Poly Methyl Hydrogen Siloxane Research Articles

Preparation of SiO2 nanoparticles with adjustable size for fabrication of SiO2/PMHS ORMOSIL superhydrophobic surface on cellulose-based substrates

Silica (SiO2) nanoparticles with controlled particle size and poly(methylhydrogen)siloxane (PMHS) were applied to fabricate superhydrophobic SiO2/PMHS ORMOSIL (organically modified silicate) coating on cellulose-based substrates (wood, cotton and filter paper). The influence of weight ratio of ammonia to TEOS, H2O to TEOS and ethanol to TEOS on the particle size of SiO2 nanoparticles was evaluated by the response surface methodology. The results indicated that the particle size of SiO2 nanoparticles could be well-controlled between 25 nm and 100 nm. The effect of particle size on hydrophobicity of SiO2/PMHS ORMOSIL coated wood was investigated. The modified wood had the best hydrophobicity as the particle size of SiO2 was 75 nm, possessing a water contact angle of 158.2°. After deposition of SiO2/PMHS ORMOSIL coating, the water resistance and anti-fouling property of wood increased obviously. The water absorption decreased significantly from 70.3% to 24.1%. In addition, SiO2/PMHS ORMOSIL was further applied to functionalize filter paper and cotton for oil/water separation. The separation efficiency of diesel from water was 96%–99% for modified filter paper after separation for 20 cycles, while the absorption capacity was 10.5 times of the modified cotton.

Tribological and Wetting Properties of TiO2 Based Hydrophobic Coatings for Ceramics

Hydrophobic and self-cleaning photocatalytic ceramics and concrete with potential for the superhydrophobicity are promising novel materials for civil engineering applications including buildings, bridges, road pavements, and airport runways. Due to embedded liquid-repellent properties, such materials have low water and salt absorption and, therefore, enhanced durability. However, in applications requiring high traction (e.g., tire and pavement), there is a concern that reduced adhesion may compromise the friction. This paper reports on wetting, dry friction, and roughness properties of TiO2 coated (hydrophilic) and polymethyl hydrogen siloxane (PMHS) coated (hydrophobic) self-cleaning ceramic tiles. The coefficient of friction values of the tile–rubber interface do not change significantly with the applications of the coatings up to 0.67 for hydrophilic TiO2 based and up to 0.46 for hydrophobic TiO2 + PMHS coatings versus 0.45 for uncoated reference. Friction has adhesion and roughness-related components and this response can be attributed to the roughness component of friction due to TiO2 coating. The challenges related to hydrophobic coatings, including the durability and future research, are also discussed.

An Effective, Economical and Ultra-Fast Method for Hydrophobic Modification of NCC Using Poly(Methylhydrogen)Siloxane.

Poor compatibility between nanocellulose crystals (NCCs) and major polymers has limited the application of NCC as bio-reinforcements. In this work, an effective and ultra-fast method was investigated to significantly improve the hydrophobicity of NCC by using poly(methylhydrogen)siloxane (PMHS) as modifier. PMHS possessed amounts of reactive –Si–H groups and hydrophobic –CH3 groups. The former groups were reactive with the hydroxyl groups of NCC, while the latter groups afforded NCC very low surface energy. As the weight ratio of PMHS to NCC was only 0.0005%, the hydrophobicity of NCC was significantly improved by increasing the water contact angle of NCC from 0° to 134°. The effect of weight ratio of PMHS to NCC and the hydrogen content of –Si–H in PMHS on the hydrophobicity and thermal stability was investigated in detail by Fourier transform infrared spectroscopy (FTIR), (X-ray Diffraction) XRD and (thermogravimetric analysis) TGA. The results indicated that PMHS chains were covalently grafted onto NCC and PMHS modification improved the thermal stability of NCC.

