Morphology of Poly(Ethylene Oxide)-Rtils Mixtures: Saxs and MD Studies

Poly (ethylene oxide) is one of the few polymers that are soluble in room temperature ionic liquids. These mixtures can find several applications such as polymer electrolytes or separation media. A few years ago, we highlighted the good solvent nature of RTILs towards PEO, using SANS technique [1], and Ribeiro simulated the morphology and dynamics of PEO-rich mixtures [2]. Recently the activities of Watanabe’s [3], Rogers’s [4] and Lodge’s [5] groups focused on the phase diagram of PEO-RTIL binary mixtures, detecting the existence of a Lower Critical Solution Temperature for these systems and screening the role of RTIL’s chemical details on this complex behavior. Here we show recently obtained results from both Small Angle X-ray and Neutron Scattering from PEO-RTILs mixtures at ambient temperature, as a function of polymer concentration, for a variety of RTILs. We screened the role of alkyl chain length, methylation of position 2 in the imidazolium ring and other chemical details of the RTIL on the morphology of the macromolecule, extracting information as interesting as its average size, the persistence length and chain rigidity. [Figure 1] These results have been complemented with MD simulation study of oligo (ethylene oxide) dissolved in C2mimTf2N and C2C1mimTf2N, in order to explore the role of hydrogen bonding on microscopic organization in such mixtures. SAXS data for another polymer/IL mixture (namely PMMA/C2mimTf2N) will also be presented and compared with the findings for PEO/C2mimTf2N.