Poly Methylphenylsiloxane Research Articles

High-resolution performance of pillar[6]arene functionalized with imidazolium ionic liquids for gas chromatography

Pillar[n]arenes (P[n]A, n = 5–10) have attracted much attention because of their highly symmetric pillar-shaped architecture with π-electron rich cavity. Nevertheless, the use of ionic liquid functionalized P[n]A in chromatography has not been reported up to data. This work reports the investigation of the imidazolium ionic liquids functionalized pillar[6]arene (P6A-C10-IM-C8[NTf2]) as the stationary phase for gas chromatography (GC). The statically coated P6A-C10-IM-C8[NTf2] column (0.25 mm i.d.) showed moderate polarity and high column efficiency of 4733 plates/m determined by n-dodecane at 120 °C (k = 2.29). Owing to its unique amphiphilic conformation, the P6A-C10-IM-C8[NTf2] showed good column inertness and resolving capability for a wide range of analytes and isomers. Particularly, the P6A-C10-IM-C8[NTf2] column exhibited distinctly advantageous performance for the challenging isomers of halogenated benzenes, benzaldehydes, phenols and anilines over the common commercial columns, namely 5% phenyl methyl polysiloxane (HP-5) and 35% phenyl methyl polysiloxane (HP-35). In addition, it exhibited good column repeatability and reproducibility with RSD values on the retention times less than 0.05% for run-to-run, 0.38% for day-to-day and 2.94% for column-to-column, respectively. This work demonstrates the promising future of ionic liquid P[n]A stationary phases for chromatographic separations.

Effect of phenyl side groups on the dielectric properties and dielectric behavior of polysiloxane

Over the past decades, polysiloxane-based dielectric elastomers (DEs) have attracted significant research attention; however, the low dielectric constant and poor breakdown strength of polysiloxane limit its application in DEs. In this study, the effect of phenyl side groups on the dielectric properties and unique dielectric relaxation behavior of polymethyl phenyl siloxane (PMPS) was investigated. The dielectric constant of PMPS was slightly improved from 3.45 to 3.60 by introducing appropriate amount of the phenyl side groups into polysiloxane. Moreover, the electrical breakdown strength of PMPS increased from 31.70 to 35.91 kV mm−1. The contribution of the α- and β-relaxations significantly increased the dielectric loss of PMPS. To better understand the effect of the phenyl side groups on these properties, the dielectric relaxation behavior of copolymers with different phenyl contents was studied in detail via broadband dielectric spectroscopy and thermally stimulated depolarization current measurements. This study paves a new path to design and prepare polysiloxane-based soft materials with high dielectric constant and improved electrical breakdown strength.

Kinetics of plasma-assisted chemical vapor deposition combined with inductively excited RF discharge and properties of a-C:H:SiOx coatings

The paper studies the plasma-assisted chemical vapor deposition of a-C:H:SiOx coatings in plasma of non-self-sustained arc discharge with a hot cathode combined with inductively excited radio-frequency (RF) discharge. The a-C:H:SiOx coatings are produced by polyphenyl methylsiloxane (PPMS) dissociation in plasma with and without RF discharge. The optical emission spectroscopy is used to study the PPMS dissociation process. Raman spectroscopy provides the structural investigations of the obtained coatings, while the energy dispersive X-ray spectroscopy is used to analyze the chemical composition. It is shown that the mechanical and tribological properties of a-C:H:SiOx coatings depend on the RF discharge power and the bias voltage amplitude of the substrate. It is demonstrated that substrate bias voltage can be reduced during the coating deposition in combined discharge without significant degradation of its mechanical and tribological properties due to the better dissociation and ionization of PPMS vapor molecules in inductively excited RF discharge.