Fabrication of Hydrophobic ZnO/PMHS Coatings on Bamboo Surfaces: The Synergistic Effect of ZnO and PMHS on Anti-Mildew Properties

Poor mildew resistance has limited the application of bamboo materials. In this work, ZnO/PMHS coatings were fabricated on bamboo timber surfaces by hydrothermal synthesis method and hydrophobic modification with poly(methylhydrogen)siloxane (PMHS). The surface chemical characteristics and microstructure of the bamboo before and after modification were investigated using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and water contact angle (WCA). The morphology results indicated that ZnO on the surface of bamboo forms flower-like aggregations. The WCA of ZnO/bamboo increased from 65° to 142° after PMHS hydrophobic modification, indicating that the hydrophobicity of bamboo was significantly improved. The original bamboo had poor anti-mildew properties when exposed to Trichoderma viride, Aspergillus niger, and Penicillium citrinum. After depositing ZnO onto the surface of the bamboo, the anti-mildew properties were significantly improved. Furthermore, it was found that after PMHS hydrophobic modification, ZnO/bamboo had excellent anti-mildew properties when exposed to the three mold hyphae, which indicated that PMHS hydrophobic modification had a synergistic effect on the anti-mildew properties of bamboo with a ZnO coating.

Modified silicone oil types, mechanical properties and applications

Silicone oil is famous for its greater stability and high-temperature non-toxic use at low surface tension and high spreading power. It is the mixture of polydimethylsiloxanes (PDMS) with dimethicone and simethicone, therefore largely used in industrial products due to their unique properties like non-toxicity, high lubricity and stable film strips formations, and widely used in lubricants, electric insulator, laboratories, anti-foaming, etc. Silicone oil is chosen by improving their lubrication performance in mechanical system like resin, films, satellite and space vehicles. The purpose of this study is to design for evaluating and distinguishing feature of polydimethylsiloxane (PDMS) or silicone oil to show their mechanical and thermal properties. In industrial field, i.e., improved their adhesive and contact angle properties for their long time durability and stability. The aim of this review is to elaborate and distinguish the feature of polydimethyl siloxane (PDMS) or silicone oil to show their mechanical and thermal properties showing the shinning properties and importance of silicone oil in daily routine and in industry. Also silicone oil and there derivates like polymethyl hydrogen siloxane, amino silicone, phenyl methyl silicone, vinyl silicone and hydrogen silicone oil play a key role in curing agent, hair-care cosmetics and shampoos and thermostat fluid anti-adhesion processing. Materials which we have used in this review such as polymethyl hydrogen siloxane, amino silicone oil, phenyl methyl silicone oil, vinyl silicone oil and hydrogen silicone oil show significant and potential properties in various fields of industries. Different types of methods like cross-linking, copolymerization and coupling agents were used in different reactions in this review. Also synthetic types of compounds were also used for different properties giving excellent results. This review highlighted the beneficial aspects of silicone oil in various fields. Silicone oil shows prominent properties like lubrication, smooth gliding behavior, wettability, mechanical strength, mechanical stability and high-performance coating. Silicone oil is also useful for decreasing surface tension and retaining the moisture.

Preparation of hydrophobic broadband antireflective SiO2 coating on flexible poly(methyl methacrylate) substrates

The double-layer broadband antireflective coatings is crucial for optical devices, e.g. plastic eyeglass lenses and the solar cell system. Among optical situation, the wide wavelength range of light is one of the most demanded. Here we designed a double-layer broadband antireflective (AR) coating with excellent average transmittance at visible region for poly (methyl methacrylate) (PMMA) using thin film design software. A template-free sol–gel process was developed to prepare the SiO2/PMHS coating with ultralow refractive index of 1.13 for top layer. By combining the colloidal silica and poly (methyl hydrogen) siloxane (PMHS), the coating with adjustable refractive index that vary between 1.13 and 1.37 was obtained. The formation mechanism of the ultralow refractive index was proposed. Meanwhile, using PMHS to partially substitute the hydrophilic groups in the coating, the hydrophobicity of the coatings was improved, and its static water contact angle was as high as 126°. Besides, the coating had excellent mechanical property and refractive index of 1.22–1.42 can be well prepared by combining base-catalyzed silica sol and acid-catalyzed silica sol together for bottom layer. Then, using the two raw materials base/acid -catalyzed mix SiO2 sol and the PMHS-SiO2 sol and optimizing the thickness, the prepared double-layer coatings with average transmittance of 99.30% in the 400nm to 800nm wavelength on PMMA substrate was successfully obtained. Those prepared hydrophobic broadband AR coatings represented excellent transmittance and had enormous potential application in the optical devices.

