Aggregation Behavior of Long-Chain Piperidinium Ionic Liquids in Ethylammonium Nitrate

Micelles formed by the long-chain piperidinium ionic liquids (ILs) N-alkyl-N-methylpiperidinium bromide of general formula CnPDB (n = 12, 14, 16) in ethylammonium nitrate (EAN) were investigated through surface tension and dissipative particle dynamics (DPD) simulations. Through surface tension measurements, the critical micelle concentration (cmc), the effectiveness of surface tension reduction (Pi(cmc)), the maximum excess surface concentration (Gamma(max)) and the minimum area occupied per surfactant molecule (A(min)) can be obtained. A series of thermodynamic parameters (Delta G(m)(0), Delta H-m(0) and Delta S-m(0)) of micellization can be calculated and the results showed that the micellization was entropy-driven. In addition, the DPD simulation was performed to simulate the whole aggregation process behavior to better reveal the micelle formation process.