Repair compositions based on methyl methacrylate modified with polyphenylsiloxane resin for concrete and reinforced concrete structures

In this paper, we consider the development of repair compositions for concrete and reinforced concrete structures based on methyl methacrylate modified with polymethyl phenyl siloxane resin. The condition has been studied and the problem analyzed in the country and abroad, as well as the selection of components for the repair composition. As a binder, methyl methacrylate curable with benzoyl peroxide in the presence of a catalyst - dimethylaniline and a modifier - polymethylphenylsiloxane resin would be used. The filler was finely ground quartz sand. The operational and physicomechanical properties of the resulting compositions were studied: photoabsorption, compressive strength, and tensile strength. Experimentally, the optimal ratio of polymethylphenylsiloxane resin in the composition was found to be 2.5 mass. parts of the modifier per 100 mass. parts including a binder. It was found that the introduction of polymethylphenylsiloxane resin does not significantly affect the adhesion characteristics, the tensile strength is reduced to a small extent. Moreover, the water absorption of the cured composition with a modifier content of 3 mass. parts compared with unmodified resin is reduced four times).

Understanding the effect of the fishbone-shaped networks on damping, thermal, and hydrophobicity properties

Based on an allyl-based epoxy resin (DADGEBA), a series of fishbone-shaped polymers were deliberately designed by reacting with hydride terminated methyl phenyl polysiloxane. The GPC, FTIR, and 1H NMR spectra confirmed that their structures can be tuned by the molar ratio between polysiloxane and epoxy. Results indicated that the proportion of fishbone networks has a profound effect on curing behavior, thermal, damping, surface and mechanical properties. Especially, when the fishbone networks become dominant in the networks, the introduction of flexible polysiloxane part will not decrease the intense internal friction due to the anchor sites. That is, the values of tan δ (max) exhibit as a characterization constant. Furthermore, the cured XEP-80 presents the widest transition range spanning over 150 °C with a peak half-width of 69 °C. These results are promising in the epoxy/polysiloxane industry to guide the synthesis of low-temperature damping adhesive for engineering application.

Plasma-Chemical Deposition of Anti-Reflection and Protective Coating for Infrared Optics

The films of amorphous hydrogenated carbon doped with Si and O were deposited onto the sample of crystalline silicon by method of plasma-chemical deposition in the mix of polyphenyl methylsiloxane vapors and argon. Physico-mechanical and optical properties of films were examined for their use as anti-reflection and protective coatings in infrared optics devices. Film transparency in the wavelength range of 2.5–8 μm was measured by method of infrared spectroscopy with a Fourier transform. The structure and composition of films were studied by methods of Raman and X-ray photoelectron spectroscopy. Hardness and other mechanical properties of films were determined by nanoindentation. It was shown that the double-sided deposition of a-C:H:SiOx films onto Si plates allows increasing their integrated transmission in the wavelength region of 3– 5 μm from 50 to 87%. The films possess excellent mechanical characteristics, thermal stability in the temperature range from room temperature to 500°С, and resistance to aqueous solutions of salt.

Determination of diethylenetriamine in workplace air by solvent desorption-gas chromatography

To establish solvent desorption gas chromatograph method for diethylenetriamine determination in workplace air. Diethylenetriamine in workplace air was collected with alkaline silicone tube, and desorbed with 0. 2 mol/L methanol solution of hydrochloric acid. After centrifugation, the supernatant neutralized with 0. 3 mol/L methanol solution of potassium hydroxide, was separated with 5%-phenyl-methyl polysiloxane(HP-5)(25 m×0. 32 mm×0. 52 mm)and measured with flame ionization detector. Detection limit of the method was 0. 49 μg/mL, quantification limit of the method was 1. 64 μg/mL, quantitative determination range of method was 1. 64-233. 80 μg/mL, and the minimum quantitative determination concentration was 0. 22 mg/m~3(based on 7. 5 L sample). The method had a good reproducibility, the relative standard deviation was 1. 4%-3. 3%, the average of desorption efficiency was 90. 8%, and the average of sampling efficiency was 93. 2%. The penetrating capacity of 200 mg alkaline silicone was over than 7. 1 mg, and the samples at room temperature could be preserved for 15 days at least. Ethylenediamine, triethylenetetramine or tetraethylenepentamine coexisted in the air did not interfere during the determination of diethylenetriamine. The method with low determination concentration, high accuracy and precision, is feasible for determination of diethylenetriamine in workplace air.

