Deposition of HMDSO-based coatings on PET substrates using an atmospheric pressure dielectric barrier discharge

This paper presents results on the formation of coatings in an atmospheric pressure dielectric barrier discharge using hexamethyldisiloxane (HMDSO) as gaseous precursor. Plasma-polymerized films are deposited onto polyethylene terephthalate (PET) films using argon and argon/air mixtures as carrier gases. The chemical and physical properties of the obtained coatings are discussed in detail using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). FTIR and XPS results show that the composition of the gas phase and the chemical structure of the obtained coatings are clearly correlated. When pure argon is used as working gas, the film is polymeric with a structure close to [(CH₃)₂–Si–O]_n, which means that the deposited films resemble PDMS. However, if plasma-polymerization occurs in argon/air mixtures, the deposited film is silica-like containing only few carbon atoms. These dense SiO_x coatings generally exhibit high barrier properties, while pure HMDSO-derived films might be of importance for selective permeation. From this point of view, the capability of controlling the film composition by varying the operation conditions opens interesting perspectives.     

Fourier transform infrared analysis of plasma-polymerized hexamethyldisiloxane

The plasma-induced polymerization of hexamethyldisiloxane onto solid surfaces is studied by FTIR. An inductively coupled RF reactor was used to produce the thin polymer coatings. Analysis of the plasma polymer indicates a long chain polysiloxane structure resulting from the removal of some methyl groups from the monomer structure. Increasing the plasma power level from 30 to 100 W increased the chain length in the resultant polymer as indicated by the widening and splitting of the Si–O stretching absorptions. Thermal aging of the vapor phase polymer at 120°C for 1 h in vacuum and at 410°C for 30 min in a nitrogen atmosphere revealed the removal of some methyl groups from the polymer structure with temperature. TGA runs on the vapor phase polymer at 20°C/min in air showed the polymer retaining almost 65% of its weight at 1000°C. The residue remaining after the TGA run had very little organic content and may represent a glass type silicate network. Wettability values determined on coated glass slides revealed the hydrophobicity of the coatings with water contact angle values > 100°. SEM micrographs showed uniform and featureless coating on glass fibers which was etched by boiling water and was attributed to the loss of vapor phase polymer on the surface.     

Dielectric barrier discharge plasma induced surface modification of polyester/cotton blended fabrics to impart water repellency using HMDSO

Continuous treatment of polyester/cotton blended fabric samples was carried with hexamethyldisiloxane (HMDSO) plasma on the pilot scale atmospheric pressure plasma reactor. The mixture of helium and argon was used as carrier gas for generating dielectric barrier discharge plasma. The effect of discharge power and treatment time on the water repellent properties of samples were evaluated with contact angle (CA) and spray test measurements. Spray test and CA results showed improved resistance to wetting with water. The effect of discharge conditions on the surface morphology and surface chemistry of plasma treated samples were investigated by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopic analysis, respectively. The presence of Si‐O‐Si and Si‐CH₃ groups in the structure of plasma polymer deposited at the surface of P/C samples was revealed by FTIR spectroscopy. Further, structural differences in HMDSO plasma polymer deposited under different discharge conditions were reported with reference to organic/inorganic nature of plasma polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Synthesis and characterization of poly(vinyl alcohol)/water glass (SiO2) nano‐hybrids via sol‐gel process

A new class of materials based on inorganic and organic species combined at a nanoscale level has received large attention recently. In this work the idea of producing hybrid materials with controllable properties is applied to obtain foams to be used as catalyst supporting. Hybrids were synthesized by reacting poly(vinyl alcohol) in acidic solution with water glass. The inorganic phase was also modified by incorporating a hexamethyldisiloxane as precursor. The hybrid aerogel powder was analyzed by scanning electron microscopy, TG‐DTA, Nitrogen adsorption–desorption, X‐ray diffraction and fourier transform infrared spectroscopy (FTIR) spectroscopy. The powder obtained had a higher porosity varying from 65 to 90% and the nanopore diameter ranged from 17 to 20 nm. The surface area and nanopore volume decreased as polymer content increased in the hybrids. The sharp decline in the weight observed at around 500°C accompanied an exothermic peak of the DTA curve. The sharp peak was observed around 211°C represents the DTA curve of Poly vinyl alcohol constituent in nano hybrids. The peak at 1638 cm^?1 in the FTIR indicated the formation of Si? O? PVA? O? Si bridge in aerogel powder. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The preparation and characterization of abrasion-resistant coatings on polycarbonate

