Oxidative evolution of Z/E-diaminotetraphenylethylene.

We report that Z/E-diaminotetraphenylethylene (Z/E-2NH2-TPE) molecules suffer primarily from oxidative evolution rather than recognized isomerization. The oxide is separated and its structure is deciphered by single crystal X-ray diffraction. The oxidative evolution accompanying the rearrangement is explained through quantum theoretical calculation.

Thermal and mechanical activation of dynamically stable ionic interaction toward self-healing strengthening elastomers.

Biological tissues can grow stronger after damage and self-healing. However, artificial self-healing materials usually show decreased mechanical properties after repairing. Here, we develop a self-healing strengthening elastomer (SSE) by engineering kinetic stability in an ionomer. Such kinetic stability is enabled by designing large steric hindrance on the cationic groups, which prevents the structural change driven by thermodynamic instability under room temperature. However, once heat or external force is applied to disrupt the kinetic stability, the inherent thermodynamic instability induces the SSEs to form bigger and denser aggregates, thereby the material becomes stronger during the healing process. Consequently, the self-healing efficiency of fractured SSEs is as high as 143%. Unlike conventional ionomers whose mechanical properties change with time uncontrollably due to the thermodynamic instability, the SSEs show tunable self-healing strengthening behavior, thanks to the kinetic stability. This work provides a novel and universal strategy to fabricate biomimetic self-healing strengthening materials.

Reaction-induced phase separation in a bisphenol A-aniline benzoxazine-N,N'-(2,2,4-trimethylhexane-1,6-diyl)bis(maleimide)-imidazole blend: the effect of changing the concentration on morphology.

The effect of the concentration changes on morphology was researched by modulating the molar ratio of bisphenol A-aniline benzoxazine (BA-a) and N,N'-(2,2,4-trimethylhexane-1,6-diyl)bis(maleimide) (TBMI); the relationships between the concentration changes, the curing rate, rheological properties, and morphologies of blends were examined in this paper. The cured blends showed different morphologies at different concentrations, and the morphologies changed from a sea-island structure to a bi-continuous structure followed by a homogeneous structure when the molar ratio of BA-a was decreased. This effect was caused by the relative rates of the phase separation and the curing reaction. Meanwhile, from the thermodynamic calculations, it was found that the concentration changes altered the Gibbs free energy, while the miscibility of blends improved after decreasing the BA-a content. Moreover, from the analysis and the Flory-Huggins equation, it was found that the phase separation of BA-a-TBMI-imidazole occurred due to the molecular weights of the components and the large discrepancy between those weights.