Meihua Liu

Synthesis of glycidyl azide polymers (GAPs) via binary ionic liquid–water mixtures without catalysts

We report the preparation of glycidyl azide polymers (GAPs) by the reaction of a prepolymer polyepichlorohydrin (PECH) with sodium azide (NaN3) in mixture solvents of different mass ratios with ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and water without catalysts. The formation of GAP was confirmed by IR and NMR spectroscopy, and the molecular weight of the product was determined by gel permeation chromatography (GPC). The conversion of PECH was identified via quantitative 13C-NMR spectroscopy. This method avoids solvent pollution and simplifies the reaction post-processing. The reaction was monitored by IR and 13C-NMR. We concluded that the relative solubility of the reaction substrate in the mixed solvents has an important effect on the degree of the reaction.

Kinetics and thermal properties of epoxy resins containing the ionic liquid [C6mim]FeCl4

The 1-hexyl-3-methylimidazole ferrum tetrachloride salt ([C6mim]FeCl4) and mixed amines were blended in different mass ratios with bisphenol-A epoxy resin E-51 to obtain a series of cured products at room temperature. The thermal decomposition of the cured products was studied by thermogravimetric analysis, dynamic mechanical analysis, and in situ Fourier-transform infrared spectroscopy. The thermal degradation temperatures changed as a function of different mass ratios of [C6mim]FeCl4. The kinetics of thermal decomposition were then analyzed by the Flynne–Walle–Ozawa method. The results show that the incorporation of [C6mim]FeCl4 is a better way to improve the performance of room-temperature curing epoxy resins.

DGEBA/imidazolium ionic liquid systems: the influence of anions on the reactivity and properties of epoxy systems

Abstract Imidazolium salts containing , , , , or ionic liquids were blended with an epoxy prepolymer, dyglycidylether of bisphenol A (DGEBA) to obtain a series of compositions. To characterize the resulting mixtures and determine the influence of the imidazolium anion on the reactivity and properties of epoxy systems, we performed the following analyses and tests: (i) differential scanning calorimetry (DSC), to determine the curing reaction characteristics, (ii) in situ fourier-transform infrared spectroscopy (FTIR), to assess chemical structure changes, (iii) mechanical property testing of the hardened epoxy material, and (iv) thermogravimetric analysis (TGA). The DSC and FTIR analyses indicate that [Hmim]BF4, and [Hmim]PF6 cannot induce the epoxy ring opening reaction and thus these materials are unable to function as epoxy curing agents. In contrast, the imidazolium ionic liquids [Hmim]FeCl4, [Hmim]N(CN)2, and [Hmim]Zn2Cl5 independently promote the epoxy ring opening reaction. TGA analyses show that the cured DGEBA/[Hmim]Zn2Cl5 system exhibits thermal stability similar to the cured DGEBA/[Hmim]FeCl4. These results can provide an essential reference not only for studying the synergistic effect of [C6mim]FeCl4/mixed-amines on the curing process of epoxy systems and the mechanism of the ring opening of epoxides with [C6mim]FeCl4/mixed-amines, but also for designing new epoxy curing systems.