Plasma Chemical Synthesis of Amorphous Hydrocarbon Films Alloyed by Silicon, Oxygen and Nitrogen

The paper presents the synthesis of amorphous hydrocarbon (a-C:H) films alloyed by silicon, oxygen and nitrogen. The films obtained in polyphenyl methylsiloxane vapor and argon/nitrogen environment are deposited onto crystalline silicon surface using plasma chemical deposition. It is shown that the physical and mechanical properties of the films depend on the nitrogen concentration. The film composition is studied by Xray fluorescence spectrometry and Fourier-transform infrared spectroscopy. Raman spectroscopy is used to explore the film structure. A nanoindenter is used for testing the indentation hardness and other mechanical parameters of the films. It is shown that the chemical composition and properties of a-C:H:SiOx:N film can be maintained by changing the partial nitrogen pressure during the film deposition. The increase in the nitrogen content in a-C:H:SiOx:N film leads to the growth in the root mean square roughness and the contact angle. It also leads to the reduction in the carbon content and the film hardness caused by the lower content of sp3 carbon phase.

Separation of crocetane and phytane and measurement of their compound-specific carbon isotopic compositions

Crocetane and phytane are two isoprenoids isomers with similar molecular structures and often present together in methane-seep sediments and some Palaeozoic crude oils. Their commonly co-elution on gas chromatography is challenging for quality and quantity analysis, making it impossible to determine their compound-specific isotopic composition, and thus, insight their geological and geochemical significance. A new gas chromatography method is reported here using a DB-17MS column (50%-phenyl-methyl polysiloxane as the stationary phase) that successfully achieved baseline separation of crocetane and phytane and can be used to accurately identify and quantify them on gas chromatography and gas chromatography–mass spectrometry. Routine steroids and terpenoids biomarkers can also be analysed simultaneously. Additionally, their compound-specific carbon isotopic compositions were also measured without matrix influence using this method. This is the first time that a simple chromatographic method for direct determination of compound-specific carbon isotopic composition of crocetane has been reported publicly.

Amphiphilic triptycene-based stationary phase for high-resolution gas chromatographic separations

This work reports a new type of triptycene-based amphiphilic stationary phase (TP-2IL) for gas chromatography (GC). It is an integration of the 3D π-rich triptycene framework with ionic liquids. Its capillary column showed the efficiency of 3880 plates/m determined by n-dodecane at 120 °C (k = 2.79) and exhibited good performance for analytes from apolar to polar nature. Particularly, it has outstanding capability for resolving critical pairs of anilines and phenols with good peak shapes and shows distinct advantages over its composing counterparts (TP-2BO and O-IL) and widely-used commercial columns, namely 35% phenyl methyl polysiloxane (DB-35) and polyethylene glycol (INNOWAX). Moreover, the TP-2IL column exhibited good repeatability and reproducibility with the values of relative standard deviation in the range of 0.02%–0.07% for run-to-run, 0.10%–0.35% for day-to-day and 2.9%–5.1% for column-to-column, respectively, and good thermal stability up to 300 °C. Furthermore, its applications for determining isomer impurities in real samples demonstrate its feasibility for practical GC analysis. This work presents a facile strategy for constructing triptycene-based stationary phases with amphiphilic selectivity and provides alternatives of highly selective stationary phases for chromatographic analysis.

