive electron acceptor phenyl-C61-butyric acid methyl ester (PCBM) in cylinder forming polystyrene-b-poly (ethylene oxide) (PS-b-PEO) block copolymer (BCP). Neat PS-b-PEO is structurally robust to forming vertically oriented nanoscale morphology of PEO cylinders in the PS matrix directly after solvent casting. Varying amounts of PCBM nanoparticles were mixed with PS-b-PEO BCP in solvent mixtures and films were spin cast on UV/ozone treated clean silicon wafers. We studied in detail the BCP morphology orientation effect of different solvents and solvent mixtures for varying PCBM loading (ϕPCBM) in the films, range from 0 to 50 weight percent relative to the BCP. The key accomplishments of this work include vertical orientation control even at large concentration of PCBM ∼30% (w/w) particles relative to polymer mass and preferential segregation of PCBM in PS block via mixed solvent strategy which otherwise is difficult to realize due to segregation of PCBM on polar substrate. We explain the preferential dispersion of particles in films by demarcating limits in terms of critical Hansen solubility parameter. This value is close to the percolation threshold of PCBM, so a conducting polymer matrix can be expected, especially when it is partitioned preferentially in the matrix PS domain. We report changes in PEO cylinder diameter, cylinder center-to-center distance with PCBM incorporation into PS matrix, change of film thickness with overall PCBM incorporation and root mean square roughness of the film surface, for a range of casting solvents, solvent mixture compositions and ϕPCBM. Notably, the film thickness increased as the PCBM content in film was increased for same processing condition, so that domain swelling by nanoparticles was self-adjusting with film thickness increment.

High-yield exfoliation of graphene using ternary-solvent strategy for detecting volatile organic compounds

Despite the great progress in the theory and experimental verification we made in past decade, the practical application of graphene is still hindered by the lack of efficient, economical, scalable, ease-processing exfoliation method. Herein, we propose a facile, low-cost, and efficient liquid-phase exfoliation process using low boiling-temperature solvent mixture to fabricate few-layer graphene in large scale. The Hansen solubility parameter theory was applied to help optimize the composition of solvent mixture. Aqueous-based ternary-solvent mixture, for the first time, was adapted to exfoliate graphene. We demonstrate that the exfoliation efficiency using ternary-solvent mixture surpasses that from binary-solvent approach. The final product concentration after optimization was over 260μg/ml. The concentrated graphene dispersion was used to fabricate gas sensor for detecting volatile organic gases. Taking advantage of large surface area, large number of adsorption sites, and well-preserved basal plane, the mass-produced graphene nanosheets exhibited promising sensing potential toward ethanol and methanol vapors.

Measurement and correlation of the solubility of rivaroxaban (form I) in binary mixtures of ethyl acetate with tetrahydrofuran, N,N-dimethylformamide, and N,N-dimethylacetamide from T = (278.15 to 318.15) K

In this work, the solubility of rivaroxaban (form I) in binary solvent mixtures of ethyl acetate (EA) with N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA) and tetrahydrofuran (THF) was firstly experimentally measured over the temperature range from (278.15 to 318.15)K. Then the measured solubility data were correlated with such semiempirical thermodynamic models as Jouyban–Acree (JA) equation and Buchowski (λh) equation. The crystal form of the residual solids in equilibrium with liquids was identified by powder X-ray diffraction (PXRD). The melting temperature and fusion enthalpy were determined using differential scanning calorimetry (DSC). The results show that, the solubility of rivaroxaban generally increases with the temperature and decreases with the increase in the content of EA in the binary solvent mixtures. Furthermore, when λh equation is used to correlate the solubility of rivaroxaban with the temperature in each solvent mixture, the average relative deviation (ARD) between the experimental and calculated values is about 0.0671, while it is about 0.0905 when JA equation is employed to correlate the solubility with the temperature and the composition of solvent mixtures simultaneously.

Tuning organic carbon dioxide absorbents for carbonation and decarbonation.

The reaction of carbon dioxide with a mixture of a superbase and alcohol affords a superbase alkylcarbonate salt via a process that can be reversed at elevated temperatures. To utilize the unique chemistry of superbases for carbon capture technology, it is essential to facilitate carbonation and decarbonation at desired temperatures in an easily controllable manner. Here, we demonstrate that the thermal stabilities of the alkylcarbonate salts of superbases in organic solutions can be tuned by adjusting the compositions of hydroxylic solvent and polar aprotic solvent mixtures, thereby enabling the best possible performances to be obtained from the various carbon dioxide capture agents based on these materials. The findings provides valuable insights into the design and optimization of organic carbon dioxide absorbents.

