Yahia Djaoued

A sustainable, low-temperature solid state synthesis route, steaming-assistant conversion, combining with our earlier developed ’dynamic hard template strategy’, enables the green synthesis of Nb5+-doped anatase TiO₂ inverse opal films, using a sacrificial PS spheres photonic crystal as template. Thus obtained Nb5+-doped anatase TiO₂ inverse opal film features with a pure phase, uniform doping, and a preserved arrayed macroporous structure, which were hard to simultaneously obtain through traditional methods. The inverse opal photon crystal structure renders slow photon effect at a wavelength of ~792 nm, while Nb5+-doping with well crystallization leads to a plasmon resonance effects at ~825 nm. Under the synergism of both physical effects, a remarkable NIR electrochromic performance is demonstrated by an enhanced optical modulation with the change in optical density of 0.30 at 844 nm and optical contrast with 32.3% at 750 nm, an excellent cycling stability with optical retention of 80%/50 cycles, and a high coloration efficiency (34.9 cm2/C).

ε-Caprolactam anionic polymerization with two catalyst-activator systems was evaluated. Temperature and activator type/concentration impact polymer properties. PA6 optimization improves thermoplastic hybrid composite reactive processing economically.

Ti⁴⁺-doped V₂O₅ films with nanowires on top and a dense, long nanorod layer on the bottom were successfully fabricated using the spin-coating route. During the electrochromic cycling, charge transfer resistance (R_ct) decreases while ion-diffusion ability (K_Ω) rapidly drops in the first ten cycles and then levels off. Low R_ct and morphology of nanowires collaboratively improved the electrochromic behavior of Ti⁴⁺-doped V₂O₅ films by enhancing the charge transfer speed and minimizing polarization and dissolution. The obtained Ti⁴⁺-doped V₂O₅ film shows better electrochromic properties than the undoped V₂O₅ film, with a coloration efficiency (CE) of 34.15 cm²/C, coloration time of 9.00 s, and cyclic retention of 82.6% at cycle 100. In contrast, the corresponding values for the undoped V₂O₅ film were 23.57 cm²/C, 13.16 s, and 43.6%.

This study focuses on how catalyst concentration, activator concentration, and initial polymerization temperature impact in‐situ anionic ring‐opening polymerization (AROP) of ω‐lauryllactam. Catalyst and activator roles are fulfilled by NaH and toluene‐2,4‐diisocyanate (TDI), respectively, with varying catalyst/activator ratios to assess the influence of a bifunctional activator on the polymerization process. The materials produced undergo a thorough analysis, with a specific emphasis on solidification time. The examination extends to scrutinizing how different concentrations of catalyst/activator and polymerization temperatures affect crucial physical and chemical parameters. The study identifies NaH‐6 mol%/TDI‐3 mol% as the optimal formulation for solidification among the three explored temperatures. Notably, at 180 and 200°C, PA12 exhibits enhanced monomer conversion when a catalyst/activator ratio of 1.7 or 2 is applied. These findings underscore the significant impact of the catalyst/activator ratio and their individual concentrations on the polymer's final properties. This influence extends to factors such as crystallinity, polymer chain regularity, and dynamic mechanical properties. Additionally, the experimental conditions utilized for anionic polymerization are observed to shape the characteristics of PA12.

Steaming‐assisted conversion route, a new strategy, is first adapted for the synthesis of highly crystallized anatase TiO₂ 2D inverse opal (IO) monolayer films, and then to Nb‐doped TiO₂ and W‐doped TiO₂ 2D IO monolayer films. Pure water, ammonia, or HCl solutions are used as a source of steaming vapor to convert dry films of amorphous TiO₂ IO, NbCl₅/TiO₂, and WCl₆/TiO₂ composite IOs into anatase TiO₂, Nb‐doped TiO₂, and W‐doped TiO₂ IO films. This new strategy renders possible the doping of metal ions within the framework of the anatase TiO₂ IO films under low temperature and liquid‐free conditions. Further, the ordered array structure of the IO films is also effectively retained. The low steaming conversion temperature allows high dopant rates of homogeneously distributed heteroatoms, resulting in Nb doping as high as ≈34%. The thus prepared TiO₂, Nb‐doped TiO₂, and W‐doped TiO₂ anatase IO films are successfully used as active electrodes in the fabrication of electrochromic devices.