One-Step Fabrication of Novel Polyethersulfone-Based Composite Electrospun Nanofiber Membranes for Food Industry Wastewater Treatment

Using an environmentally friendly approach for eliminating methylene blue from an aqueous solution, the authors developed a unique electrospun nanofiber membrane made of a combination of polyethersulfone and hydroxypropyl cellulose (PES/HPC). SEM results confirmed the formation of a uniformly sized nanofiber membrane with an ultrathin diameter of 168.5 nm (for PES/HPC) and 261.5 nm (for pristine PES), which can be correlated by observing the absorption peaks in FTIR spectra and their amorphous/crystalline phases in the XRD pattern. Additionally, TGA analysis indicated that the addition of HPC plays a role in modulating their thermal stability. Moreover, the blended nanofiber membrane exhibited better mechanical strength and good hydrophilicity (measured by the contact angle). The highest adsorption capacity was achieved at a neutral pH under room temperature (259.74 mg/g), and the pseudo-second-order model was found to be accurate. In accordance with the Langmuir fitted model and MB adsorption data, it was revealed that the adsorption process occurred in a monolayer form on the membrane surface. The adsorption capacity of the MB was affected by the presence of various concentrations of NaCl (0.1–0.5 M). The satisfactory reusability of the PES/HPC nanofiber membrane was revealed for up to five cycles. According to the mechanism given for the adsorption process, the electrostatic attraction was shown to be the most dominant in increasing the adsorption capacity. Based on these findings, it can be concluded that this unique membrane may be used for wastewater treatment operations with high efficiency and performance.

Plant-Based Structures as an Opportunity to Engineer Optical Functions in Next-Generation Light Management

This review addresses the reconstruction of structural plant components (cellulose, lignin, and hemicelluloses) into materials displaying advanced optical properties. The strategies to isolate the main building blocks are discussed, and the effects of fibrillation, fibril alignment, densification, self-assembly, surface-patterning, and compositing are presented considering their role in engineering optical performance. Then, key elements that enable lignocellulosic to be translated into materials that present optical functionality, such as transparency, haze, reflectance, UV-blocking, luminescence, and structural colors, are described. Mapping the optical landscape that is accessible from lignocellulosics is shown as an essential step toward their utilization in smart devices. Advanced materials built from sustainable resources, including those obtained from industrial or agricultural side streams, demonstrate enormous promise in optoelectronics due to their potentially lower cost, while meeting or even exceeding current demands in performance. The requirements are summarized for the production and application of plant-based optically functional materials in different smart material applications and the review is concluded with a perspective about this active field of knowledge.

Azo-Dyes-Grafted Oligosaccharides-From Synthesis to Applications

Azobenzenes are photochromic molecules that possess a large range of applications. Their syntheses are usually simple and fast, and their purifications can be easy to perform. Oligosaccharide is also a wide family of biopolymer constituted of linear chain of saccharides. It can be extracted from biomass, as for cellulose, being the principal constituent of plant cell wall, or it can be enzymatically produced as for cyclodextrins, having properties not far from cellulose. Combining these two materials families can afford interesting applications such as controlled drug-release systems, photochromic liquid crystals, photoresponsive films or even fluorescent indicators. This review will compile the different syntheses of azo-dyes-grafted oligosaccharides, and will show their various applications.

Unraveling the surface properties of PMMA/azobenzene blends as coating films with photoreversible surface polarity

Various reports demonstrated that azobenzene derivatives are the chromophore of choice in photoresponsive surfaces showing reversible surface polarity. Hitherto the surface study of coating films based on polymer/azobenzene blends using contact angle measurements remained unexplored. To provide insight into the surface polarity of polymer/dye blend films, poly(methyl methacrylate) (PMMA) blends containing photoresponsive 4-hydroxy-4′-methylazobenzene (AZO1) and 4,4′-dimethylazobenzene (AZO2) as coating films on clear glass substrates are investigated in this work. Contact angle measurements were carried out to unravel the role of substituents in the surface polarity and the orientation of chromophores in the coating matrices before and after UV light (λ_max = 365 nm) irradiation. Changes in water contact angles measured on the PMMA/azobenzene coating films indicated that the surface polarity is reversible as the chromophores underwent reversible trans–cis isomerisation. It has been revealed that the repeated trans–cis isomerisation led to the random reorientation and arrangement of chromophores in PMMA/AZO1 coating films. Then, to indicate the possibility of the disruption of interfacial interactions due to the repeated trans–cis isomerisation processes, as a proof of concept experiment, it is shown that the commercial acrylic-based pressure-sensitive sticker which adhered strongly to the PMMA/AZO1(13) coating film is peeled off from the coating surface after being subjected to a cycle of UV light irradiation for 12 hours, followed by dark conditions for another 12 hours within 14 days. The proof of concept study will lead to more development of smart photoresponsive coating films using simple polymer/dye blends.

A repeated trans–cis isomerisation led to the random reorientation and arrangement of chromophores in PMMA/azobenzene blends as coating films.

Sol-Gel Synthesis of CaTiO3:Pr3+ Red Phosphors: Tailoring the Synthetic Parameters for Luminescent and Afterglow Applications

Two sol-gel synthetic routes for the preparation of CaTiO₃:Pr³⁺ red emitting phosphors were compared, with the aim of producing nanostructured materials with tailored luminescence/afterglow properties. The effect of the synthetic parameters, such as the addition of a stabilizer and calcination temperature, on the structural, morphological, and optical properties was investigated. The desired perovskite phase was obtained at a calcination temperature of 800 °C or higher. Although the use of acetic acid as the chelating agent leads to micrometric particles with heterogeneous composition, the presence of hydroxypropylcellulose (HPC) results in smaller, less aggregated particles as well as in a high phase purity. At the highest HPC content, surface Ca-rich impurities were detected, although no segregated Ca-rich phases were detectable by X-ray powder diffraction analyses. Luminescence properties were found to be positively related to the phase purity of the oxide, with the highest quantum yields at temperatures equal to or higher than 1000 °C. On the contrary, persistent luminescence properties were highest at intermediate calcination temperatures and for samples synthesized with acetic acid. Overall, a notable role of oxygen vacancies resulting from local Ca excess was observed, acting as trap levels promoting longer relaxation pathways. Thanks to the small-sized particles and best steady-state luminescent properties due to a substantial decrease of lattice defects, the HPC synthesis is a promising strategy for light-emitting diode applications. On the other hand, the acetic acid synthesis promoted a higher defect density, which is required for an efficient yield of light emission in the long time range and is thus more suitable for afterglow applications.

Controlling the Reversible Assembly of Liposomes through a Multistimuli Responsive Anchored DNA

We present a novel approach to reversibly control the assembly of liposomes through an anchored multistimuli responsive DNA oligonucleotide decorated with an azobenzene moiety (AZO-ON1). We show that liposomes assembly can be simultaneously controlled by three external stimuli: light, Mg(2+), and temperature. (i) Light alters the interaction of AZO-ON1 with liposomes, which influences DNA coating and consequently liposomes assembly. (ii) Mg(2+) induces the assembly, hence variation in its concentration enables for reversibility. (iii) Double-stranded AZO-ON1 is more efficient than single-stranded AZO-ON1 in triggering the assembly of liposomes and temperature has been used for controllable assembly through DNA thermal denaturation. Our multiresponsive AZO-ON1 represents a unique example in which multiple stimuli can be simultaneously applied to regulate the reversible assembly of liposomes.