Top Layer Coating for Improving Superhydrophobic Property of Latex Cup

A latex cup is used to collect latex from a rubber tree which is an economic plant in Thailand. The fresh latex or crude rubber consists of organic compound and water which can wet and adhere to surface of the collecting cup. In this research, surface of the latex cup was treated with polymethylhydrogen siloxane-functionalized silica compound to improve hydrophobicity so that it could repel the dirt and latex, resulting in an anti-adhesion between the latex and the cup. Surface of the latex cup was etched with 10 % v/v hydrofluoric acid for 30 min before application of the siloxane coating which was performed by immersion in the solution, painting and spraying, respectively. The result revealed that the immersion method exhibited optimum property justified by high value of water contact angle, low surface free energy, surface roughness and the field test. At the optimum polymethylhydrogen siloxane : fumed silica ratio of 3 : 1 wt%, the treated sample had water contact angle of 139.24 ± 0.78 degrees and possessed surface energy of 1.07 mJ/m2. The field test conducted in the rubber field in Trang province revealed good durability of the coating. The water contact angles were 132.15 ± 2.05 and 129.20 ± 2.34 degrees after 2 weeks and 1 month, respectively, of the field service.

Sol-gel preparation of antireflective coatings with abrasion resistance by base/acid double catalysis and surface treatment

The Antireflective coatings (ARCs) dip-coated in base catalyzed sol have been demonstrated excellent optical property for its high porosity. However, its poor abrasion-resistance limits the industrial promotion. In this paper, the porous silica ARCs with excellent optical properties and abrasion-resistance were prepared by base/acid double catalysis. At the beginning of spherical SiO2 particles growing process, the tetraethoxysilane (TEOS) sol-gel environment was basic as the function of ammonia catalyst. After a period of time, the environment was changed to acid by using hydrochloric acid as catalyst, substituting for ammonia. The sol prepared by this method shows excellent stability. When the aging time increased from 30 days to 180 days, the refractive index only increased 0.024. Compared with the films dip-coated in the base silica sol, the porosity was lower and the particles’ agglomeration was more obvious. Besides, the coated glasses also possess better optical property and abrasion-resistance. The peak transmittance of the samples increased from 98.6% to 98.9%, while the pencil hardness grade also increased from <6B to 2B degree. The cotton scrubbing test also proved the improvement of abrasion-resistance. The poly (methylhydrogen) siloxane (PMHS) surface treatment was proved to be a great assistant for the base/acid double catalysis process. After the treatment, the pencil hardness grade could further increase to 5H, while the peak transmittance only decreased 0.3%.

One-step sol-gel preparation of hydrophobic antireflective SiO2 coating on poly(methyl methacrylate) substrate

A hydrophobic nanoporous antireflective (AR) SiO2 coating was deposited on poly(methyl methacrylate) (PMMA) substrate by sol-gel process. The average transmittance of PMMA substrate with designed SiO2 coating in the region of 400–1100nm was higher around 6.3% than that of substrates (92.0%). It was noted that a maximum transmittance of 99.9% was achieved at the wavelength of 550nm. The poly(methyl hydrogen) siloxane (PMHS) was introduced to replace the hydroxyl (OH) groups and decrease the surface energy of the coating, it increased significantly the hydrophobicity. Consequently, static water contact angle as high as 125.0±1° was obtained. Cross sectional SEM showed that conformal coating was achieved on PMMA substrate. The hydrophobic AR SiO2 coating exhibited excellent performance on PMMA substrate, showing great application potential in optical devices.

