In-situ and real-time nano/microplastic coatings and dynamics in water using nano-DIHM: A novel capability for the plastic life cycle research

A novel nano-digital inline holographic microscope (nano-DIHM) was used to advance in-situ and real-time nano/microplastic physicochemical research, such as particle coatings and dynamic processes in water. Nano-DIHM data provided evidence of distinct coating patterns on nano/microplastic particles by oleic acid, magnetite, and phytoplankton, representing organic, inorganic, and biological coatings widely present in the natural surroundings. A high-resolution scanning transmission electron microscopy confirmed nano-DIHM data, demonstrating its nano/microplastic research capabilities. The sedimentation of two plastic size categories was examined: (a) ∼10 to 700 µm, and (b) ∼ 1 to 5 mm. Particle size was the primary factor affecting the sedimentation for studied (a) microplastics and (b) pellets. Two types of silicone rubbers exhibited different sedimentation processes. We also demonstrated that inorganic ions in seawater and oleic acid organic coatings altered the sedimentation velocity of studied plastics by 9 - 13% and 5 - 9%, respectively. Semi-empirical probability functions were developed and incorporated into a numerical model (CaMPSim-3D) to simulate the transport of studied microplastics and pellets in the Saint John River estuary. Water dynamics was the driving force of plastic transport, yet the accumulation of plastics was selectively dependant on particle physicochemical properties such as size and density by ∼ 7%. The usage of nano-DIHM for targeted identification of nano/microplastic hotspots and aquatic plastic wastes remediation were discussed.

Physical and mechanical properties of hybridized elastomeric foam based on ethylene-propylene-diene-monomer, multiwall carbon nanotube, and barium titanate

The use of hybrid fillers in rubbers can provide additional benefits to rubber foams compared to individual micro- or nano-scale particles due to an optimum packaging and synergic effects. The present work reports the development of vulcanized ethylene-propylene-diene-monomer nanocomposite hybrid foams filled with barium titanate and multiwall carbon nanotube (BT/MWCNT), prepared via a scalable protocol. The developed foams presented a high shear-thinning behavior, suggesting the formation of a 3D interconnected physical network of MWCNT within the polymer matrix. This network resulted in a notable improvement of the mechanical properties under tension and compression with increasing of MWCNT content. Also, the incorporation of MWCNT and BT enhanced thermal stability and thermal conductivity. Meanwhile, BT did not show any influence on the measured physical properties, due to the lack of interaction between BT and the EPDM matrix.

Direct Synthesis of Methyl Chlorosilanes from Pd-Mg-SiO2 Substrates Using Mechanochemistry

The direct reaction of methyl chloride with magnesium and palladium infused silica substrates to synthesize methyl chlorosilanes is reported. First, high energy ball milling on solid Mg-SiO₂ mixtures produces elemental silicon and MgO. When PdCl₂ is infused into the mixture, after additional ball milling and high-temperature reduction under H₂ , dipalladium silicide (Pd₂ Si) is produced. The silicon of the Pd₂ Si readily reacts with MeCl under Müller-Rochow reaction conditions, to produce methyl chlorosilanes at yield ratios analogous to those of the traditional process. The dominant product is Me₂ SiCl₂ (selectivity > 30%), followed by MeSiCl₃ and Me₃ SiCl, with minor amounts of the remaining chlorosilanes. Silicon conversion exceeds 20% for most of the substrates. The elemental palladium, which remains within the Pd-Mg-SiO₂ contact mass is re-converted to Pd₂ Si at the next H₂ /high-temperature treatment and reacts again with MeCl to repeat the methyl chlorosilane production. In principle, the resulting cycle of the mechanochemically induced formation of Pd₂ Si followed by the reaction with MeCl can be repeated until the starting SiO₂ converts completely to methyl chlorosilanes.