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An optimized recipe for 3D printing of Mullite-based structures was used to investigate the effect of MgO sintering additive on the processing stages and final ceramic properties. To achieve dense 3:2 mullite, ceramic filaments were prepared based on an alumina powder, a methyl silicone resin, EVA elastomeric binder and MgO powder. Using 1 wt% MgO and a dwell time of 5 h at 1600 °C, a dense mullite structure could be obtained from filaments with a diameter of 1.75 mm. Ceramic structures with and without sintering additive were printed in vertical and horizontal direction, to investigate the effect of printing direction on mechanical strength after sintering. Using four-point bending test, it was demonstrated that by using MgO, the printing orientation did not affect the mechanical strength significantly anymore. The low Weibull modulus could be explained by the closed porosity that emerge during the degassing of the preceramic polymer due to cross-linking.

Changes in the pore size, porosity, compressive strength, and thermal conductivity of closed-pore foam glass with a pore size of 450 µm upon the addition of 0–24 wt% of polysiloxane at a low sintering temperature of 750 °C were investigated. Micro-Raman analysis demonstrated the uniform dispersion of polysiloxane after sintering, and it was confirmed that the entire foam glass processed to have closed pores. With increasing polysiloxane, the pore size decreased from 452 μm to 131 μm, and the porosity decreased from 62% to 41%. The compressive strength increased from 2.0 to 5.7 MPa, and the thermal conductivity also increased from 0.146 to 0.233 W/m·K. However, when more than 15 wt% of polysiloxane was added, the thermal conductivity exceeded 0.160 W/m·K, rendering unsuitable as an insulating material. Therefore, we fabricated closed-pore foam glass with proper pore size and porosity, a strength of 4.1 MPa, and a low thermal conductivity below 0.160 W/m·K by adding 15 wt% of polysiloxane at a low sintering temperature.

The study considers the mechanical properties and temperature resistance of partially pyrolysed composites reinforced with various fibres. The composites were prepared by pyrolysis at 650 °C, where only partial conversion of the polymer to the inorganic SiOC structure takes place in the matrix. Such a hybrid matrix bears resemblance to polymeric materials in a density and Young's modulus, but oxidation resistance and creep behaviour are closer to silicate glasses. Pyrolysis also ensures that the whole composite material is non-flammable with very low potential for releasing toxic gases during a fire. Three types of glass fibres (E-glass, R-glass, E-CR-glass fibres), two types of basalt fibres, and two types of high-strength (HS) carbon fibres were used as reinforcements. The mechanical properties - Young's and shear moduli, flexural strength, and fracture toughness - were measured at room temperature. Thermogravimetric measurements and creep tests of these composites allowed estimation of their temperature resistance and fire resistance. The results obtained suggest that the materials under investigation can be applied as panels or shells in the building industry and in transportation facilities.

The construction of silicone elastomers crosslinked by a natural crosslinker under a catalyst-free method is highly desirable. Herein we present catalyst-free silicone elastomers (SEs) by simply introducing tannic acid (TA) as a natural crosslinker when using poly (aminopropylmethylsiloxane-co-dimethylsiloxane) (PAPMS) as the base polymer. The crosslinked bonding of these SEs can be easily changed from hydrogen bonding to covalent bonding by altering the curing reaction from room temperature to heating condition. The formability and mechanical properties of the SEs can be tuned by altering various factors, including processing technique, the amount of TA and aminopropyl-terminated polydimethylsiloxane, the molecular weight and -NH2 content of PAPMS, and the amount of reinforcing filler. The hydrogen bonding was proved by the reversible crosslinking of the elastomers, which can be gradually dissolved in tetrahydrofuran and re-formed after removing the solvent. The covalent bonding was proved by a model reaction of catechol and n-decylamine and occurred through a combination of hydroxylamine reaction and Michael addition reaction. These elastomers exhibit good thermal stability and excellent hydrophobic property and can bond iron sheets to hold the weight of 500 g, indicating their promising as adhesives. These results reveal that TA as a natural product is a suitable “green” crosslinker for the construction of catalyst-free silicone elastomers by a simple crosslinking strategy. Under this strategy, TA and more natural polyphenols could be certainly utilized as crosslinkers to fabricate more organic elastomers by selecting amine-containing polymers and further explore their extensive applications in adhesives, sealants, insulators, sensors, and so forth.

Water repellent is an important functional finish for cotton fabric. However, cotton fabrics often have poor washing resistance and other performances after actual finishing. In this study, based on the structural characteristics of cotton fiber and durability of water repellent, a cross-linked amino long-chain alkyl polysiloxane (CAHPS) was first prepared, and then reacted with modified silica. Finally, a chemically bonded organic–inorganic nanohybrid cross-linked polysiloxane (rSiO2–CAHPS) was fabricated. Furthermore, the rSiO2–CAHPS was emulsified to obtain a durable fluorine-free water repellent. The water repellent finishing for cotton fabric was carried out by the pad–dry–cure process. After finishing, the cotton fabric had good resistance to conventional liquids and excellent washing resistance, and still maintained good water repellency after 30 rounds of soaping. Moreover, properties including air permeability, mechanical property and whiteness are hardly affected after finishing. SEM and XPS characterization show that a layer of dense silicon film is formed on the surface of cotton fabric by rSiO2–CAHPS water repellent. The existence of nanosilica can improve the surface roughness of cotton fibers. The synergistic effect of fiber matrix, nanoparticles and CAHPS endows the fabric with a micro/nano-multi-scale micro-rough structure, which improves the water repellency of cotton fabric after water repellent finishing.