Refractive-tunable and hydrophobic antireflective coatings by PMHS-modification assisted sol–gel method

By a poly(methylhydrogen)siloxane (PMHS) modification assisted sol-gel method, refractive-tunable antireflective coatings (ARCs) were successfully prepared. The refractive indices of ARCs could be conveniently adjusted from 1.23 to 1.36. The water contact angle increased significantly from 27° to 128° after PMHS modification, which afforded ARCs better antireflective stability. After being kept in a closed container for 1 month with 95% relatively humidity at room temperature, the transmittance of unmodified and PMHS modified ARCs decreased by 1.6% and 0.2%, respectively.

Properties of a novel polysiloxane-guttapercha calcium silicate-bioglass-containing root canal sealer

ObjectiveRoot canal filling sealers based on polymethyl hydrogensiloxane or polymethyl hydrogensiloxane-guttapercha – introduced to improve the quality of conventional guttapercha-based and resin-based systems – showed advantages in handiness and clinical application.The aim of the study was to evaluate the chemical–physical properties of a novel polysiloxane-guttapercha calcium silicate-containing root canal sealer (GuttaFlow bioseal). MethodsGuttaFlow bioseal was examined and compared with GuttaFlow2, RoekoSeal and MTA Fillapex sealers. Setting times, open and impervious porosity and apparent porosity, water sorption, weight loss, calcium release, and alkalinizing activity were evaluated. ESEM-EDX-Raman analyses of fresh materials and after soaking in simulated body fluid were also performed. ResultsMarked differences were obtained among the materials.GuttaFlow bioseal showed low solubility and porosity, high water sorption, moderate calcium release and good alkalinizing activity. MTA Fillapex showed the highest calcium release, alkalinizing activity and solubility, RoekoSeal the lowest calcium release, no alkalinizing activity, very low solubility and water sorption. Only GuttaFlow bioseal showed apatite forming ability. SignificanceGuttaFlow bioseal showed alkalinizing activity together with negligible solubility and slight calcium release. Therefore, the notable nucleation of apatite and apatite precursors can be related to the co-operation of CaSi particles (SiOH groups) with polysiloxane (SiOSi groups).The incorporation of a calcium silicate component into polydimethyl polymethylhydrogensiloxane guttapercha sealers may represent an attractive strategy to obtain a bioactive biointeractive flowable guttapercha sealer for moist/bleeding apices with bone defects in endodontic therapy.

Cholesteric Cyclohexane-Containing Side-Chain Liquid-Crystalline Polysiloxanes

Two new kinds of Cholesteric cyclohexane-Containing Side-Chain Liquid-Crystalline Polysiloxanes (PAand PB) were synthesized via hydrosilylation reaction of polymethyl hydrogen siloxane with cyclohexane mesogenic monomers (MAand MB). The yield of PA, PBwere 71.6%, 82.5% and 81.0%, respectively. The molecular structures of MAand MB, PAand PBwere investigated by Fourier transform infrared spectroscopy (FTIR) and hydrogen-nuclear magnetic resonance spectra (1H-NMR). The corresponding liquid crystalline phase type was also observed by polarizing optical microscopy (POM) and X-ray diffraction (XRD). The liquid crystalline phase behavior and thermal properties of the polymers were analyzed by differential scanning calorimetry (DSC). Results showed that MAand MBexhibited multicolor platelet texture of a blue phase and cholesteric phase, and the Tmand Tiof MAand MBincreased with the increasing flexible chain length. The mesophase temperature range of PAand PBwas broader than that of MAand MB. PAexhibited a rare nematic phase----spherulite texture of polymeric smectic A phase. PBwere of cholesteric and nematic---- cholesteric phase. The Tmand Tiof PAand PBincreased with the increasing flexible spacer groups.

