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Synthesis, properties and applications of tensoactives and functionalized bio-polymers: a green chemistry approach


It is intended in this project to study aspects of synthesis, properties and applications of tensoactives and derivatives of bio-polymers, in particular of cellulose. The first sub-project includes the following aspects of the chemistry of colloids: 1) synthesis of tensoactives which possess variable hydrophilic and hydrophobic groups, including "green" tensoactives based on 2-aminoglucose, and salts of 1-methyl- 3- alquil- imidazolium; 2) investigation of the relationship between the structure of the tensoactive and the properties of its aqueous and non-aqueous solutions, in particular those that are relevant for the applications; 3) determination of the microscopic polarity and structure of ”green" solvents, their binary mixtures, and of interfacial water of aggregated micellars; 4) investigation of the use of classic and green as catalysts of organic reactions. We will study the effects of the tensoactive structure on the following properties of the aggregates formed: critical micellar concentration; degree of dissociation of the tensoactive counter-ion; number of aggregation; micellar morphology and parameters; thermodynamics (free energy enthalpy and entropy) of adsorption (solution/air interface) and micellization. The techniques employed will include: surface tension; conductance; potentiometry; calorimetric titration; IV, RMN, and static and dynamic light scattering. Using solvatochromatic probes, it is intended to investigate the effects of the structure and charge of tensoactives on microscopic polarity, and "effective” concentration of interfacial water. Such properties will be determined by the comparison of the behavior of the probes in the presence of the tensoactives, and outside the micellar domain. However, solvatochromic and thermo-solvatochromic studies of the probes in pure solvents and their binary mixtures are necessary. It is intended to study "classic”, protic and aprotic organic solvents. The ionic compounds, in particular those that are liquid at room temperature are "green” solvents, whose properties, especially polarity, have been little studied. It is intended to study the polarities of these solvents and their mixtures, at various temperatures, using the same probes. The IV of FT, RMN, and static and dynamic light scattering techniques will be used to study the solubilization of binary aqueous mixtures by inverse aggregates of tensoactives. The information desired will be obtained by the analysis of the dependence of the spectroscopic properties of the system on the (binary mixture) / (tensoactive) ratio. The catalysis of chemical reactions by ionic tensoactives originates from: differences between the properties (microscopic polarity and ionic force) of interfacial water and "bulk” water; electrostatic reactions between the reagents and/or the complexes activated and the ionic micellar interface. Such interactions depend on the structures and the charges of the tensoactives and of the species involved in the reaction. It is intended to study the kinetics of reactions of transfer of acyl dependent and/or independent of pH, of esters in solutions of classic and green tensoactives. Details of the micellar effects will be obtained from the parameters of activation, and by the application of the Hammett equation. In the sub-project on polymers, it is intended to study the derivation of cellulose under homogeneous conditions of reaction. Although this method offers a series of advantages over the heterogeneous (industrial) process, it is more complex and of higher cost. The studies envisaged aim to optimize the homogeneous process through the detailed investigation of its three stages: activation of cellulose, dissolution of activated polymer, and subsequent derivatization. It is intended to investigate the relationship between the structural characteristics of the cellulose and the conditions of its derivatization. Such characteristics include the degree of polymerization, the index of crystallinity, the porosity and the polarity of the surface of the polymer. It is intended to use polar and/or ionic liquid electrolyte/aprotic solvent as solvents for the cellulose. This method will be employed for the synthesis of specialty products, for example, mixed esters of cellulose. (AU)

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