Recently, our group successfully developed two new polymerization methodologies for monomers containing two cycloalkene moieties. These polymerization methods yielded well-defined polymers via a combination of ring-opening and ring-closing metathesis (cascade polymerization) or ring-opening, ring-closing, and cross-metathesis (multiple olefin metathesis polymerization (MOMP)) using a second monomer. However, cascade polymerization had some limitations such as low polymerization efficiency (maximum turnover number (TON) of 250) and narrow monomer scope. Furthermore, one-shot MOMP also showed a very narrow monomer scope because of certain undesired side reactions. To overcome these problems, we designed various new monomers containing cyclopentene and even more challenging ring-strain-free cyclohexene moieties, so that polymerization would produce a thermodynamically favored six-membered-ring backbone repeat unit. With this enhanced driving force for polymerization, these new monomers successfully underwent cascade polymerization with a high polymerization efficiency, leading to a maximum TON of 1940 and maximum number-average molecular weight ( M) of 343 kDa. Lastly, one-shot MOMP, which uses all three types of metathesis transformations in a single step, was possible with these monomers and gave highly A,B-alternating copolymers with high selectivity as well. This was possible because the newly designed monomers with the appropriate thermodynamic and kinetic preferences suppressed undesired polymerization pathways and reduced defects in the polymer microstructures. In short, we present our strategies for achieving superior cascade polymerization and MOMP using these new monomers.

A facile and chemical specific method to synthesize highly reduced graphene oxide (HRG) and Pd (HRG@Pd) nanocomposite is presented. The HRG surfaces are tailored with amine groups using 1-aminopyrene (1-AP) as functionalizing molecules. The aromatic rings of 1-AP sit on the basal planes of HRG through π-π interactions, leaving amino groups outwards (similar like self-assembled monolayer on 2D substrates). The amino groups provide the chemically specific binding sites to the Pd nucleation which subsequently grow into nanoparticles. HRG@Pd nanocomposite demonstrated both uniform distribution of Pd nanoparticles on HRG surface as well as excellent physical stability and dispersibility. The surface functionalization was confirmed using, ultraviolet-visible (UV-Vis), Fourier transform infra-red and Raman spectroscopy. The size and distribution of Pd nanoparticles on the HRG and crystallinity were confirmed using high-resolution transmission electron microscopy and powder X-ray diffraction and X-ray photoelectron spectroscopy. The catalytic efficiency of highly reduced graphene oxide-pyrene-palladium nanocomposite (HRG-Py-Pd) is tested towards the Suzuki coupling reactions of various aryl halides. The kinetics of the catalytic reaction (Suzuki coupling) using HRG-Py-Pd nanocomposite was monitored using gas chromatography (GC). The highly reduced graphene oxide (HRG) with its exceptional physicochemical properties is among extensively studied materials in the world 1,2. It is the strongest, thinnest and stiffest material with several remarkable properties, including high thermal and electric conductivities and large theoretical specific surface area 3,4. These unique properties have attracted the vigil eye of researchers in both scientific (academics) and engineering communities (industrial applications) 5. Currently, several methods have been applied to obtain bulk quantities of defect free graphene, which are mainly classified into the bottom-up and top-down approaches 6,7. The most popular methods under the bottom-up approaches include chemical vapor deposition (CVD), chemical conversion, and arc discharge 8,9. Whereas, the top-down approach involve, the sequential oxidation and reduction of graphite. These chemical methods (top-down approaches), offer excellent opportunities for the production of large quantities of graphene like materials, which is best known as highly reduced graphene oxide (HRG) 10,11. The recent advancement in the synthesis of homogeneously dispersed graphene using different reduction and functionalization techniques, have led to the development of various graphene based hybrid materials, such as graphene-inorganic nanoparticles (NPs) based nanocomposites 12,13. The hybridization of inorganic NPs with graphene further enhance the properties and broaden the applications ranging from the medical to the energy

Thermal decomposition is a promising route for the synthesis of metal oxide nanoparticles because size and morphology can be tuned by minute control of the reaction variables. We synthesized CoO nanooctahedra with diameters of ∼48 nm and a narrow size distribution. Full control over nanoparticle size and morphology could be obtained by controlling the reaction time, surfactant ratio, and reactant concentrations. We show that the particle size does not increase monotonically with time or surfactant concentration but passes through minima or maxima. We unravel the critical role of the surfactants in nucleation and growth and rationalize the observed experimental trends in accordance with simulation experiments. The as-synthesized CoO nanooctahedra exhibit superior electrocatalytic activity with long-term stability during oxygen evolution. The morphology of the CoO particles controls the electrocatalytic reaction through the distinct surface sites involved in the oxygen evolution reaction.

Preventing bacteria from adhering to material surfaces is an important technical problem and a major cause of infection. One of nature’s defense strategies against bacterial colonization is based on the biohalogenation of signal substances that interfere with bacterial communication. Biohalogenation is catalyzed by haloperoxidases, a class of metal-dependent enzymes whose activity can be mimicked by ceria nanoparticles. Transparent CeO2/polycarbonate surfaces that prevent adhesion, proliferation, and spread of Pseudomonas aeruginosa PA14 were manufactured. Large amounts of monodisperse CeO2 nanoparticles were synthesized in segmented flow using a high-throughput microfluidic benchtop system using water/benzyl alcohol mixtures and oleylamine as capping agent. This reduced the reaction time for nanoceria by more than one order of magnitude compared to conventional batch methods. Ceria nanoparticles prepared by segmented flow showed high catalytic activity in halogenation reactions, which makes them highly efficient functional mimics of haloperoxidase enzymes. Haloperoxidases are used in nature by macroalgae to prevent formation of biofilms via halogenation of signaling compounds that interfere with bacterial cell–cell communication (“quorum sensing”). CeO2/polycarbonate nanocomposites were prepared by dip-coating plasma-treated polycarbonate panels in CeO2 dispersions. These showed a reduction in bacterial biofilm formation of up to 85% using P. aeruginosa PA14 as model organism. Besides biofilm formation, also the production of the virulence factor pyocyanin in is under control of the entire quorum sensing systems P. aeruginosa. CeO2/PC showed a decrease of up to 55% in pyocyanin production, whereas no effect on bacterial growth in liquid culture was observed. This indicates that CeO2 nanoparticles affect quorum sensing and inhibit biofilm formation in a non-biocidal manner.

NaCrO2 particles for high-rate sodium ion batteries were prepared on a multigram scale in segmented flow from chromium nitrate and sodium nitrate using a segregated flow water-in-oil emulsion drying process....