Self-Assembling Particle-Siloxane Coatings for Superhydrophobic Concrete

We report here, for the first time in the literature, a method to synthesize hydrophobic and superhydrophobic concrete. Concrete is normally a hydrophilic material, which significantly reduces the durability of concrete structures and pavements. To synthesize water-repellent concrete, hydrophobic emulsions were fabricated and applied on portland cement mortar tiles. The emulsion was enriched with the polymethyl-hydrogen siloxane oil hydrophobic agent as well as metakaolin (MK) or silica fume (SF) to induce the microroughness and polyvinyl alcohol (PVA) fibers to create hierarchical surfaces. Various emulsion types were investigated by using different mixing procedures, and single- and double-layer hydrophobic coatings were applied. The emulsions and coatings were characterized with optical microscope and scanning electron microscope (SEM), and their wetting properties, including the water contact angle (CA) and roll-off angle, were measured. A theoretical model for coated and non-coated concrete, which can be generalized for other types of materials, was developed to predict the effect of surface roughness and composition on the CA. An optimized distance between the aggregates was found where the CA has the highest value. The maximal CA measured was 156° for the specimen with PVA fibers treated with MK based emulsion. Since water penetration is the main factor leading to concrete deterioration, hydrophobic water-repellent concretes have much longer durability then regular concretes and can have a broad range of applications in civil and materials engineering.

Ultra-fast surface hydrophobic modification of sol–gel silica antireflective coating with enhanced abrasion-resistance

A novel and ultra-fast route was proposed to modify the surface hydrophobicity of sol–gel silica antireflective (AR) coating with poly(methylhydrogen)siloxane (PMHS). The hydroxyl groups on silica particle are thought to react with the hydrogen atoms within several seconds at room temperature in the presence of platinum catalyst. The surface modification can be accomplished simply by immerging silica AR coating into the PMHS/hexane solution containing platinum catalyst and then withdrawing immediately from the solution. The hydrophobicity and abrasion-resistance of PMHS modified AR coating were significantly improved. This provides a new method for the preparation of abrasion-resistant sol–gel silica AR coating used in outdoor environment.

Ruthenium and Iron Carbonyl Clusters Catalyzed Reduction of N,N-dimethylbenzamide and N,N-diethyl&lt;i&gt;-&lt;/i&gt;(3-methyl)benzamide

One new Ruthenium and one known Iron bimetallic carbonyl clusters containing triphos (1,1,1-tris(diphenylphosphinomethyl)ethane) ligand have been prepared as catalyst to study the reduction of amide to amine. All clusters were characterized by elemental analysis, 1HNMR, 31PNMR and IR spectroscopy. The reduction of N,N-dimethylbenzamide and N,N-diethyl-(3-methyl) benzamide catalyzed by Ru and Fe carbonyl clusters were investigated at 100 ~ 110 °C for 24 ~ 28h, polymethylhydrogensiloxane (PMHS) as reduction agent. The products were analysized using GC-MS, IR and UV-vis spectroscopy and an excellent yield (97%) of N,N-diethyl- (3-methyl)benzamine was obtained when using 3 mol% of bimetallic ruthenium carbonyl cluster as catalyst. The data of IR and UV-vis show that the frameworks of clusters are not changed remarkably during the reaction.