A series of abrasion-resistant coatings based on methyltrimethoxysilane (MTMS), tetraethoxysilane (TEOS), and methacyloxypropyltrimethoxysilane (MEMO) were synthesized via a sol–gel method and applied to polycarbonate (PC) substrate. Through a comparison with an uncoated PC substrate, hardness, adhesion, and abrasion resistance of coated PC substrates were investigated. Fourier transform infrared (FTIR) spectra of these coatings before and after being cured indicated that the crosslinked structure of Si–O–Si was formed via the hydrolysis–condensation reactions of alkoxy silane. The optical test results showed that coated PC substrates possessed higher transmittance and lower haze than uncoated PC substrates. The hardness and adhesion data demonstrated that PC substrates coated with the hybrid coatings (MTMS/TEOS/MEMO coatings) possessed the greatest hardness and optimal adhesion. After 500 wear cycles, the PC substrate with MTMS/TEOS/MEMO coatings showed some grooves and wear tracks without any spallation or delamination, and there was a decrease of only 1.0–1.3% in transmittance and an increase of only 5.68–7.44% in haze. Whereas uncoated PC substrate and substrates with MTMS and MTMS/TEOS (molar ratio is 1.5:1) coatings exhibited a decrease of 3.3, 3.9, and 2.4% in transmittance and an increase of 30.19, 17.42, and 12.35% in haze, respectively.     

A new modified silicone–TiO2 polymer composite film and its photocatalytic degradation

The photodegradation of the silicone surfactant–TiO₂ composite films was characterized by FTIR, Raman spectroscopy, and scanning electron microscope. After photocatalytic degradation, the FTIR Si? O? Si peak intensity of the composite film remained unchanged, implying no cleavage of Si? O? Si bond. The above Si? O? Si peak intensity is sensitive to the polyoxyethylene chain length of the composite. The PEG10000‐silicone composite is more resistant to photodegradation than those composites with lower molecular weight of constituent PEGs. The wetting rates of the silicone surfactant–TiO₂ composites showed that modified silicone composite films exhibited hydrophobic nature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3341–3344, 2006     

Synthesis and thermal stability properties of boron‐doped silicone resin

In this article, a novel boron‐doped silicone resin (BSR) was synthesized by hydrolysis‐polycondensation method, with propyl‐triethoxysilane (PTES), dimethyl‐diethoxysilane (DMDES), and boric acid (BA) as starting materials, using absolute ethyl alcohol as solvent and hydrochloric acid as catalyst. The structures of the BSR were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X‐ray photoelectron spectroscopy (XPS), and gel permeation chromatography (GPC). FTIR spectra showed characteristic B? O? Si and Si? O? Si stretching modes. XPS and NMR results confirmed further that boron element was doped successfully into the main chains of the silicone resin as Si? O? B bond motifs, and hydroxyl groups from BA were condensed properly with Si? OH or Si? OR to form cross‐linked structure of BSR with narrowed molecular weight distributions in optimum experimental condition. The thermal stability of the BSR was studied by thermogravimetry analysis and derivative thermogravimetry. The thermal degradation temperature of the silicone resin improved greatly after doping element boron into the main chain, and the thermal stability of the BSR was influenced by the content of boron. The thermal degradation mechanism of this BSR was also discussed. The degradation process can be divided into two stages, the weight loss in the first stages may be corresponding to the loss of the small groups and weaker bonds in the chains, such as ? CH₃, and ? C₃H₇, the weight loss in the second stage may be corresponding to the loss of the group as ? OC₂H₅. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40934.     

Characterization of chemically modified wood fibers using FTIR spectroscopy for biocomposites

Chemical modifications of wood fibers (Lignocel® C120) were performed for biocomposite applications, and chemically modified wood fibers were analyzed by FTIR spectroscopy. NaOH treatment showed band shifts from Cell‐I to Cell‐II in FTIR spectra from 2902 cm^?1, 1425 cm^?1, 1163 cm^?1, 983 cm^?1, and 897 cm^?1 to 2894 cm^?1, 1420 cm^?1, 1161 cm^?1, 993 cm^?1, and 895 cm^?1 and the change in peak height at 1111 cm^?1 and 1059 cm^?1 assigned for Cell‐I structure. Silane treatment showed peak changes at 1200 cm^?1 assigned as Si? O? C band, at 765 cm^?1 assigned as Si? C symmetric stretching bond, at 700 cm^?1 assigned as Si? O? Si symmetric stretching, and at 465 cm^?1 assigned as Si? O? C asymmetric bending. Benzoyl treatment resulted in an increase in the carbonyl stretching absorption at 1723 cm^?1 and in band characteristics of aromatic rings (1604 cm^?1 and 710 cm^?1) and a strong absorption at 1272 cm^?1 for C? O band in aromatic ring. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of polyaluminocarbosilane and reaction mechanism study