Phytochemical screening of Leucaena leucocephala leaf essential oil and its antibacterial potentials

Objective: The study aimed to identify the phytochemical composition of Leucaena leococephala leaf and evaluate the antimicrobial potential of the essential oil from the leaf. Material and Methods: The sample was subjected to Clevenger apparatus to extract the oil. The essential oil was characterized by chromatography method (GC-MS). The GC-MS was performed on Perkin Elmer gas chromatography model Clarus 680 equipped with HP-5 fused capillary column (5%) phenylmethyl polysiloxane stationary phase with 30m length, 0.25µm of film thickness and 0.25oc and 280oc respectively. Antibacterial activity using Agar Disc Method. Result: The result obtained from the GC-MS presented thirty phytochemicals of which Neophytadiene (9.48%), Octadecane (3.15%), 1-Octadecyne (3.85%), Phytol (52.51%) and Hexacosane (7.26%) are major. The antibacterial potential activities were observed in various ways with zone of inhibition diameters ranging from 0.70±0.00mm to1.27±0.06mm for staphylococcus aureus and Klebsielia pneumonia respectively among the six-concentration selected (25, 50, 100, 250, 500, and 1000ppm). Conclusion: It is investigated in this present studies that Leucaena leococephala essential oil can be utilized against the management of antibacterial diseases particularly Klebsielia pneumonia and Staphylococcus aureusas well as used in the Pharmaceutical and Cosmetics industry.

Nickel-containing hybrid ceramics derived from polysiloxanes with hierarchical porosity for CO2 methanation

Abstract Nickel-containing hybrid ceramics were prepared by pyrolytic conversion from either methyl or methyl-phenyl polysiloxanes mixed with bistrimethoxysilylpropylamine (BisA) as a complexing agent and nickel salt. Materials with tailorable characteristics were generated by varying the pyrolysis temperature from 400 up to 600 °C in order to evaluate their applicability in the CO2 methanation. The materials were characterized by thermogravimetric analysis (TGA), N2 adsorption-desorption isotherms (BET-BJH), water and n-heptane adsorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM). In-situ X-ray diffraction analysis (in-situ XRD) was used to evaluate the Ni particle structure and size during a simulated catalytic reaction. Porous hybrid ceramics (ceramers) with high specific surface areas (100–550 m2 g−1), hydrophobic or hydrophilic surfaces and different Ni particle sizes (4–7 nm) were obtained by varying the pyrolysis temperature and polysiloxane composition. The pyrolytic conversion of polysiloxanes combined with the complexing amino-siloxane BisA not only permitted a good dispersion of the Ni nanoparticles but also enabled the formation of hierarchical porosity with micro-, meso- and macropores. Regarding the catalytic performance, ceramers prepared from methyl polysiloxane exhibited a more hydrophobic surface and improved catalytic performance compared to the ones prepared from methyl-phenyl polysiloxane. A negative effect on the catalytic performance of ceramers was observed with increasing pyrolysis temperatures, which led to an increase in Ni particle size (from 4 to 7 nm), and lower levels of conversion and selectivity. The ceramers pyrolyzed at 400 °C exhibited the best catalytic performance, showing selectivity up to ∼77% and good stability over a 10 h test, during which the Ni particle size was preserved.

High-resolution turbulent flow chromatography

The resolution power of turbulent flow chromatography using carbon dioxide as the mobile phase and coated (crosslinked methyl phenyl polysiloxane) open tube columns (OTCs) as the stationary phase was investigated under retentive conditions (0 <k< 1). The improvement in column efficiency from a laminar to a turbulent flow regime was accurately measured for small molecules (coronene and benzo[a]anthracene). This relative increase in column performance decreased from 9 to 5, 3, and to 3 with increasing the retention factor from 0 to 0.2, 0.5, and to 1.0, respectively. Despite a four to five orders of magnitude larger sample dispersion coefficient in turbulent than in laminar flow, the mass transfer in turbulent flow chromatography is still controlled and limited by the slow sample transport across the viscous layer at the column wall. The benefit of turbulent flow chromatography is then restricted to small retention factor (k< 0.2). From a practical viewpoint, turbulent flow chromatography using carbon dioxide as the mobile phase and 20 m long × 180 μm i.d. × 0.2 μm film thickness OTCs provides ultra-fast (analysis time < 10 s) and high-resolution (plate counts of 33,000) separations of weakly retained compounds (k∼0.1) at Reynolds number around 5000 (3.75 mL/min, 3000 psi back pressure).

