Synthesis And Properties Of Anionic Gemini Surfactants Without Spacer Groups

Spacer groups play a crucial role for constructing different Gemini surfactants.But with the disappearance of the spacer groups, the distance between the hydrophilicmoieties has been greatly reduced, the properties will also change. So far, the studiesof Gemini surfactants without Spacer groups have been few reported.1. By linking the spacer groups and the hydrophobic chain first, and thenhydrophilic groups, this test synthesized three different types of anionic Geminisurfactant without Spacer groups: sulfate salt Gemini with alkyl group of hydrophobicchain, sulfate salt Gemini with hydrophobic chain connectioning carboxylate, andcarboxylate salt Gemini with hydrophobic chain connectioning carboxylate. Allcompounds were characterizationed by IR,1HNMR and elemental analysis, proved tobe the target products.2. When n=12and n=14, the CMC values of sulfate salt Gemini with alkylgroup of hydrophobic chain are0.079mM and0.018mM, comparing with theircorresponding single-chain surfactants’ CMC values are33mM,8.7mM. The Geminisurfactants are small2to3magnitudes than the single-chain surfactants, indicatingthat the generating capability of Gemini surfactants without Spacer groups is strongerthan the corresponding single-chain surfactants. At the same time, the growth of chainlength will help generate micelles.3. When n=9and n=11, the γcmcof sulfate salt Gemini with hydrophobic chainconnectioning carboxylate are38.97mN·m1and38.30mN·m1, indicating that withthe growth of carbon chain, the ability of reduce the surface tension would beenhanced.4. When n=10,12and14, the CMC values of carboxylate salt Gemini withhydrophobic chain connectioning carboxylate are0.046mM,0.044mM and0.042mM,comparing with their corresponding single-chain surfactants’ CMC values are20.8mM,4.3mM,0.9mM. The Gemini surfactants are small1to3magnitudes thanthe single-chain surfactants, indicating that the generating capacity of Geminisurfactants without Spacer groups is stronger than the single-chain surfactants. At thesame time, the growth of chain length will help generate micelles. 5. From the study of rheological properties and wormlike micelles properties inC12TABr/d-C12CS mixed solution, the conclusion can be reach that anionic Geminisurfactant d-C12CS can be induced by the oppositely charged C12TABr to formwormlike micelles. When the molar ratio of C12TABr to d-C12CS is0.25, the solutionhas the characteristic of viscoelastic Maxwell fluid, and the zero-shear viscosity is600Pa s, which is highest and as five times as that of the single d-C12CS solution. In thissystem, the longest wormlike micelle formed is reckoned to be0.45-0.85μm.