Polyaluminocarbosilane (PACS) as the precursor of high‐temperature resistant SiC fibers was synthesized by reacting polycarbosilane (PCS) with aluminum(III)acetylacetonate [Al(AcAc)₃] at 310°C in N₂ under ambient pressure. The reaction mechanism and the structure of PACS were investigated in detail by FTIR, GPC, GC/MS, ESCA, and elemental analysis. The reaction was proven complex involving the formation of Si? O? Al and Si? Al? Si bonds, which were accompanied by the evolution of 3‐methoxy‐2,2‐dimethyl‐oxirane, 2,3‐dihydro‐[1,4]dioxine, pent‐3‐en‐2‐one, and 3‐ethyl‐but‐3‐en‐2‐one, and acetylacetone. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2787–2792, 2002     

Surface coating protective against oxidative plasma etching of polypropylene

Polypropylene (PP) sheets were coated with the ultrathin polymer layers by plasma polymerization of hexamethyldisiloxane and two other Si-containing monomers, and the protection effects from oxidative plasma etching were investigated. Etching was evaluated by the weight loss of PP sheets after the exposure to an oxidative plasma of O₂ or air. The effects of plasma polymer coating on the etching resistance were investigated with respect to the type of plasma polymer, thickness of a coating layer, oxidative plasma etching conditions, etc. Weight of the coated PP sheets was less changed and the substrates remained stable after a certain period of oxidative plasma treatments, during which time the original PP film had prominently lost weight. The importance of the crosslinked network with —Si— MPO components in plasma polymers on the etching resistance was suggested from the results. Infrared spectra were taken and analyzed with the plasma polymers after O₂-plasma treatments, and the increase in the Si—O structure was indicated by the increase in the peak intensity at 1023 cm⁻¹. Stabilization against oxidative etching was attributed to the crosslinked Si—O structure on the surface layer. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1049–1057, 1997     

Preparation and characterization of polysiloxane‐acrylate latexes with MPS‐PDMS oligomer as macromonomer

The latexes of polysiloxane and acrylate with methacryloxypropyl trimethoxysilane (MPS)–polydimethylsiloxane (PDMS) oligomer as macromonomer and Gemini surfactant as coemulsifier were prepared by emulsion copolymerization and characterized by ¹H‐nmr, gel‐permeation chromatography (GPC), FTIR, x‐ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). First, the oligomer of MPS‐PDMS (Si? O? Si chain length = 24) were synthesized by the hydrolysis of MPS and the ring‐opening polymerization of octamethyl tetracyclosiloxane (D₄), the ¹H‐NMR and FTIR spectra indicated that when the reaction time was prolonged to 2 h, more than 90% of ? Si (OCH₃)₃ groups were hydrolyzed; Then, the emulsion polymerization was performed with the oligomer as macromonomer and Gemini Surfactant as coemulsifier, the result of FTIR indicated that almost all the macromonomer had been exhausted because there was no C?C characteristic peaks in the spectrum. XPS investigation of the latexes showed that with the increase of siloxane content, more and more polysiloxane occupied the outer layer of the membrane, which agreed well with the conclusion of contact angle and AFM measurements. With Gemini surfactant as coemulsifier in the system, the PDMS content in the system could reach to 50%, which was far higher than the other reported value. © 2009 Wiley Periodicals, Inc. Journal of Applied Polymer Science, 2009     

Chemical Vapor Deposition Growth of Composite Silicon-Silica Nanowires from Silicon Monoxide Vapor

Si/SiO₂ nanowires were synthesized directly by and on silicon substrate surface without the use of a metal catalyst. Since these nanowires grow directly from the silicon substrate, they do not need to be manipulated or aligned for subsequent applications. The obtained nanowires are amorphous with diameters ranging between 50 to 200 nm and few micrometers in length. Parameters like heating temperature, deposition time, and carrier gas flow-rate were found critical in determining the size, structure, growth yield and morphology of the obtained nanowires. FTIR absorption spectra showed high intensity Si–O asymmetric stretching mode and no absorption for Si-Si backbone vibration mode at 620 cm^?1which indicates the non-crystalline nature of grown wires.     

