From Polymerizable Ionic Liquids to Poly(ionic liquid)s: Structure-Dependent Thermal, Crystalline, Conductivity, and Solution Thermoresponsive Behaviors

Abstract

This contribution describes the synthesis of 3-alkyl-1-vinylimidazolium bromide ionic liquid monomers (ILMs), ion exchange with bis­(trifluoro­methane)­sulfonimide anion (NTf2 –), and their radical polymerization to a homologous series of poly­(ionic liquid)­s (PILs) containing an imidazolium ion substituted with alkyl chains of different lengths (C2(n=7–11)). Owing to the presence of a long alkyl chain, all the ILMs show crystalline phases whose melting point and melting enthalpy increase sharply with increasing alkyl chain length, and those parameters decrease upon replacing Br– with a NTf2 – anion. In addition to the solid crystalline phase, the ILMs with a Br– ion only show liquid crystalline mesophases above the melting of solid crystals. The corresponding PILs are semicrystalline in nature due to crystallizable alkyl side chain showing similar chain length and counteranion-dependent melting behaviors with poor crystallinity compared to those of ILMs. The formation of strong birefringent crystals of various morphologies including Maltese-cross and ring-banded spherulites is observed for ILMs. However, the corresponding PILs with a Br– ion show crystals with fibrillar morphology with weak birefringence, but surprisingly such fibrils are not observed for PILs with a NTf2 – ion. The influence of structural modulations of ILMs and their corresponding PILs on their ionic conductivities is also investigated. Moreover, PILs with a Br– ion exhibit an upper critical solution temperature (UCST)-type turbid-to-transparent phase transition in CHCl3 with tunable cloud point as observed from turbidity and calorimetric measurements. Such a thermoresponsive solution phase behavior is totally absent for PILs when Br– is replaced with a NTf2 – ion.

Ion transport and relaxation in phosphonium poly(ionic liquid) homo‐ and co‐polymers

“…Ultimately, the decoupling of ion dynamics from segmental motion is the most promising approach to achieve high ionic conductivity in polymer electrolytes at room temperature. Moreover, there have been a series of studies to examine the effect of tuning of cation/anion size, 30,31 position of ions (either in the main chain or in the side chain) of PIL, 19,29,32,33 variation of molecular weight, 18 changing the space between neighboring PIL chains, 13 pressure exerted during conductivity measurement, 1 variation of chain length, 34 glass transition temperature ( T g ), 14,30,35 chain polarity, 36 etc., on the change of ionic transport in PIL systems. Dielectric spectroscopic (DS) technique is reported to be the most popular method to investigate ionic conductivity, ion transport and relaxation mechanism in electrolyte systems 29,37–39 .…”

Synthesis and Characterization of Ionic Graft Copolymers: Introduction and In Vitro Release of Antibacterial Drug by Anion Exchange

“…Polymers 2020, 12, 2159 2 of 14 PILs consist of repeating groups containing ionic pairs in the polymer chain [26][27][28]. They have the unique properties of ionic liquids and exhibit increased mechanical strength and durability [27,[29][30][31]. Ionic liquids (ILs) are mostly defined as green solvents, but nowadays the studies have indicated that some of them can be toxic [32,33].…”

Hierarchical Structures with Double Lower Disorder-to-Order Transition and Closed-Loop Phase Behaviors in Charged Block Copolymers Bearing Long Alkyl Side Groups

“…Long alkyl side groups forming crystalline or LC mesophase are frequently introduced into imidazole-type ionic liquids (ILs), PILs, and PIL microgels. − In this work, the PIL-containing BCPs with −C 22 H 45 long alkyl side groups, i.e., poly­(ethylene oxide)- b -poly­(1-((2-acryloyloxy)­ethyl)-3-docosylimidazolium) with X – as a counterion (PEO- b -P­(AOEDIm-X)), were synthesized. It was found that the breakout crystallization of −C 22 H 45 side groups led to the disordering of both the first- and second-level structures in the PEO- b -P­(AOEDIm-X) BCPs, which are formed by the microphase separation of PEO/PIL blocks and the long alkyl side groups/the other parts of the PIL block, respectively.…”