A versatile reagent to synthesize diverse ionic liquids ranging from small molecules and dendrimers to functionalized proteins

An ionic liquid “reagent” bearing a succinimidyl activated ester is reported that can be used to synthesize a variety of small molecule and macromolecular ionic liquids. In addition, the ionic liquid reagent was used to modify lysozyme, and the protein retained its structure and function after modification. This study describes a facile and reliable route to new ionic liquid compositions

Influence of Phosphonium Alkyl Substituents on the Rheological and Thermal Properties of Phosphonium-PAA-Based Supramolecular Polymeric Assemblies

A noncovalent synthetic strategy to supramolecular polymeric assemblies, including network structures, is described by the complexation of various phosphonium monocations and dications with the multianion, poly(acrylic acid). The alkyl chains surrounding the phosphonium cation were systematically varied from butyl, hexyl, to octyl in order to probe the effect of sterics and ion pairing on the resulting macroscopic properties of the assemblies. The supramolecular assemblies were characterized by TGA, DSC, oscillatory rheometry, steady-state flow rheometry, and SAXS. The rheological and thermal properties, as well as the flow activation energies, are highly dependent on the alkyl chain length. All of the supramolecular assemblies have glass transition temperatures lower than room temperature and range from 8 °C to below −40 °C. Di-ButC10PAA has the shortest alkyl chain length and affords the highest glass transition temperature. Correspondingly, it shows the largest viscosity and storage and loss moduli. For example, its viscosity is 3 orders of magnitude greater than di-OctC10PAA. In creep-recovery experiments, di-ButC10PAA shows the highest percent of strain recovery after the stress is removed, followed by di-HexC10PAA and di-OctC10PAA. The rheological and thermal properties of monoIL-PAA assemblies show similar alkyl chain length dependence, but the magnitude is significantly less because of the lack of cross-linking. A reversibility test of the supramolecular networks demonstrates that the ionic network material can fully reassemble within a short time period after disruption of the network due to heat or shear without sacrificing the mechanical properties

From Brittle to Pliant Viscoelastic Materials with Solid State Linear Polyphosphonium–Carboxylate Assemblies

A polystyrenylphosphonium polymer was synthesized and complexed with various carboxylic acid derivatives to form new solid-state polyelectrolyte-surfactant assemblies. The properties of these ionic materials were highly dependent on the nature of the anion and included a brittle material, a rubbery ball that bounces, or a sticky fiber. The values for the equilibrium modulus, storage modulus, and loss modulus were dependent on the composition of the carboxylic acid and the number of electrostatic interactions. Small-angle X-ray scattering studies on the supramolecular assemblies confirmed a bilayer structure for two of the assemblies