A Newly Designed Dual‐Functional Epoxy Monomer for Preparation of Fishbone‐Shaped Heterochain Polymer with a High Damping Property at Low Temperature

A novel high purity dual‐functional epoxy monomer, diglycidyl ether of 4,4′‐diallyl‐bisphenol‐A, is deliberately designed for the construction of a fishbone‐shaped heterochain polymer by polymerizing it with the methyl phenyl polysiloxane. Their curing reactions with Jeffamine D230 are investigated. The cured fishbone‐shaped heterochain polymer presents a wide transition range spanning over 120 °C with a peak half‐width of 62 °C. In contrast to the traditional epoxy/polysiloxane materials, the cured fishbone‐shaped heterochain polymer takes full advantage of the cooperative effect of epoxy and polysiloxane exhibiting excellent damping properties (tan δ &gt; 0.3) at temperatures near the T g of the polysiloxane. This outstanding low‐temperature damping performance can be ascribed to the fishbone‐shaped structure of the heterochain polymer. These results provide new approach to explore high damping materials used at extremely low temperature (−125 °C). image

Mechanoluminescence excited by hypervelocity impact of a projectile on a target coated with ZnS:Mn phosphor

When a small aluminium projectile moving with a velocity of several km/s makes an impact on to an aluminium target whose opposite side is coated with ZnS:Mn phosohor using polyphenyl methyl siloxane (PPMS) binder, then initially the ML intensity increases with time, attains a peak value Im, at a particular time tm, and later on it decreases with time. The value of peak ML intensity increases with the increasing impact velocity of the projectile. For a high piezoelectric field on to the ZnS:Mn phosphor, the bending of bands takes place, and the trapped electrons tunnel to the conduction band, and subsequently, the energy released during the electron–hole recombination and the electron capture in vacant deep traps excites the Mn2+ ions and de-excitation gives rise to the light emission characteristic of the Mn2+ ions. Expressions are derived for different characteristics of ML, in which a good agreement is found between the experimental and mathematical results. Using impact-induced ML the lifetime of excited Mn2+ ions, lifetime of electrons in the shallow traps, and decay time of impact pressure can be determined. Using the calibrated curve between the ML intensity and impact velocity of the projectile, the unknown impact velocity of the projectile can be determined, and thus, the ML can be used as an impact sensor. With increasing impact velocity of the projectile the kinetic energy of the projectile increases. In this case, the expressions suggest that, both the peak ML intensity and total ML intensity should increase with increasing energy of the projectile. From the ML intensity versus time curve, the pressure versus time curve can be obtained as follows: (i) Normalizing the peak ML intensity as maximum impact pressure, and (ii) after tm, replacing the decay of ML intensity by the decay of pressure. It is to be noted that the pressure versus time curve plays important role in applied mechanics. Micrometeoroid and ultra high speed (hypervelocity) debris impacts pose a significant threat to spacecraft. As the mechanoluminescence has the potential to be used to detect impacts and other phenomena, it can be used as the active element for an impact detection system for spacecraft or bases on the Moon or other places. Thus, further studies on the ML at high impact velocities are required. The study of ML at hypervelocity of impact may also be helpful to understand the earthquake lights, pre-earthquake phenomena, post-earthquake phenomena, etc.

Evolution of properties in composite carbon films under thermal conditions and in the presence of a catalyst

The characteristics of composite carbon films are experimentally studied. The films are synthesized under concurrent conditions of the magnetron and plasmatron sputtering of molybdenum disilicide and polyphenyl methylsiloxane (PPMS 2/5). Automodulation of the elemental and phase composition is found and studied in the direction of film deposition onto the substrate. The stability of the automodulation parameters to subsequent high-temperature annealing is examined.

