Janus particles by simplified RAFT-based emulsion polymerization process for polymer coating

We describe a simplified method to synthesize film forming polymer Janus particles by phase separation during RAFT-based free radical emulsion polymerization. Fully crosslinked snowman- or football-shaped polystyrene Janus particles (PSJPs) were first produced in a one-step batch process using amphiphilic triblock macro-RAFT copolymers as stabilizers. Such particles were in turn employed as seeds in a continuous emulsion polymerization in which a monomer mixture of methyl methacrylate (MMA) and butyl acrylate (BA) (1/1 by weight) was constantly injected into the reaction in the presence of a water soluble initiator. The added monomers wetted seed particle surface and their polymerization led to formations of 93-nm film forming single- or two-headed Janus particles. The resulted latex was successfully used to disperse and encapsulate solid calcite extender. Graphical abstract

Causality in physical processes

A mathematical model is presented that describes how the diverse phenomena in nature can arise from a common foundation rooted in an objective framework of relational causality. Key equations of conventional physical theories are derived anew. Rigorous derivations are shown for such fundamental relationships as the Schrödinger equation, Bohr’s formula for the hydrogen spectrum, Newton’s gravitational law, Coulomb’s electrostatic law, Compton shift formula, and other principal equations of electromagnetism, atomic theory, optics, and thermodynamics. Nuclear forces that bind nucleons and pry them apart are shown to arise from a single universal electrostatic force that also gives rise to the Coulomb force. Dark matter is shown to be an ever-present material content that subsists in the fabric of space everywhere. The precise value of Coulomb’s constant is derived on purely theoretical grounds, while hitherto unknown values are predicted for the electric dipole moments of electrons and protons. The first of three components of the core hypothesis of this model is that there exists a primordial seed particle of which all that lies in the universe is ultimately composed, and that it is defined by Planck’s constant. Space is modeled as a lattice of contiguous cells that are composed entirely of these particles, and are inherently elastic. The second component is that the universe evolves temporally through a recursive process, emulating a system of cellular automata. The third component stipulates that any compression produced in a cell by its ambient conditions generates potential energy according to classical elasticity. Thus, every cell seeks to minimize its stored potential energy at each step in its temporal evolution, in pursuit of elastic equilibrium. This core hypothesis in respect to the physical character of space, time, and energy is shown to lead logically to a universal dynamic that gives rise to the physical effects observed in nature at every scale.

Temperature and acidity dependence of secondary organic aerosol formation from <i>α</i>-pinene ozonolysis with a compact chamber system

Secondary organic aerosols (SOAs) affect human health and climate change prediction; however, the factors (e.g., temperature, acidity of pre-existing particles, and oxidants) influencing their formation are not sufficiently resolved. Using a compact chamber, the temperature and acidity dependence of SOA yields and chemical components in SOA from α-pinene ozonolysis were systematically investigated under 278, 288, and 298 K temperatures using neutral ((NH4)2SO4) and acidic (H2SO4+((NH4)2SO4)) seed aerosols. SOA components with m/z less than 400 were analyzed using negative electrospray ionization liquid-chromatography time-of-flight mass spectrometry. Based on the slightly negative temperature dependence of the SOA yields, the enthalpies of vaporization under neutral and acidic seed conditions were estimated to be 25 and 44 kJ mol−1, respectively. In addition, SOA yields increased with an increase in the acidity of seed particles (solid/near-solid state) at low SOA mass loadings, when compared with the seed particle amounts. Acidity dependence analysis of the chemical formula, molecular mass, and O:C ratio of the detected compounds indicated the enhanced formation of multiple oligomers in the wide molecular mass range with a wide range of O:C ratios under acidic seed conditions. The peak abundances of some chemical compounds increased with an increase in the acidity of seed particles (e.g., m/z 197, 311, 313, 339, 355, and 383), while decreases in the peak abundances of some chemical compounds were observed (e.g., m/z 171, 185, 215, 343, and 357). The acidity dependence could be explained by acid-catalyzed heterogeneous reactions or acid-catalyzed decomposition of hydroperoxides. In addition, organosulfate (OS) formation was observed under acidic seed conditions. Six out of the 11 detected OSs were potentially formed via the aldehyde + HSO4- pathway.

Hydrogen Abundances and Shock Waves

How well do protons fit into the abundance patterns of the other elements? Protons have Q = 1 and A/Q = 1 at all temperatures of interest. When does their relative abundance fit on the power law in A/Q defined by the elements with A/Q > 2? For small “pure” impulsive events, protons fit well, but for larger CME-associated impulsive events, where shock waves boost the intensities, protons are enhanced a factor of order ten by addition of seed protons from the ambient plasma. During most large gradual SEP events with strong shock waves, protons again fit the power law, but with weaker or quasi-perpendicular shock waves, dominated by residual impulsive seed particle abundances at high Z, again protons are enhanced. Proton enhancements occur when moderately weak shock waves happen to sample a two-component seed population with dominant protons from the ambient coronal plasma and impulsive suprathermal ions at high Z; thus proton-enhanced events are a surprising new signature of shock acceleration in jets. A/Q measures the rigidity dependence of both acceleration and transport but does not help us distinguish the two. Energy-spectral indices and abundances are correlated for most gradual events but not when impulsive ions are present; thus we end with powerful new correlations that probe both acceleration and transport.

