Influence of different alkyl‐methylimidazolium tetrafluoroborate ionic liquids on the structure of pebax^® films. Consequences on thermal, mechanical, and water sorption and diffusion properties

Abstract

In this work, three ionic liquids (ILs) differing by the length of the alkyl chain linked to their cation were incorporated in a Pebax® copolymer matrix through a solvent cast process for composition from 0 to 70 wt % IL. The copolymer/IL miscibility was investigated via IR Spectroscopy, Differential Scanning Calorimetry and Scanning Electron Microscopy. The three ILs dissolved in the copolymer soft phase for ILs content below 30 wt % whereas they formed segregated dispersed domains at higher loadings. The plasticizing effect of the ILs was examined through DSC and thermomechanical analyses. In the range of IL amount from 0 to 30 wt %, no significant differences were observed in the thermomechanical properties as a function of the IL structure. At higher IL content, the films based on 1‐ethyl‐methylimidazolium tetrafluoroborate sustained better properties. All films exhibited a good thermal stability up to 300 °C. The water sorption isotherms were modeled with GAB equation and both the kinetic and thermodynamic parameters of the sorption mechanism were investigated. A non‐monotonic evolution of the GAB parameters and diffusion coefficient as a function of the IL content was evidenced. Moreover, different behaviors were observed as a function of the IL nature and structuration within the copolymer matrix. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 811–824

Influence of the film‐forming process on the nanostructuration of Pebax®/1‐ethyl‐3‐methylimidazolium triflate ionic liquid: Consequences on the thermal, mechanical, gas, and water transport properties

“…Butan‐1‐ol (purity: 99.7%) was used as supplied by Sigma Aldrich. It was already shown to be a good solvent for both components of the copolymer used in this work …”

“…Pebax® copolymers acquire then their mechanical strength from the hard polyamide domains while elasticity is the result of the polyether soft phase. By varying the composition of the copolymer, Pebax® grades have been adapted to meet the requirements of a wide range of applications going from structural applications to membranes, packaging, or even breathable materials . For these last applications, which are mainly based on the use of films, the control of the material morphology at the microscale and nanoscale is also crucial.…”

“…Although Pebax® copolymers are performant materials, there is still a need to improve their properties to face a growing demand for increasingly specific functional films. Different inorganic or organic species can be added in (co)polymers to enhance their mechanical or functional properties . A great attention has been paid these last years on the use of ionic liquids (ILs).…”

“…Some of them, such as imidazolium‐based ILs have been shown to be particularly interesting for gas separation . Although, some works have consisted in introducing various imidazolium‐based ILs in Pebax® matrices for tailoring their gas or water transport properties, according to our knowledge, no detailed study has been focused on the effect of IL adding on the Pebax® copolymer nanostructure.…”

“…Dense films were prepared by solvent cast process and melt blending process for IL content ranging from 0 to 30 wt % to avoid formation of separated IL domains. Indeed, several studies have shown that this phenomenon could easily occur around 40–50 wt % IL in Pebax®+IL systems . The structure and morphology of the prepared films were investigated thanks to small angle neutron scattering (SANS) and differential scanning calorimetry (DSC).…”