Validation of a Combinatorial Approach Toward the Discovery of Electrolyte Formulations for Lithium-Ion Batteries

Combinatorial methods have opened exciting new prospects for screening materials for application in a growing number of technological areas ranging from drug discovery to semiconductors for photovoltaics1,2. These efforts have been paralleled more recently by the use of computers to explore the properties of yet to be synthesized materials incorporating just about every stable element in the periodic table. However, application of these combinatorial techniques to electrolytes for lithium ion batteries have been rather scarce3where optimization of solvent formulations has apparently been performed by coarse trial and error. This contribution describes a unique instrument capable of producing large numbers of electrolyte mixtures involving solvents either currently in use or being considered in the L-ion industry. EXPERIMENTAL All organic solvent formulations were prepared with a programmable non-contact liquid handling instrument (Digilab MicroSYS) using the synQUAD dispensing technique placed inside an Ar (Airgas High Purity) filled high quality glovebox (MBraun UNIlab) to avoid contamination with atmospheric components and reduce safety hazards. During operation, the pressure within the glove box varied between 2.0 and 6.0 mbar. The solvents involved in these studies were all provided by BASF (formerly Novolyte, Independence, OH), and included diethyl carbonate, DEC, dimethyl carbonate, DMC, propylene carbonate, PC ethyl methyl carbonate, EMC and a solution of room temperature solid, ethylene carbonate, EC, in EMC. The composition of all organic solvent mixtures prepared by the combinatorial instrument was assayed using a Hewlett Packard GC/MS (controlled by Xcaliber) equipped with an Rtx-200MS GC column (30 m in length, 0.25 mm I.D. and film thickness equal to 1 μm, RESTEK Corporation). For all the measurements including the standards, 1 μL diluted solvent (1 μL of the solvent mixtures of interest in 1 mL acetonitrile (HPLC purity, Sigma Aldrich) is injected into GC-MS for each run with a 5 μL syringe (Fisher Scientific). Standard curves relating integrated peak area and volume or weight of the solvent of interest in acetonitrile was obtained by running the solvent at four different concentrations. RESULTS AND DISCUSSION Shown in Figure 1 is a typical chromatogram of a solvent mixture, where each of the peaks is associated with an individual solvent as indicated. Figure 2 shows a comparison between the GC/MS analysis and the intended combinatorial ratios for eight different samples. AS evidenced from these data the agreement between the two sets of data .is indeed excellent yielding for a selected specimen average error of only 2.1%. Values for other specimens ranged between 1.2 and 2.1 % providing evidence that the methodology developed displays high degree of accuracy and as such can assist the discovery of new solvent formulations for application in batteries, supercapacitors and redox flow cells. An assessment of the electrochemical performance of mixtures such as those featured in this report is in progress and will be reported in due course. Acknowledgements This work was supported by a grant from BASF (formerly Novolyte, Independence, OH) through a subcontract for the Ohio Third frontier Program. Figure 1

Room temperature synthesis of covalent-organic framework films through vapor-assisted conversion.

We describe the facile synthesis of several two-dimensional covalent–organic frameworks (2D COFs) as films by vapor-assisted conversion at room temperature. High-quality films of benzodithiophene-containing BDT-COF and COF-5 with tunable thickness were synthesized under different conditions on various substrates. BDT-COF films of several micrometer thickness exhibit mesoporosity as well as textural porosity, whereas thinner BDT-COF films materialize as a cohesive dense layer. In addition, we studied the formation of COF-5 films with different solvent mixture compositions serving as vapor source. Room temperature vapor-assisted conversion is an excellent method to form COF films of fragile precursors and on sensitive substrates.

Greener synthetic route for superparamagnetic and luminescent α-Fe2O3nanoparticles in binary mixtures of ionic liquid and ethylene glycol

The composition of IL and EG binary solvent mixture affects the structural, morphological, luminescent and magnetic properties of α-Fe2O3nanoparticles.

Investigation of Solvent Effects on the Reaction of 1-Fluoro-2,4-Dinitrobenzene with Aniline in Molecular-Molecular and Ionic Liquid–Molecular Solvent Mixtures

The solvent effects on the reaction of 1-fluoro-2,4-dinitrobenzene with aniline was studied in various compositions of molecular-molecular solvent mixtures and molecular solvent-2-hydroxyethylammonium formate mixtures as media containing an ionic liquid. A mounting trend with the mole fraction of water in aqueous solution of alcohols up to a maximum at a mole fraction of 0.9 with respect to water was found, but a mild decrease with the mole fraction of ethyl acetate in methanol–ethyl acetate mixtures. A similar increasing trend was observed with increasing methanol, ethanol, 2-propanol and dimethylsulfoxide content in the mixtures containing the ionic liquid. Solvent effect investigations based on linear free energy relationship confirm that polarity has a major effect in molecular-molecular solvent mixtures, whereas polarity and hydrogen–bond acceptor ability were the dominant factors on reaction rate in molecular-ionic solvent mixtures. A nonlinear free energy relationship based on the preferential solvation hypothesis showed differences between the microsphere solvation of the solute and the bulk composition of the solvents. In these mixtures, the intermediate of the reaction was preferentially solvated by the ionic liquid.

