Toward alkaline‑stable anion exchange membranes in fuel cells:cycloaliphatic quaternary ammonium‑based anion conductors

Anion exchange membrane(AEM)stability has been a long-standing challenge that limited the widespread development and adoption of AEM fuel cells(AEMFCs).The past five years have been a period of exceptional progress in the development of several alkaline-stable AEMs with remarkable both ex situ and in situ AEMFC stability.Certain cycloaliphatic quaternary ammonium(cQA)(mainly five-and six-membered)based AEMs appear to be among those having the most promising overall performance.In this review,we categorize cQAs as cage-like(such as quaternized 1,4-diazabicyclo[2.2.2]octane,(QDABCO)and quinuclidinium),non-cage-like(such as pyrrolidinium and piperidinium)and N-spirocyclic(such as 6-azonia-spiro[5.5]undecane(ASU)).The degradation mechanisms of categorized cQAs are first elucidated.Through an understanding of how the cations are attacked by strongly nucleophilic OH–,improved structural design of incorporating alkaline-stable cations into AEMs is facilitated.Before a detailed description and comparison of the alkaline stability of cQAs and their respective AEMs,current protocols for the assessment of alkaline stability are discussed in detail.Furthermore,the initial AEMFC performance and fuel cell performance stability based on cQA AEMs are also examined.The main focus and highlight of this review are recent advances(2015–2020)of cQA-based AEMs,which exhibit both excellent cation and membrane alka-line stability.We aim to shed light on the development of alkaline-stable cQA-type AEMs,which are trending in the AEM community,and to provide insights into possible solutions for designing long-lived AEM materials.

STUDIES ON APPARENT KINETICS AND RHEOLOGICAL BEHAVIOR OF EPOXY/ACRYLATE IPNS AS VACUUM PRESSURE IMPREGNATION RESINS

The apparent kinetics and cure behavior of novel interpenetrating polymer networks(IPNs) based on cycloaliphatic epoxy resin(CER) and tri-functional acrylate have been investigated by means of differential scanning calorimetry(DSC) and Fourier transform infrared spectroscopy(FT-IR).The results of DSC measurements show that the curing reaction of the TMPTMA component is much earlier than that of the CER component,which can lead to the formation of the IPNs.In contrast to neat anhydride-CER system,the anhydri...

Research on the Mechanism of Accelerator for Photocurable Resin in 3D Printing

The photopolymerization kinetics of cycloaliphatic epoxide and oxetane with accelerators were investigated with Real-time Fourier transform infrared spectroscopy(RT-FTIR).The consumption rates of epoxy group and oxetane group as a function of time were obtained by monitoring of the absorption peaks in the 789 cm-1 and 981 cm-1.The effect of accelerators type and the accelerating mechanism were discussed.In general,benzyl alcohol and its analogues with electron-donating substituents are useful accelerators for the cationic polymerization of cycloaliphatic epoxide and oxetane.Activated monomer mechanism and free-radical chain-induced decomposition of onium salt cationic photoinitiator account for the observed accelerating effect on the polymerization rate.

Study on the Effect of Carboxyl Terminated Butadiene Acrylonitrile (CTBN) Copolymer Concentration on the Decomposition Kinetics Parameters of Blends of Glycidyl Epoxy and Non-Glycidyl Epoxy Resin

The degradation of the epoxy system was studied for the prepared six blend samples with the incorporation of 0 wt% - 25 wt% carboxyl terminated butadiene acrylonitrile (CTBN) copolymer, on a dynamic basis using Thermo gravimetric analysis (TGA) technique under a nitrogen atmosphere. The blends were prepared by physical mixing and were cured with diamine. The degradation of each sample followed second-order degradation kinetics, which was calculated by Coats-Redfern equation using best-fit analysis. This was further confirmed by linear regression analysis. The validity of data was checked by t-test statistical analysis. From this value of reaction order, activation energy (E), and pre-exponential factor (Z) were calculated. It was found that the activation energy increased with the addition of liquid elastomer.

Synthesis and antiproliferative activity of novel 4-substituted-phenoxy-benzamide derivatives

A series of novel 4-substituted-phenoxy-benzamide derivatives bearing an aryl cycloaliphatic amine moiety were synthesized and evaluated for antiproliferative activity against SW620, HT29 and MGC803 cancer cell lines in vitro. The pharmacological data demonstrated that the majority of target compounds exhibited moderate efficacy in HT29 and MGC803 cell lines. Compound 10 c showed promising inhibition of hedgehog（Hh） signaling pathway in an Hh-related assay. In addition, the superposition pattern of 10 c showed a good fit for a pharmacophoric model generated by Hh inhibitors and provided a basis for further structural optimization.