Enhanced Polymerization Rate and Conductivity of Ionic Liquid-Based Epoxy Resin

Abstract

The kinetics of polymerization of Bisphenol-A diglycidyl ether (DGEBA), a well-known epoxy resin, with two ionic amines 1-(3-aminopropyl)-3-butyl­imidazolium bis­(trifluoro­methyl­sulfonyl)­imide ([apbim]­[NTf2]) and the tetrabutyl­ammonium leucine ([N4444]­[Leu]) have been studied with the use of differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS) at various temperatures. We found many fundamental differences between the progress of this reaction with respect to the classical system (curing of epoxy resin with ordinary nonconducting hardeners). One of the most significant differences is related to the mechanism of polymerization. It is worthwhile to mention that usually the autocatalytic model is used to describe the curing of DGEBA with ordinary amines. However, herein, the kinetic curves followed a clearly exponential shape characteristic of first-order kinetics. We claim that the change in mechanism of polymerization is related to the presence of a conducting amine that acts as both the substrate and the catalyst of this specific chemical conversion. Also, it is presented that the pace of the reaction only weakly depends on temperature, which is reflected in the relatively low activation energy. On the other hand, the degree of monomer conversion stays around 45%–70% as typically reported for the polymerization of DGEBA with nonconducting hardeners. In addition, we measured the time evolution of dc conductivity as the reaction proceeded and observed that a change in this parameter correlates very well with the monomer conversion in contrast to the reaction of nonconducting systems. Finally, ionic conductivity of the resulted cured samples was investigated and found to be quite significant at the glass transition temperature with respect to other polymerized ionic liquids.

Multifunctionality in Epoxy Resins

“…Although the polymers out of these ionic liquid-epoxy systems have relatively high conductivities, still, more work is needed for their industrial use as solid state electrolytes. 150 Nanoparticle alignment in an electric field ( Fig. 11) was observed to influence material conductivity.…”

A General Overview of Support Materials for Enzyme Immobilization: Characteristics, Properties, Practical Utility

“…The greatest advantage of synthetic polymers as support materials is that the monomers that build the polymeric chain can be selected according to the requirements of the enzyme and process in which the product of immobilization will be used [41,42]. The type and quantity of the monomers determine the chemical structure and properties of the polymer.…”

Accelerated weathering studies of bioepoxy/ionic liquid blends: influence on physical, thermo-mechanical, morphology and surface properties

“…The ionic liquid has reportedly proved to exhibit different behavior depending on its amount in epoxy resin [9]. At lower ionic liquid content, it acts as a catalyst or crosslinking agent for epoxy resin [10,11]. The usefulness of ionic liquid as a crosslinking agent is possible either by mixing alone with epoxy resin or in ratios with any other conventional curing agents [12,13].…”