Effect of Dead-Oil Viscosity and Injected-Solvent Type on SVX Process Performance

Summary This work presents experimental results of four 3D-physical-model experiments that were performed to evaluate the dependence of the solvent-vapour-extraction (SVX) recovery process performance on initial dead-oil viscosity and injected-solvent-mixture composition. 0 Model excavation studies were also performed to approximate the solvent movement in the physical model and to map out the residual oil saturation and precipitated asphaltenes. The field-scale application and optimization of SVX processes requires that relationships be established among oil-production rates, solvent usage, and important process parameters (e.g., matrix permeability, initial dead-oil viscosity, solvent-mixture composition, and solvent usage). This work has attempted to generate such relationships for the two most promising mixed-solvent systems being considered for use in heavy-oil reservoirs. The analysis of the experimental results revealed that the initial dead-oil viscosity had a significant effect on the SVX performance. Higher oil-production rates were achieved with the lower-viscosity oils for both injected-solvent-mixture types, with a more-pronounced effect observed when using the CO2/C3 solvent mixture. The results also showed that the CO2/C3 mixture resulted in earlier solvent breakthrough and initial oil production, reduced solvent-makeup requirements (i.e., better solvent recycle stream), and reduced solvent retention in the model/reservoir, as compared with the C1/C3 solvent mixture. The residual-oil-saturation mapping showed that the CO2/C3 mixture led to comparatively lower values in the drained regions and a higher amount of precipitated asphaltenes remaining in the model, although there was evidence of some precipitated asphaltenes close to both the injection and production wells in all four experiments, regardless of the solvent-mixture type. Finally, this mapping also indicated that the solvent/oil interfaces and solvent chambers were more uniform and predictable for the CO2/C3 solvent-mixture injection.

Rotational diffusion of organic solutes in 1-methyl-3-octylimidazolium tetrafluoroborate-diethylene glycol mixtures: influence of organic solvent on the organized structure of the ionic liquid.

Rotational diffusion of two structurally similar organic solutes, 9-phenylanthracene (9-PA) and rhodamine 110 (R110), has been investigated in 1-methyl-3-octylimidazolium tetrafluoroborate-diethylene glycol ([MOIM][BF4]-DEG) mixtures to understand the influence of organic solvent on the organized structure of the ionic liquid. The reorientation times (τ(r)) of nonpolar and charged solutes have been measured as a function of viscosity (η) by changing the temperature (T) as well as the composition of the ionic liquid-organic solvent mixture. These results when analyzed using the Stokes-Einstein-Debye (SED) hydrodynamic theory follow the relationship τ(r) = A(η/T)(n), where A is the ratio of hydrodynamic volume of the solute to Boltzmann constant. However, in neat [MOIM][BF4] and up to 0.4 mole fraction of DEG (x(DEG)), significant deviations from the SED hydrodynamic theory have been noticed with n being much less than unity. As x(DEG) is increased further, the parameters A and n increase considerably for both solutes, and their rotational diffusion follows the predictions of the SED hydrodynamic theory. It has also been observed that the trends in the variation of τ(r) with η/T for 9-PA and R110 are not similar. These observations have been rationalized by taking into consideration the organized structure of the ionic liquid, which gradually becomes homogeneous at the microscopic level with the addition of the organic solvent.

Synthesis of a Polymer Bearing Several Coumarin Dyes along the Side Chain and Study of its Fluorescence in Pure and Binary Solvent Mixtures as well as Aqueous Surfactant Solutions

A copolymer bearing several pendent dyes (coumarin derivatives) along the side chain has been synthesized, and its fluorescence parameters have been monitored in pure solvents and also as a function of composition of binary solvent mixtures. Fluorescence parameters (the maximum energy of fluorescence, quantum yield, and rate constant for the decay of the excited state) of the free fluorophore show significant dependence on the nature of the immediate environment around it. The value of a parameter measured in neat solvent for the fluorophore covalently bound to the polymer is different from that of the free fluorophore, indicating that the polymer chain influences the spectroscopic properties of the dye. Whereas the energy of maximum fluorescence of the free fluorophore shows a nonlinear correlation with the solvent composition of solvent mixtures, an almost linear correlation has been observed for the polymer. A significant variation of photophysical parameters of the dye dissolved in binary solvent mixtures, which is different from that of the free fluorophore, has been observed. Thus, the free fluorophore and the fluorophore bound to the polymer sense different environments in binary solvent mixtures. A dramatic variation of fluorescence intensity of the fluorophore bound to the polymer has been observed when sodium dodecyl sulfate (SDS) is added to an aqueous solution of the polymer. The results have been explained in terms of the existence of different species (polymer, polymer-SDS aggregates, micelles) in equilibrium in solution.