| Ionic liquids (ILs) are becoming a novel type of green solvents since its excellent dissolving capacity, diversity of structure and properties, low volatility, high thermal stability and other advantages. As radical polymerization solvent, ionic liquids could increase the propagation rate constant kp and reduce the chain termination rate constant kt, and higher yield and higher molecular weight were obtained as well. Ionic liquids could act as various components in the formation of microemulsion, improving the properties of microemulsion system and expanding its scope of application. Ionic liquid based microemulsion provides an innovative medium for the synthesis of nano-materials, polymer particles, polyelectrolyte materials, polymer composites, which shows a great appeal and application potential. Based on the existing research results, a series of IL-in-oil microemulsion systems, where ILs used as polar phase, were constructed in this dissertation and polymerization reactions in IL-in-oil microemulsion system were investigated in detail. The main contents of this dissertation are as follows:1. The solubilizations of ILs/ILs-monomer in TX-100/cyclohexane system were investigated, and the construction method of the polymerization system in the ionic liquid reverse microemulsion was studied. Firstly, a series of imidazolium ionic liquids were selected, and the solubilizations of their acrylamide solution in TX-100/cyclohexane system were investigated with temperature variation. It indicated that, in a certain temperature range, the solubilization of all types of ILs increased with increasing temperature. The order of ILs-AM solubilization showed as: EmimAc> BmimBF4＞BmimPF6> EmimTfO> BmimCF3OAc> BmimSCN. Wherein, the solubilizations of EmimAc and BmimBF4were significantly higher than others. On this basis, suspension polymerization of acrylamide was tested in the alternative ionic liquid EmimAc and BmimBF4. Polyacrylamide was successfully obtained in BmimBF4system, while the yield of EmimAc system was very low, even polymerization reaction was unlikely to occur. Follow-up studies of the selected system--BmimBF4/TX-100/cyclohexane was preceded. When the internal phase changed from pure IL to the IL-AM solution, the solubilization of IL decreased, and R-value gradually decreased with the increase of monomer concentration; as monomer concentration increased in IL solution, the monomer mass fraction of the whole system showed an increasing tendency; the solubilization of mixed internal phase—Rm decreased with the rise of monomer concentration. When the IL internal phase replaced by IL-AA solution, the solubilization of IL decreased, and R-value gradually decreased with the increase of monomer concentration; as monomer concentration increased in IL solution, the monomer mass fraction of the whole system showed an increasing tendency; the solubilization of mixed internal phase—Rm was influenced both by solubilized AA and IL portion, offering upgrade firstly than descending latter tendency. Compared with acrylamide system, acrylic acid microemulsion system showed a higher solubilization and a wider adjustable range.2. The reaction conditions and laws of BmimBF4-AM/TX-100/cyclohexane system were studied. The results showed that, this was a suspension polymerization process which initiated by ionic liquid microemulsion. The obtained PAM particles had a narrow size distribution with average diameter of about270nm. A study was carried out concerning the effects of different reaction conditions on molecular weight of product:with increased dosage of initiator, molecular weight first increased and then decreased, and the highest weight average molecular weight reached up to106; with the rise of monomer concentration, both weight average molecular weight and number average molecular weight increased significantly; in the investigated temperature range (50～70℃), the molecular weight of PAM offered upgrade firstly than descending latter tendency.3. In this section, BmimBF4-AA/TX-100/cyclohexane inverse microemulsion polymerization system was constructed, and then product post-processing method and influences of reaction conditions on the product were explored. Research showed a microemulsion polymerization process achieved without nitrogen inlet and low molecular weight, monodispersed PAA product obtained. It indicated that:under the same conditions, the molecular weight of PAA increased with the increasing of Rm(0.174～0.36), and all products were characterized with monodispersity; as initiator increased, the molecular weight offered upgrade firstly than descending latter tendency, and the dispersion coefficient tends to be wider at high initiator dosage; higher molecular weight was obtained since the crease of monomer concentration (10-30%), while the molecular weight distribution tends to be wider under high temperature. |
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