The Regulation Of Ionic Liquids On The Phase Behavior And Self-assembly Of The Block Copolymer 10R5 In Aqueous Solution

Because the hydrophobicity or hydrophilicity of each segment in block polymer is different, the block copolymer can self-assemble into various microstructures in water. Many means to regulate the microstructure of polymer in water, such as temperature, pH, light, inorganic salts, surfactants, organic solvents, alcohols, and the molecular structure of the polymer itself, were explored and great progress has been made. However the study about the regulation of ionic liquids on the phase behavior and aggregation behavior of polymer in water is scarce. As a part of the project supported by the National Nature Science Foundation of China(No.21203057), in this project, we have systematically investigated the influence of the cation’s structure, anions type, and the concentration of the ionic liquids on the phase behavior and aggregation behavior of the polymer in aqueous solutions. This information will provide a scientific basis for the application of ionic liquids in polymer science. The main contents of this paper are as follows:1. The critical solution temperature of the block copolymer [PPG]8-[PEG]22-[PPG]8(10R5) in water was investigated. In addition, the influence of ionic liquids([C2mim]Cl, [C2mim]Br, [C2mim]I, [C2mim][BF4], [C2mim][SCN], [C2mim][EtOSO3], [C4mim]Cl, [C4mim]Br, [C6mim]Cl, [C8mim]Cl, EAN, [P4,4,4,4]Br, [C4mpyr]Br and [C4mpyrr]Br) on the critical solution temperature of polymer 10R5 in water was also investigated. It was found that [C2mim]Cl, [C2mim]Br and [C2mim][EtOSO3] have salt-out effect on the phase behavior of Pluronic 10R5+water system and reduces the LCST values, but EAN, [C2mim][SCN], [C2mim][BF4], [C4mim]Br, [C4mpyr]Br, [C4mpyrr]Br, [C6mim]Cl, [C8mim]Cl and [P4,4,4,4]Br have salt-in effect on the phase behavior of Pluronic 10R5+water system and enhance the LCST values. More interestingly, [C2mim]I exhibits salt-out effect on the phase behavior of Pluronic 10R5+water system in low IL concentration, but exhibits salt-in effect in high IL concentration.2. The aggregate size and the critical micelle concentration(CMC) of 10R5 in aqueous IL([C2mim]Cl, [C4mim]Cl, [C6mim]Cl, EAN, [P4,4,4,4]Br, [C4mpyr]Br, [C4mpyrr]Br and [C4mim]Br) solutions were determined by dynamic light scattering and surface tension. The effect of structure of the cation, the length of the alkyl chain and the concentration of the ionic liquids on the CMC and aggregate size of block copolymer 10R5 in water was analyzed. In addition, according to the thermodynamic equation, the thermodynamic parameters in the process of micelle formation of the polymer, such as ΔG0、ΔH0、ΔS0 were calculated. Then the effect of the cationic structure and the alkyl chain length on these parameters was determined.3. The influence of ionic liquids([C2mim]Cl, [C2mim]Br, [C2mim]I, [C2mim][EtOSO3], [C2mim][BF4] and [C2mim][SCN]) on the critical micelle concentration and aggregate size of polymer 10R5 was determined by dynamic light scattering and surface tension technology. The reason of the effect of anions in ionic liquids on CMC and aggregate size of polymer 10R5 in water was analyzed. The controlling factors on the micelle formation process of polymer micelle were determined.