Effect of Molecular Weight on Viscosity Scaling and Ion Transport in Linear Polymerized Ionic Liquids

Abstract

A series of acrylic polymerized ionic liquids (PILs) with imidazolium cations and bis­(trifluoromethylsulfonyl)­imide (TFSI) anions were synthesized via reversible addition–fragmentation chain-transfer polymerization. The absolute molecular weights (MWs) of PILs were determined from size exclusion chromatography with light scattering. The degree of polymerization (N) ranged from 15 to 254, and steady rotational rheology indicated the zero-shear viscosity (η0) measured at a constant distance above the glass transition scales as η0 ∼ N 1.0 for N < 92, in agreement with the theory for unentangled polymer melts. In the range from N = 92–254, we measured η0 ∼ N 2.3 which is interpreted as a transition region. The N 1.0 scaling in the unentangled regime is in contrast to the prior report of η0 ∼ N 1.7 in polyethylene-based PILs (Macromolecules, 2011, 44, 7719) but in agreement with a calculated η0 ∼ N 1.1 of acrylic ammonium TFSI PILs (Macromolecules, 2016, 49, 4557). Oscillatory shear rheology revealed that electrostatic interactions in this system were weak enough to have no impact on delaying the onset of flow, which was supported by a lack of ion aggregation in wide-angle X-ray scattering. The polymer nanostructure was also found to be minimally influenced by the degree of polymerization. Ionic conductivity slightly decreased as MW increased but overlapped when normalized to the calorimetric glass transition temperature.

Sugar decorated star-shaped (co)polymers with resveratrol-based core – physicochemical and biological properties

“…Ionic repulsive interactions strongly affects (induce significant increase) of the glass transition temperature of low and high molecular weight soft materials. Such a behavior was already reported for linear poly(ionic liquids) [69]. Therefore, one can suppose that along with increasing concentration of DMAEMA the number of ionic interactions gets lower leading to the depression of the T g [70].…”

Ion Specific, Thin Film Confinement Effects on Conductivity in Polymerized Ionic Liquids

“…The conditions for ion exchange were shown to be sufficient in prior work, and the elemental analysis confirmed that the residual bromide contents for the four PILs were < 0.7 wt % (Table S1). The Im TFSI PIL sample with a number-average degree of polymerization determined by nuclear magnetic resonance ( N NMR ) of 290 was used from the previous study . The Im BF 4 PIL was synthesized from a separate batch of Br PIL with N NMR = 110 (Figure S1a).…”

Ion Specific, Thin Film Confinement Effects on Conductivity in Polymerized Ionic Liquids

“…The synthesis of the bromo-terminated acrylate, the imidazolium Br ionic liquid monomer and the Im Br PIL were previously reported by our group and used without any modification. 1…”

“…The Im TFSI PIL with N NMR =290 was used from previous work. 1 The Im BF 4 PIL was prepared by ion exchange. Im Br PIL (0.198 g, 0.72 mmol Br -) was dissolved in 10mL DI water and added dropwise to a solution of NaBF 4 (0.79g, 7.2 mmol BF 4 -) in 10mL DI water in a 1kDa MWCO dialysis bag.…”

“…Figure S1 1. H-NMR spectra of (a) Im BF 4 PIL with N=110, based on NMR end group analysis (imidazolium protons at 9ppm vs. CH 3 protons on RAFT agent at 0.85ppm), (b) Am TFSI PIL with N=104 based on the ratio of CH 3 protons on side chain end at 0.93ppm vs CH 3 protons on RAFT agent at 0.85ppm.…”