Synthesis Of Oligomeric Gelator,Characterization And Properties Of Molecular Gel

Many solvents can be gelated by some of low molecular weight compounds and oligomeric at low concentrations (typically < 1wt%) and form viscoelastic liquidlike or solidlike materials that are called molecular gels. Such low molecular weight compounds and oligomeric are called "gelator". Gel self-assembles into a well order and three-dimensional construction in the solvent by the force of non-covalence, such as Ï€-Ï€stacking, hydrogen bond, hydrophobic, van der waals force etc.. By design of gelator, a new oligomeric gelator—polyacroleic acid tetraethylammonium(PAATEA) has been synthesized. In the presence of ZnCl₂ , the gels can be formed by PAATEA in many strong polar solvent, for example, methanol, propylene carbonate, water, DMSO. PAATEA is not dissolved in non-polar solvent such as DME, DOL. PAATEA gelator self-assembles into molecular gel by hydrogen bond, ionomer or metal coordination, which was proved by the FT-IR and theoretics analysis. Thermodynamics research showed that the molecular gels formed by PAAEAT have higher TGS than that formed by low molecular gelator. Rheology research showed that the relation between shear stress of gel and rate of rotor conforms to the power law equation Ï„= kγ|.ⁿ and the value of n is less than one. The gel must overcome yield stress Ï„_y before it begins to move. So the gel is a kind of pseudoplastic Bingham fluid. The relation between apparent viscosity of gel and the temperature conforms to McAllister equation. The viscous flow activity free energy is less than zero. The change of the viscosity of gel with time showed that the gel is a kind of thixotropic fluid. The study on the conductivity for the PAATEA molecular gel with LiClO4 showed that the concentration of PAATEA has no influence on the behavior of the conductivity of gels. The relationship between their conductivity and temperature agrees with Arrhenius equation and the free energy is independent of temperature. The transfer behavior in the gel for lithium ions is similar to that in the solution. TEM and SEM results showed that in the presence of ZnCl₂ PAATEA self-assembles into little global construction by the force of melt coordination in the solvent, which self-assemble into tangled ,three-dimension network by non-covalent bond further.