Sulfonated Poly(Styrene-Isobutylene-Styrene) Grafted With Hexyl- And Butyl-Imidazolium Chloride Ionic Liquids

In this work, novel sulfonated poly(ionic liquid)s block-copolymers based on poly(styrene-isobutylene-styrene) (SIBS) are synthesized for chemical protective clothing (CPC) applications. The synthesis consists of the chloromethylation of SIBS, followed by the incorporation of N-alkylimidazole through chemical grafting, and concluding with sulfonation of the resulting compound. Properties of the membranes are determined as a function of different N-alkylimidazoles (butylimidazole and hexylimidazole) and sulfonation levels (7-23 mol%). Results show that the incorporation of imidazole and sulfonic groups increases the thermal stability of SIBS as well as its water absorption capabilities. The interaction between the ionic moieties in the polymeric matrix allows the formation of hydrophilic nanochannels, which promote the transport of permeants through the membrane. The high water vapor transmission rate (above 2000 g m(-2) day(-1)) and values of selectivity (similar to 50) demonstrate that the breathability of the synthesized membrane is improved while blocking the passage of dimethyl methylphosphonate (simulant of agent Sarin). The above mentioned observations suggest that sulfonated SIBS-PIL's membranes are potential materials for CPC applications.