Synthesis of crosslinked polystyrene-b-poly(hydroxyethyl methacrylate)-b-poly(styrene sulfonic acid) triblock copolymer for electrolyte membranes

Abstract

Abstract:The synthesis and the characterization of crosslinked ABC triblock copolymer, i.e. polystyrene-b-poly (hydroxyethyl methacrylate)-b-poly(styrene sulfonic acid), (PS-b-PHEMA-b-PSSA) is reported. PS-b-PHEMA-b-PSSA triblock copolymer at 20:10:70 wt% was sequentially synthesized via atom transfer radical polymerization (ATRP). The middle block was crosslinked by sulfosuccinic acid (SA) via the esterification reaction between -OH of PHEMA and -COOH of SA, as demonstrated by FTIR spectroscopy. As increasing amounts of SA, ion exchange capacity (IEC) continuously increased from 2.13 to 2.82 meq/g but water uptake decreased from 181.8 to 82.7%, resulting from the competitive effect between crosslinked structure and the increasing concentration of sulfonic acid group. A maximum proton conductivity of crosslinked triblock copolymer membrane at room temperature reached up to 0.198 S/cm at 3.8 w% of SA, which was more than two-fold higher than that of Nafion 117(0.08 S/cm). Transmission electron microscopy (TEM) analysis clearly showed that the PS-b-PHEMA-b-PSSA triblock copolymer is microphase-separated with a nanometer range and well developed to provide the connectivity of ionic PSSA domains. The membranes exhibited the good thermal properties up to 250 o C presumably resulting from the microphase-separated and crosslinked structure of the membranes, as revealed by thermal gravimetric analysis (TGA).

Synthesis and electrochemical properties of ion exchange membrane based on crosslinked styrene-(2-hydroxyethyl acrylate)-lauryl methacrylate copolymer

“…The dried membrane was annealed at 110 o C for 1 h for a thermal crosslinking reaction in a vacuum oven. 21 To remove unreacted SSA and crosslink residual hydroxyl group, each dry membrane was immersed in 0.5 M GA solution (the mixture contains 50/50 vol% of acetone/water and 1 vol% of hydrochloric acid as a catalyst) for a period of 2 h at room temperature. After the reaction, the membranes were taken out of the reaction solution, washed several times with pure water to eliminate any possible residual HCl and GA, and then dried under vacuum for 24 h. 22,23 Figure 2 shows the crosslinking mechanism of the Sty-HEA-LMA copolymer.…”

Preparation and characterization of a cation exchange membrane using a styrene-hydroxyethyl acrylate-lauryl methacrylate terpolymer

“…The reactant mixture and t-butyl peroxide (PO) as an initiator were then added to the flask with a dropping funnel over 3 h, after which the reaction was continued with stirring for 21 h. After reaction, the unreacted monomers and solvent were removed from the flask using a vacuum pump. 29,30 Preparation of Sulfonated Membranes. The membranes were prepared by crosslinking with blocked isocyanate as a crosslinking agent to improve efficiency of crosslinking reaction because of having many reaction sites compared to the other crosslinking agent.…”

Nanocomposite proton conducting membranes based on amphiphilic PVDF graft copolymer

“…Therefore, many researchers have diverted their interest to the development of alternative proton conducting membranes which can work at elevated temperatures or low humidification conditions. [7][8][9][10][11][12][13] A partially fluorinated polymer electrolyte membrane is an interesting candidate for replacing Nafion because of easy synthesis, a lower methanol permeability and low costs along with electrochemical properties comparable to perfluorinated membranes. [14][15][16][17][18] It is also well known that partially fluorinated polymer electrolyte membranes possess unique properties, such as low surface energy, high chemical and thermal stabilities, and good mechanical properties.…”

“…6 In particular, much efforts have been devoted to the preparation and characterization of proton conducting membranes for fuel cell applications during the last decade. [7][8][9][10][11][12][13] Polymer electrolyte membrane fuel cells convert chemical energy of a fuel and an oxidant directly to electrical energy using electrodes and a proton conducting electrolyte. The most common polymer electrolyte membranes used in fuel cells are perfluorinated polymer membranes, e.g.…”