Fengxiang Zhang

Imidazolium functionalized polysulfone electrolyte membranes with varied chain structures: a comparative study

The alkaline electrolyte membrane (AEM) is one of the key materials for alkaline electrolyte membrane fuel cells. While most studies focus on AEM performance in relation to cation structure, ion exchange capacity (IEC) and membrane architecture (cross-linking, composite, microphase separation), herein we report that AEMs of varied backbone structures and comparable IEC show remarkably different conductivities and alkaline stability. In particular, the AEM of imidazolium functionalized, isopropylene-containing polysulfone exhibits higher conductivity, but lower swelling- and alkali tolerance than those without such a unit. To confirm and mitigate the backbone influence, we grafted the isopropylene-containing polysulfone with imidazolium functionalized side chains. The resulting grafted membrane shows conductivity of 64 mS cm−1 at 80 °C, which is higher than that of the un-grafted AEMs; its stability against water swelling and hydroxide attack is also improved. Our study provides a new understanding on the structure–property correlation of AEMs, and thus is beneficial for designing high-performance electrolyte membranes for an alkaline fuel cell.

Highly branched side chain grafting for enhanced conductivity and robustness of anion exchange membranes

AbstractAs a key component of alkali anion exchange membrane fuel cells, the anion exchange membrane (AEM) needs to have high ionic conductivity and good stability. Herein, highly branched side chain grafted polysulfone AEMs are designed and fabricated via macromolecule-initiated atom transfer radical polymerization of chloromethyl styrene. The highly branched side chain results in increased free volume in the AEM. As a result, the membrane shows significantly improved hydroxide conductivity relative to its un-branched counterpart membrane. Furthermore, the highly branched side chain renders the membrane with better anti-swelling property and improved alkaline stability. These results demonstrate that constructing highly branched side chain architecture is an effective strategy for fabricating AEMs with high conductivity and stability. Graphical abstractHighly branched side chain grafted AEMs were designed and fabricated. The highly branched side chain provides more free volume for facile hydroxide ion transport. It also provides space for water storage and shielding effect for the interior cations, and thus leads to lower swelling and better alkali stability than the linear polymer AEM at a similar IEC.

Synthesis of quaternary phosphonium N-chloramine biocides for antimicrobial applications

The recently developed quaternary ammonium (QA) N-chloramine has been proved to be a promising “composite” biocide with drastically boosted antibacterial efficacy afforded by the QA moiety. In this work, a series of quaternary phosphonium (QP) N-chloramine biocides, covalently combining an N-chloramine moiety and a QP moiety via varied aliphatic methylene units, were synthesized by means of multi-step chemical reactions. Preliminary antibacterial tests against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) showed that the synthetic QP N-chloramine exhibited distinctively higher biocidal efficacy than the QA counterpart. Furthermore, bactericidal tests also indicated that QP N-chloramine with a linker of –(CH2)12– showed the highest biocidal efficacy, suggesting synergistic action between the N-chloramine moiety and QP moiety.