Facile fabrication of raspberry-like polystyrene/ceria composite particles and their catalytic application

Cellulose acetate/polyurethane blend as support matrix with high optical transparency and improved mechanical properties for photocatalyst CeO2 nanoparticles immobilization

Advanced manufacturing technologies for efficient catalytic materials have triggered the rational design of catalysts as well as extensive investigation into preparative methodologies. Herein, we report the preparation of new versatile cellulose acetate/polyurethane (CA/PU) blends for efficient immobilization of CeO2 nanoparticles, the appropriate composition of polymer mixture being chosen after rigorous analysis (SEM, FTIR, optical, mechanical). The band gap energy for hybrid films ranged between 3.02 eV and 2.05 eV, the lowest value being measured for the film with Co-doped CeO2 NPs (B3 film). The best results in photodegradation of methylene blue under visible-light irradiation was attained after 50 min for B3 film (rate constant k = 45.34× 10-3 min-1), while the total mineralization of MB in the same conditions as evaluated by HPLC-ESI MS and TOC analyses was achieved after 90 min. Effect of co-ions (SO42-, Cl- or NO3-) on photocatalytic performance was studied, and scavenger tests were used to identify the active species involved in the photocatalytic mechanism. Also, the photocatalytic efficiency of B3 sample was tested for rhodamine B, metronidazole and 4-nitrophenol degradation. Evaluation of the stability and integrity of hybrid film after 5 catalysis cycles reveal that the photocatalytic potential is retained with no substantial structural changes.

Preparation of stimuli responsive microgel with silver nanoparticles for biosensing and catalytic reduction of water pollutants

Herein, we report poly(N-isopropylacrylamide/2-acrylamido-2-methylpropane sulfonic acid) microgel fabricated with silver nanoparticles. The identification of copolymerization and functional groups in the bare microgel and those fabricated with silver nanoparticles was examined by Fourier transform infrared spectroscopy. The pH and temperature sensitivity of microgels was studied using dynamic light scattering. Thermogravimetric analysis was carried out to study the thermal stability. X-Ray diffraction patterns indicated the amorphous nature of bare microgel and crystalline nature of those containing silver nanoparticles. A bathochromic shift was found in the surface plasmon resonance of silver nanoparticles present in microgel with increase in pH of the medium. Moreover, the microgel containing silver nanoparticles served as an effective catalyst for reducing the toxic nitroaromatic pollutants and carcinogenic dyes. The microgel containing silver nanoparticles also showed good capability to serve as biosensor for the detection of hydrogen peroxide.

Studies on Hydrophobic Silica/Silicone Rubber Composite Microspheres with Dual-Size Microstructures

In this study, a series of microsphere composites were prepared by the hydrosilylation of nanospherical SiO₂ and silicon rubber microspheres. The influence of different host-guest size ratios on the wettability of the SiO₂/silicone rubber composite microspheres was explored. The structures and performance of the composite microspheres were investigated using scanning electron microscopy and contact angle testing. The results showed that the prepared SiO₂/silicone rubber composite microspheres had a raspberry-like structure and exhibited a rose petal effect. When the SiO₂ content was 30%, the water contact angle of the SiO₂/silicone rubber composite microspheres reached a maximum, and 30% was used as the optimal ratio for compounding SiO₂ having different particle diameters with silicone rubber microspheres. Wettability calculations and analyses were performed for the surface with the composite microspheres. The results indicated that the structure with dual-size roughness could significantly improve surface hydrophobicity. As the ratio of the host-guest size increased, the contact angle of the water phase also increased. However, the surface structures of the composite microspheres were not uniform because of the surface chemical composition and the uncontrollable distribution of the small spheres on the surface of the large spheres during compounding. As a result, water droplets appeared in the Cassie-impregnated state on the composite microsphere particle coating, resulting in the phenomenon of high hydrophobicity and high adhesion.

Synthetic strategies for raspberry-like polymer composite particles

The strategies used for the preparation of raspberry-like polymer composite particles are summarized comprehensively.

Interface Interactions in Conjugated Polymer Composite with Metal Oxide Nanoparticles

This study presents the preparation, characterization, and properties of a new composite containing cerium oxide nanoparticles and a conjugated polymer. CeO₂ nanoparticles prepared using the co-precipitation method were dispersed into the conjugated polymer, prepared using the palladium-catalyzed Suzuki–Miyaura cross-coupling reaction. The interface interactions between the two components and the resultant optoelectronic properties of the composite are demonstrated. According to transmission electron microscopy and X-ray absorption spectroscopy, the dispersion of CeO₂ nanoparticles in the polymer matrix strongly depends on the CeO₂ nanoparticle concentration and results in different degrees of charge transfer. The photo-induced charge transfer and recombination processes were studied using steady-state optical spectroscopy, which shows a significant fluorescence quenching and red shifting in the composite. The higher photo-activity of the composite as compared to the single components was observed and explained. Unexpected room temperature ferromagnetism was observed in both components and all composites, of which the origin was attributed to the topology and defects.

Ultrasound-induced radicals initiated the formation of inorganic-organic Pr2O3/polystyrene hybrid composite for electro-oxidative determination of chemotherapeutic drug methotrexate

To dates, the facile synthesis of inorganic-coated organic polymer composite has received greater attention in the order of research fields including advanced materials and electrochemical analysis owing to the complementary or synergistic effects. In this context, Pr₂O₃ and Pr₂O₃ coated polystyrene (Pr₂O₃/PS) inorganic-organic colloidal composite were prepared via ultrasound-induced radicals initiated precipitation and dispersion polymerization methods. The synthesized Pr₂O₃/PS composite was systematically studied by FE-SEM, TEM, EDX, FT-IR, XRD, and XPS analysis. This composite modified glassy carbon electrode (Pr₂O₃/PS GCE) was utilized to construct a novel electrochemical sensor for the detection assay of chemotherapy agent methotrexate (MTA). Under optimal condition, the designed sensor showed outstanding performance for MTA trace level detection over the linear concentration range of 0.01-236 µM with a detection limit of 0.8 nM for MTA. Furthermore, the prepared sensor accomplished excellent stability and relevant reproducibility, in addition to reliable practical assay in real human blood serum and urine samples. Besides, the possible MTA sensing mechanism of Pr₂O₃/PS GCE has been deliberated in detail. Our finding suggested that the developed Pr₂O₃/PS composite might be a favorable material for the fabrication of the high-performance electrochemical sensor.

Double in Situ Preparation of Raspberry-like Polymer Particles

Well-defined raspberry-like poly(styrene- co-4-vinylpyridine)-SiO₂ nanocomposite particles with a diameter of around 200 nm were easily prepared by a double in situ process in nanoemulsion with the water-soluble dye Eosin Y as the stabilizer. During radical polymerization of the nanodroplets comprising styrene, 4-vinylpyridine (4-VP), and tetraethoxysilane (TEOS), the silane phase is expelled from the polymer phase to the oil/water (o/w) interface. In the later polymerization stage, SiO₂ nanoparticles with a size of around 25 nm were produced via the in situ sol-gel reaction of TEOS at the o/w interface promoted by the negatively charged dye. The pyridine moieties in the copolymer fix the SiO₂ nanoparticles on the surface of the polymer particles by electrostatic interactions without any sign of free unbound silica particles as proven by transmission electron microscopy.