Manufacturing and characterization of polyether ether ketone/methyl phenyl polysiloxane composite coatings

ABSTRACTIn this work, manufacturing and characterization of single‐ and multilayer polyether ether ketone (PEEK)‐reinforced coatings were investigated. Hybrid composites of thermoplastic reinforcing agents in a thermoset resin was, therefore, achieved by dispersing large PEEK particles (∼85 μm diameter) in methyl phenyl polysiloxane (MPP). First, mechanism of formation of the polymeric networks during MPP curing at different temperatures (250–400 °C) was analyzed. The different arrangements of the PEEK powders inside the cross‐linked network of the MPP resin were, thus, disclosed. Second, the effect of process parameters on visual appearance, morphological features, and mechanical response of the composite coatings was evaluated by contact gauge profilometry, scanning electron microscopy, IR spectrometry, and microscratch indentations. Moderate temperature curing (250 °C &gt; T &gt; 300 °C) of the composite coatings led to polysiloxane resins harder, well adhered on the metal and able to retain better the PEEK reinforce. Further increase in curing temperature (350 and 400 °C) might embrittle the polysiloxane resin, with the PEEK powders in it partially attenuating the loss of properties of the composite coating. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43609.

A potential base substrate for deformable scintillation materials

Deformable scintillation materials for radiation detection are an original concept that will impact many applications. Here we reveal the optical characteristics of readily available, transparent grease that consists of adhesive aromatic ring polymers. The aromatic ring polymer is methyl phenyl polysiloxane, commonly used in cosmetics, lubrication, heat conduction, and mechanical damping. It has a 285-nm excitation maximum and emits short wavelength light that peaks at 315nm. The stopping power for 1MeV electrons is 1.78MeVcm2/g. The light-yield distribution has distinct peaks at 976keV from internal conversion electrons and at 5486keV from alpha particles. In addition, this particular methyl phenyl polysiloxane is safe for use and disposal, which is an excellent advantage. These aromatic ring polymers are potential base substrates for deformable scintillation materials and make an important addition to the categories of scintillation materials.

The Deposition of Silicon-Carbon Coatings in Plasma Based Nonself-Sustained Arc Discharge with Heated Cathode

Silicon-carbon coatings on silicon substrates were deposited in plasma based nonself-sustained arc discharge with heated cathode by plasma polymerization of silicon organic agent such as polyphenyl methylsiloxane (PPhMS). Silicon-carbon coatings were deposited at PPhMS flow rate of 0.012 ml/min, argon pressure of 0-0.1 Pa, discharge current of 5-8 A, discharge voltage of 130-150 V, and filament current of 68 A. Bipolar pulsed bias voltage was supplied on the substrate during coating deposition. Surface morphology, hardness and elastic modulus of silicon-carbon films were investigated after the deposition. The film surface is very smooth with root-mean-square roughness of 0.579 nm. Maximum hardness of coatings was 11 GPa, and maximum elastic modulus was 142 GPa.

Surfactant assisted syntheses of monolithic hybrid ceramics with hierarchical porosity

A surfactant assisted emulsion-based syntheses route is presented for obtaining organo-silica-based monolithic hybrid ceramics with a hierarchical pore size distribution and tailorable surface characteristics. Methyl polysiloxane (MK) and methyl-phenyl polysiloxane (H44) with varying mixing ratios are selected as precursors, cross-linked and subsequently pyrolyzed at 500°C or 600°C, respectively. By adjusting the oil/water ratio and by tailoring the surfactant concentration controlled micro and macropore distributions with mesoscopic cell windows are obtained. After pyrolysis, specific surface areas of up to 600m2/g are achieved. In addition, due to the distinguished pyrolysis decomposition behavior of MK and H44, the adjustment of the surface characteristics in terms of hydrophobicity or hydrophilicity is demonstrated. The presented surfactant assisted emulsion-based process is hence highly suitable for tailoring pore size distribution and surface characteristics at the same time. Both material properties are pivotal features for catalysis and gas separation applications.