Infrared spectroscopic study of SiOx film formation and decomposition of vinyl silane derivative by heat treatment. I. On KBr and gold surface

The free-radical copolymerization of vinyltrimethoxysilane (VTS) with vinylimidazole (VI) was carried out in benzene at 68°C. Thermooxidative degradation and the SiO_x film-formation mechanism of poly(VI-co-VTS) both on gold and KBr were studied with Fourier transform infrared (FTIR) spectroscopy. Reflection-absorption (R-A) spectra on gold were compared with transmission spectra on KBr. In the initial stage of heat treatment, the Si—O—Si bond formation was caused mainly by the residual water in the copolymer film. As heating time increased, however, both the water resulting from the thermal decomposition of the copolymer and the water vapor in air began to participate in the hydrolysis of the Si—O—CH₃ group followed by the condensation reaction. The structure of the SiO_x film became closer to the structure of SiO₂ with increasing heating temperature. In addition, the differences between the transmission spectra and R-A spectra were observed at the peaks related to Si—O—Si stretching due to the optical effect. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:775–784, 1998     

Property approach of Si based ZnO films under thermal shock

ZnO and Al-doped ZnO (AZO) films were deposited on p-Si(100) wafers using magnetron sputtering, the effect of thermal shock on Si based films and its interface were evaluated by various characterization methods such as in-situ nanoscratch, atomic force microscope (AFM), X-ray diffraction (XRD), fourier transform infrared (FTIR) spectra and ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS). The results show the adhesion strength of Si/ZnO interface is relatively stable under thermal shock, the surface grains of Si coated ZnO form dense clusters then refine them. XRD and FTIR show Si based films exhibit (002) orientation with good structural stability related to Zn–O bond, the interfacial reactions of Si based films could experience strong interaction through Si, Zn and O atoms located at Si/ZnO interface during thermal shock. Moreover, some comparatively prominent peaks are observed by UV-DRS, which caused by Si interacted with ZnO, the AZO films deposited on quartz glass substrates illustrate the optical properties are obviously influenced and degraded after thermal shock.     

Hydrophobic coating of silicate phosphor powder using atmospheric pressure dielectric barrier discharge plasma

A stable superhydrophobic coating was successfully deposited on commercial silicate‐based orange phosphor by using atmospheric pressure dielectric barrier discharge plasma with hexamethyldisiloxane (HMDSO) and HMDSO/toluene mixture as precursors. Owning to the good optical properties, the deposited film acts not only as a hydrophobic protective layer but also as an antireflection optical thin film capable of improving the phosphor photoluminescence efficiency. The plasma‐polymerized film based on Si?O?Si backbone containing methyl and phenyl nonpolar functional groups exhibited high‐water‐repellent characteristics. It was found that the water contact angle gradually increased with increasing the aging time and remained unchanged at about 140° after 1‐month aging. Besides, the thermal stability of the coated phosphor under high‐temperature condition was substantially enhanced by the aging. The findings of this work can contribute to improving the durability and reliability of the phosphor, eventually the long‐term stability of phosphor‐based light emitting diodes in practical applications. © 2014 American Institute of Chemical Engineers AIChE J, 60: 829–838, 2014     

Modification of polyethylene–octene elastomer by silica through a sol–gel process

In this study, tetraethoxysilane (TEOS) and a metallocene polyethylene–octene elastomer (POE) were chosen as the ceramic precursor and the continuous phase, respectively, for the preparation of new hybrids by an in situ sol–gel process. To obtain a better hybrid, a maleic anhydride‐grafted polyethylene–octene elastomer (POE‐g‐MAH), used as the continuous phase, was also investigated. Characterizations of POE‐g‐MAH/SiO₂ and POE/SiO₂ hybrids were performed by Fourier transform infrared (FTIR) and ²⁹Si solid‐state nuclear magnetic resonance (NMR) spectrometers, a differential scanning calorimeter (DSC), a thermogravimetry analyzer, and an Instron mechanical tester. The results showed that the POE‐g‐MAH/SiO₂ hybrid could improve the properties of the POE/SiO₂ hybrid because the interfacial force between the polymer matrix and the silica network was changed from hydrogen bonds into covalent Si? O? C bonds through dehydration of hydroxy groups in POE‐g‐MAH with residual silanol groups in the silica network. The existence of covalent Si? O? C bonds was proved by FTIR spectra. For the POE/SiO₂ and POE‐g‐MAH/SiO₂ hybrids, maximum values of the tensile strength and the glass transition temperature were found at 9 wt % SiO₂ since a limited content of silica might be linked with the polymer chains through the covalent bond. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 966–972, 2003     