Investigation of the Effects of Gas versus Liquid Deposition in an Aerosol‐Assisted Corona Deposition Process

AbstractThe particle size of polymethylhydrogen siloxane (PHMS) and hexamethyldisiloxane (HMDSO) droplets nebulised into an atmospheric pressure plasma was investigated using laser particle imaging. At low precursor flow rates the volatile HMDSO monomer is shown to be vapourised by the nebulisation process and no discrete aerosol droplets enter the plasma. This results in a standard gas phase PECVD process. As the precursor flow rate increases, liquid aerosol droplets are detected in the plasma. The diameter and number of droplets is largely unaffected by exposure to the plasma and intact droplets exit the plasma and impact directly on the substrate. The change in precursor flow is found to significantly alter the surface morphology of the deposited coatings with minimal impact upon the coating chemistry. magnified image

Chemical Resistant Improvement of Natural Rubber and Nitrile Gloves by Coating with Hydrophobic Film

In this paper, we report innovative gloves that are coated with hydrophobic film such that the outer surface of the gloves is hydrophobic. A coating precursor containing polymethyl hydrogensiloxane, silica nanoparticle, semifluorinated silane and Pt-catalyst was painted onto the gloves. The coated gloves were kept at room temperature for 12 h to make the film dry, and then tested for their chemical resistance with 10 M NaOH, conc. HCl, conc. H2SO4 and conc. HNO3 solutions, as well as the standard buffered solutions (pH = 1, 4, 10, and 12) at 25oC by dropping the chemicals onto the coated gloves. It was found that the nitrile gloves had similar contact angles to the latex gloves when tested with the standard buffered solutions while the nitrile gloves had higher contact angles compared to the latex gloves when tested with different aqueous-based hazardous chemicals. The nitrile gloves coated with the hydrophobic film showed high acid droplet contact angle, leaving behind much lesser damage from hazardous chemicals.

Polysiloxane Gel with Low Crosslinking Density for Make-up Cosmetics

Silicic anhydride has conventionally and routinely been used as a gelling agent for silicones. In the present study, the mechanism wherein a crosslinked silicone having a specific crosslinking density is swollen in the presence of a silicone oil having a low viscosity to form a stable gel was applied to the manufacture of foundations, and optimum conditions that provide favorable functions and satisfactory organoleptic sensation were studied. Polymethylhydrogen siloxanes with a low crosslinking density were prepared by subjecting α,ω-divinyl polydimethyl siloxane to addition polymerization. The viscoelasticities of the gels formed by the resultant products and silicone oil were investigated. based on these results, it is concluded that the most suitable product is a low crosslinking density material obtained by adding α,ω-divinyl polydimethyl siloxane (M¯w: 1.0 kDa) to polymethyl hydrogen siloxane having an average molecular weight of 2.5 kDa under the conditions wherein the concentration of dimethylpolysiloxane (viscosity: 6 × 106 m2 S-1) is 60%. This product provides an enhanced viscosity at a reduced solids content. © 1997 John Wiley & Sons, Ltd.

Effect of Palladium Coordination on Liquid Crystallinity of Imine Side Chain Polysiloxane

Abstract A new type of Pd-coordinating imine side chain liquid crystalline polysiloxane (Pd-ImLCP) has been synthesized by hydrolyzation reaction of N-(4-n-undecylenoxy-benzylidene)-4-dodecyloxyaniline with polymethylhydrogensiloxane (PMHS), then by ortho-palladation reaction of the obtained polymer ligand, imine side chain liquid crystalline polysiloxane (ImLCP), with various amounts of palladium acetate. The corresponding low molar mass Pd-coordinating imine complex (Pd-Im) has been also prepared for comparison. Their mesomorphic properties have been studied by polarizing microscopy, DSC and X-ray diffraction methods. The incorporation of Pd ions into the macromolecules ImLCP can affect the mesophase transitions in different ways. By increasing the molar percentage of Pd in the polymer, the textures turn from smectic to nematic phases and the transition temperatures almost stay constant up to 27 mole% and then decrease to 80 mole% at which crosslinking occurs. The clearing temperatures Tcl and enthalpy ...

ChemInform Abstract: A GENERAL ROUTE TO DIOXABICYCLO(N.2.1)ALKANES

AbstractAus den Cycloalkenen (I) erhält man über die Hydroperoxide (II) die Dibromide (III), die zu den cyclischen Bromperoxiden (IV) cyclisieren.