Temperature and acidity dependence of secondary organic aerosol formation from α-pinene ozonolysis with a compact chamber system

Secondary organic aerosol (SOA) is of great importance, affecting human health and the prediction of climate change; however, the factors (e.g., temperature, acidity of pre-existing particles, and oxidants) influencing its formation are not sufficiently resolved. In this study, a compact Teflon atmospheric simulation chamber is developed, in which reactions in atmospheric pressure conditions can be performed with controlled temperature, humidity, oxidation agents, and seed particle acidity. Using the chamber, α-pinene ozonolysis SOA formation was simulated under temperatures of 278 K, 288 K, and 298 K with neutral/acidic seed aerosols. The SOA components of m / z less than 400 were analyzed using negative electrospray ionization liquid-chromatography time-of-flight mass spectrometry. The temperature and acidity dependence of SOA yields and chemical components were investigated. From the slightly negative temperature dependence of the SOA yields, the enthalpy of vaporization in neutral and acidic seed conditions was estimated to be 25 and 44 kJ mol−1, respectively. With these values, the volatility distributions of the identified SOA compounds were consistently explained. Acidity dependence analysis of the chemical formula, molecular mass, and O : C ratio of the detected compounds indicated the enhanced formation of many oligomers in the wide molecular mass range with a wide range of O : C ratios under acidic seed conditions. The acidity dependence of certain major compounds could be explained by acid-catalyzed heterogeneous reactions (e.g., m / z 171, 185, 343, and 357) or acid-catalyzed decomposition of hydroperoxides (e.g., m / z 215 and 197). In addition, the formation of organosulfates (OS) was observed under acidic seed conditions. We proposed that six of the eleven detected OS were possibly formed through the aldehyde + HSO4− pathway. Further studies on the OS formation during α-pinene ozonolysis are warranted.

Influence of Ammonium Sulfate Seed Particle on Optics and Compositions of Toluene Derived Organic Aerosol in Photochemistry

Aromatic secondary organic aerosol (SOA) particles are known to contribute to radiative forcing and light absorption of atmosphere. However, the complex refractive index (CRI), single-scattering albedo (SSA) and other optical parameters of aromatic SOA are not well understood. SOA generated from photooxidation of toluene with a variety concentration of ammonium sulfate ((NH4)2SO4) seed particles in a smog chamber were investigated in the current study. The real part CRI of toluene SOA without seeds derived and based on aerosol albedometer measurements is 1.486 ± 0.002 at λ = 470 nm, showing a good agreement with available experimental data, and its SSA was measured to be 0.92 ± 0.02 at λ = 470 nm, indicating that the SOA particles without seeds have strong scattering ability. The SSA of SOA formed in the presence of 300 μg/m3 (NH4)2SO4 seed was 0.81 ± 0.02 at λ = 470 nm, less than the SSA of SOA without seed. SSA of SOA decreased, while the imaginary part of CRI (k) of SOA increased with increasing concentration of (NH4)2SO4 seed, demonstrating that the adsorption capacity of SOA formed in the presence of (NH4)2SO4 seed is enhanced. Different from the carboxyl compounds measured in the SOA without seed, imidazoles with strong chromophores of C=N that are responsible for the light absorption were detected as the principal constituents of SOA formed in the presence of (NH4)2SO4 seed. These would provide valuable information for discussing the optics and components of aromatic SOA in the urban atmosphere containing a high concentration of (NH4)2SO4 fine particles.

Counting on chemistry: laboratory evaluation of seed-material-dependent detection efficiencies of ultrafine condensation particle counters

Condensation particle counters (CPCs) are crucial instruments for detecting sub-10 nm aerosol particles. Understanding the detection performance of a CPC requires thorough characterization under well-controlled laboratory conditions. Besides the size of the seed particles, chemical interactions between the working fluid and the seed particles also influence the activation efficiencies. However, common seed particle materials used for CPC characterizations are not chosen with respect to chemical interactions with vapor molecules of the working fluid by default. Here, we present experiments on the influence of the seed particle material on the detection efficiencies and the 50 % cutoff diameters of commonly used CPCs for the detection of sub-10 nm particles. A remarkable set consisting of six different and commercially available particle detectors, including the newly developed TSI V-WCPC 3789 and a tuned TSI 3776, was tested. The corresponding working fluids of the instruments are n-butanol, diethylene glycol and water. Among other materials we were able to measure detection efficiencies with nanometer-sized organic seed particles reproducibly generated by the oxidation of β-caryophyllene vapor in a flow tube. Theoretical simulations of supersaturation profiles in the condensers were successfully related to measured detection efficiencies. Our results demonstrate the importance of chemical similarities between seed particles and the working fluids used when CPCs are characterized. We anticipate our study to contribute to a deeper understanding of chemical interactions during heterogeneous nucleation processes.

Counting on Chemistry: Laboratory Evaluation of Seed Material-Dependent Detection Efficiencies of Ultrafine Condensation Particle Counters

Condensation Particle Counters (CPCs) are crucial instruments for detecting sub-10 nm aerosol particles. Understanding the detection performance of a CPC requires thorough characterization under well-controlled laboratory conditions. Besides the size of the seed particles, chemical interactions between the working fluid and the seed particles also influence the activation efficiencies. However, common seed particle materials used for CPC characterizations are not chosen in respect of chemical interactions with 5 vapor molecules of the working fluid by default. Here, we present experiments on the influence of the seed particle material on the detection efficiencies and the 50 % cut-off diameters of commonly used CPCs for the detection of sub-10 nm particles. A remarkable set consisting of six different and commercially available particle detectors, including the newly-developed TSI V-WCPC 3789 and a tuned TSI 3776, was tested. The corresponding working fluids of the instruments are n-butanol, diethylene glycol and water. Among other materials we were able to measure detection efficiencies with 10 nanometer-sized organic seed particles reproducibly generated by oxidation of β-caryophyllene vapor in a flow tube. Theoretical simulations of supersaturation profiles in the condensers were successfully related to measured detection efficiencies. Our results demonstrate the importance of chemical similarities between seed particles and the used working fluids when CPCs are characterized. We anticipate our study to contribute to a deeper understanding of chemical interactions during heterogeneous nucleation processes.