Synthesis of highly branched sulfonated polymers and the effects of degree of branching on properties of branched sulfonated polymers as proton exchange membranes

Synthesis and properties of highly branched star-shaped sulfonated block polymers with sulfoalkyl pendant groups for use as proton exchange membranes

“…To evaluate whether the SPAES-6x membranes are capable of withstanding strong oxidizing environments during fuel cell operation, the oxidative stability of the branched membranes was evaluated by measuring the elapsed time before a membrane sample began to disintegrate after immersion in Fenton's reagent (2 ppm FeSO 4 in 3% H 2 O 2 ) at 80°C. As shown in Table 3, the branched SPAES-6x membranes with pendant sulfoalkyl groups exhibited better oxidative stability (4 400 min) than the corresponding linear polymer (210 min) or the branched membranes without sulfoalkyl side chains (280 min) [17,29]. This improved stability is attributed to the branched structure and the flexible side chains, which effectively separate the sulfonic acid groups from the polymer main chain to form highly concentrated hydrophobic domains that prevent or reduce the probability of radical attack, leading to better oxidative stability.…”

“…However, cross-linked membranes are generally insoluble in common organic solvents and are difficult to reprocess, which has restricted their development as commercial membranes. Recently, studies have shown that branching is also an excellent method for this purpose [17][18][19][20][21][22][23]. Compared with cross-linked membranes, branched membranes not only exhibit improved oxidative stability and conductivity but also demonstrate good solubility in common organic solvents [17,19,20].…”

“…However, the mechanical properties of highly branched membranes notably decrease with an increasing degree of branching (DB) and cannot satisfy the requirements for PEMs. This could be because of a decrease in chain entanglement with increasing branching caused by the hard arms and short chains between branching points [17]. polymer, which could help to increase the entanglement of the polymer chain, thus improving its mechanical properties.…”

Synthesis and properties of branched sulfonated polyimides for membranes in vanadium redox flow battery application

“…Due to their unique physical and chemical properties, branched polymer membranes have been demonstrated potential applications in various fields such as direct methanol fuel cell and VRB [18][19][20]. H. Xie et al [21,22] prepared a series of highly-branched polymer membranes, and they reported that the membrane whose degree of branching (DB) was 10% exhibited superior proton conductivity and oxidative stability. L. Wang et al [23] synthesized and prepared several branched SPAE membranes through adjusting the DB value, and they found that the optimum DB was 4% to obtain the membrane with the oxidation stability 3.4 times higher than the linear one.…”

Effect of different ion-aggregating structures on the property of proton conducting membrane based on polyvinyl alcohol

“…5B), the rigid hole-work structure is formed. These holes represent the hydrophilic domains containing water [35][36][37], which is benefit for the water uptake. The pendent-type side chain can drive the ionic clusters to aggregate and the hydration number will increase [38,39].…”