"Thiol-ene" crosslinked polybenzimidazoles anion exchange membrane with enhanced performance and durability.

To address the "trade-off" between conductivity and stability of anion exchange membranes (AEMs), we developed a series of crosslinked AEMs by using polybenzimidazole with norbornene (cPBI-Nb) as backbone and the crosslinked structure was fabricated by adopting click chemical between thiol and vinyl-group. Meanwhile, the hydrophilic properties of the dithiol cross-linker were regulated to explore the effect for micro-phase separation morphology and hydroxide ion conductivity. As result, the AEMs with hydrophilic crosslinked structure (PcPBI-Nb-C2) not only had apparent micro-phase separation morphology and high OH- conductivity of 105.54 mS/cm at 80 °C, but also exhibited improved mechanical properties, dimensional stability (swelling ratio < 15%) and chemical stability (90.22 % mass maintaining in Fenton's reagent at 80 °C for 24 h, 78.30 % conductivity keeping in 2 M NaOH at 80 °C for 2016 h). In addition, the anion exchange membranes water electrolysis (AEMWEs) using PcPBI-Nb-C2 as AEMs achieved the current density of 368 mA/cm2 at 2.1 V and the durability over 500 min operated at 150 mA/cm2 under 60 °C. Therefore, this work paves the way for constructing AEMs by introduction of norbornene into polybenzimidazole and formation of hydrophilic crosslinked structure based on "thiol-ene".

Novel Dual-Component Microencapsulated Hydrophobic Amine and Microencapsulated Isocyanate Used for Self-Healing Anti-Corrosion Coating.

Dual component microencapsulated hydrophobic amine and microencapsulated isocyanate were designed and fabricated for self-healing anti-corrosion coating. In this system, novel hydrophobic polyaspartic acid ester (PAE) and isophorone diisocyanate (IPDI) were microencapsulated respectively with melamine-formaldehyde (MF) as shell via in situ polymerization. To reduce the reaction activity between shell-forming MF prepolymer and PAE, another self-healing agent tung oil (TO) was dissolved in PAE and subsequently employed as core material. With field-emission scanning electron microscopy (FE-SEM) and optical microscopy (OM), the resultant microencapsulated IPDI with diameter of 2⁻5 µm showed a spherical shape and smooth surface. More importantly, both the morphology and microstructure of microencapsulated PAE enhanced significantly after addition of TO. Fourier transform infrared spectra (FTIR) analysis confirmed the molecular structure of chemical structure of the microcapsules. Thermal gravimetric analysis (TGA) indicated that both kinds of microcapsules exhibit excellent thermal resistance with the protection of MF shell. Furthermore, the self-healing epoxy coating system containing microencapsulated IPDI and microencapsulated PAE/TO was prepared and investigated. From the micrographs of true color confocal microscope (TCCM), the self-healing coating containing dual-component microcapsules showed excellent self-repairing performance compared to single microencapsulated IPDI system, and the optimal content of dual-component microcapsules in epoxy coating was 20 wt % approximately.

Fabrication and Performance of Composite Microencapsulated Phase Change Materials with Palmitic Acid Ethyl Ester as Core.

Microencapsulation of phase change materials (PCMs) could prevent the leakage of PCMs during solid⁻liquid phase change process. However, their applications are mainly limited by the compactness and thermal stability of the traditional polyurea shell microcapsules. To increase the thermal compactness and thermal stability of PCM microcapsules, tetraethylorthosilicate (TEOS) was employed to form polymer/SiO2 composite shells to enhance the mechanical performance of polyurea and polyurethane microcapsule via interfacial polymerization and in situ polymerization. The morphology and chemical components of the microcapsules were characterized by field-emission scanning electron microscope (FE-SEM) and Fourier transform infrared (FT-IR) spectroscopy, respectively. The thermal properties of the microcapsules were investigated by differential scanning calorimetry (DSC) and thermal gravity analysis (TGA). The results showed the smoothness and compactness of both polyurea⁻SiO2 and polyurethane⁻SiO2 microcapsules enhanced slightly, when compared with that without TEOS addition. Moreover, the SiO2 composite shell had good effect on thermal compactness, as the weight loss rate of polyurea⁻SiO2 microcapsules and polyurethane⁻SiO2 microcapsules decreased 3.5% and 4.1%, respectively.