Plasma polymerized membranes and gas permeability. II

Thin films were deposited onto porous substrates by plasma polymerization using three kinds of organosilicic compounds, tetramethylsilane (TMS), hexamethyldisiloxane (M₂), and octamethylcyclotetrasiloxane (D₄). Those composite membranes showed different characteristics of gas permeability. When D₄ was plasma-deposited onto a porous substrate, the composites membrane showed the highest oxygen permeability and the lowest oxygen-to-nitrogen permeability ratio. The composite membrane prepared from TMS showed the permeability characteristics opposite to the membrane obtained from D₄. Infrared spectrum of the polymer from D₄ resembles that of dimethylpolysiloxane. The plasma polymers from TMS and M₂ showed different profiles in Si? O absorption bands in the range 1100–1000 cm^-1 or in absorption bands of SiCH₃ groups in the range 850–750 cm^-1 from respective monomers. X-ray photoelectron spectroscopic observation indicated that all the plasma polymers contained more than two species of Si atom with different oxidation states. The greater part of Si atoms in plasma polymers took the same oxidation states in corresponding monomer. The gas permeability characteristics were closely related to the oxidation states of Si atom in the plasma polymers.     

Novel reactive diluents for UV/moisture dual‐curable coatings

The novel silicone‐modified polyacrylate reactive diluents for UV/moisture dual‐curable coatings were synthesized from N,N‐bis[3‐(trimethoxysilyl)propyl]amine and multifunctional acrylates such as ethoxylated trimethylolpropane triacrylate and polyethyleneglycol diacrylate through Michael addition reaction. Their structures were characterized by NMR and FTIR and their average molecular weights were determined by vapor pressure osmometry. With FTIR, it was found that the obtained diluents could be cured both by UV radiation and moisture mode. The ²⁹Si‐NMR showed that dimer was the main condensation product at the initial stage of moisture curing. The rheological behavior of the diluents investigated by rotary viscometer indicated they were very close to Newtonian fluid, and the viscosity of coatings decreased evenly with increasing concentration of reactive diluents in the coatings. In particular, they were found to be highly efficient in diluency and reactivity for UV polymerization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1500–1504, 2005     

CuO Impregnated mesoporous silica KIT-6: a simple and efficient catalyst for benzene hydroxylation by C–H activation and styrene epoxidation reactions

Copper oxide doped mesoporous KIT-6 materials were synthesized by ultrasonication as impregnation method. The highly ordered nature of mesoporous CuO-KIT-6 materials analyzed by low angle X-ray diffraction. The high surface area, pore diameter and mesoporous nature of synthesized materials were confirmed by BET surface area analysis. Si–O–Si, Si–OH and Cu–O–Si bonds in the framework of CuO-KIT-6 were verified by FTIR spectroscopy. The Cu²⁺ ← O^2? charge-transfer transitions and d–d transitions of dispersed Cu²⁺ on ordered mesoporous KIT-6 were identified by DRS UV–Vis spectroscopy. The morphology of the synthesized CuO-KIT-6 materials was analyzed by HR-SEM. The 3D ordered nature of CuO-KIT-6 confirmed by TEM analysis. The highly ordered 3D mesoporous CuO-KIT-6 materials are excellent catalyst for benzene hydroxylation reaction through C-H activation and styrene epoxidation reaction with 30 % aqueous H₂O₂. The catalyst CuO-KIT-6 itself showed a good conversion towards both reactions.     

Fabrication and cytotoxicity assessment of novel polysiloxane/bioactive glass films for biomedical applications

This work evaluates for the first time the cyto-compatibility of silicone (polysiloxane)/bioactive glass composite films produced by dip coating on stainless steel substrates using osteoblast-like (MG-63) cells. With the aim of creating corrosion resistant coatings for biomedical applications, bioactive glass (BG) of 45S5 composition was used as a filler in conjunction with commercial silicones (MK and H62C). Bioactive glass has the property of forming a direct bond to living bone, and polysiloxane is an attractive candidate for protective coatings due to its resistance to oxidation and corrosion. Suspensions based on polysiloxanes (MK/H62C) and micro-sized BG fillers were used for dip coating stainless steel substrates at room temperature, followed by curing in oxidative atmosphere at 260 °C and 500 °C. Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of Si–O–Si, Si–OR, Si–CH₃ and Si–OH groups on the substrate. Field emission scanning electron microscopy showed that the coatings were homogeneous with no obvious cracks or pinholes at relatively high concentrations of both polysiloxane and BG. The cell biology experiments confirmed that the expressed cell-morphology, analyzed on chosen surfaces, was pheno-typical for MG-63 cells after 48 h of incubation. On the film containing the lower amount of polysiloxane/BG the most dense cell layer was formed. Our results indicated that polysiloxane/BG composite films exhibited good cyto-compatibility at 260 °C and 500 °C and showed no toxicity toward MG-63 cells suggesting the potential of this composite for applications in medical implants.