In order to improve the mechanical properties of SiO2 aerogels, PHMS/VTES-SiO2 composite aerogels (P/V-SiO2) were prepared. Using vinyltriethoxysilane (VTES) as a coupling agent, the PHMS/VTES complex was prepared by conducting an addition reaction with polyhydromethylsiloxane (PHMS) and VTES and then reacting it with inorganic silica sol to prepare the organic–inorganic composite aerogels. The PHMS/VTES complex forms a coating structure on the aerogel particles, enhancing the network structure of the composite aerogels. The composite aerogels can maintain the high specific surface area and excellent thermal insulation properties, and they have better mechanical properties. We studied the reaction mechanism during preparation and discussed the effects of the organic components on the structure and properties of the composite aerogels. The composite aerogels we prepared have a thermal conductivity of 0.03773 W·m−1·K−1 at room temperature and a compressive strength of 1.87 MPa. The compressive strength is several times greater than that of inorganic SiO2 aerogels. The organic–inorganic composite aerogels have excellent comprehensive properties, which helps to expand the application fields of silicon-based aerogels.

Transparent low-temperature cured gels were prepared using PDMS-DGE, a selected amine (DAP, DETA, and TAEA) and up to 30% of an organic liquid component – ethanol, t-butanol, or benzene. A mixture of the components was kept at 50 °C long enough to ensure completion of reaction that involves opening of diglycidyl ether (DGE) group and formation of an isopropanol-amine link. Hansens solubility parameters (HSP) were used to explain the influence of compatibility of PDMS, amine used for curing, and a liquid component. The properties and radiation stability (D = 50 kGy, γ-radiation) of obtained gels were studied using impedance spectroscopy, Soxhlet extraction, thermal analysis and ATR-FTIR spectroscopy. Even though amine segments are a minor component of a polymer gel-network, they had major influence on gel properties while liquid component was of secondary importance. The most stable were the gels prepared with a branched triamine, TAEA, regardless of the liquid components. Diamines DAP and particularly DETA produced soft and less stable gels. Influence of liquid components depended on the difference of its solubility parameters to that of both PDMS and the amine used for curing. In ATR-FTIR spectra of most of the irradiated gels amide absorption was observed. It indicates degradation at the isopropanol-amine link. However, no overall degradation was observed in those gels. So called “dangling chains” may have formed and remain entangled in the gel-network. Additionally, free-radicals formed in the PDMS segment of polymer network likely crosslinked thus compensating for degradation at isopropanol-amine links what contributed to stability specially of PDMS-TAEA gels.

Asymmetric porous SiOC membranes with different pore characteristic and membrane morphology were produced for the first time by adapting the phase inversion tape casting technique to the polymer-derived ceramic route. Polymethyl siloxane (MK) was used as a ceramic precursor. The produced tapes were pyrolyzed under N2 atmosphere. The structure and surface characteristics were tailored by changing the pyrolysis temperatures (600 and 1000 °C), polyvinylpyrrolidone and solid loading. Scanning electron microscopy analysis revealed the asymmetric morphology composed by a thin skin-layer (average pore size

Conventional carbonate-based liquid electrolytes have safety issues related to their high flammability and easy leakage. Therefore, it is essential to develop alternative electrolytes for lithium-ion batteries (LIBs). As a potential candidate, solid-polymer electrolytes (SPEs) offer enhanced safety characteristics, while to be widely applied their performance still has to be improved. Here, we have prepared a series of UV-photocrosslinked flexible SPEs comprising poly(ethylene glycol) diacrylate (PEGDA), trimethylolpropane ethoxylate triacrylate (ETPTA), and lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) salt, with the addition of polydimethylsiloxane with acrylated terminal groups (acryl-PDMS) to diminish the crystallinity of the poly(ethylene glycol) chain. Polysiloxanes have gained interest for the fabrication of SPEs due to their unique features, such as decrement of glass transition temperature (Tg), and the ability to improve flexibility and facilitate lithium-ion transport. Freestanding, transparent SPEs with excellent flexibility and mechanical properties were achieved without any supporting backbone, despite the high content of lithium salt, which was enabled by their networked structure, the presence of polar functional groups, and their amorphous structure. The highest ionic conductivity for the developed cross-linked SPEs was 1.75 &times, 10&minus, 6 S cm&minus, 1 at room temperature and 1.07 &times, 4 S cm&minus, 1 at 80 &deg, C. The SPEs demonstrated stable Li plating/stripping ability and excellent compatibility toward metallic lithium, and exhibited high electrochemical stability in a wide range of potentials, which enables application in high-voltage lithium-ion batteries.

The chemical synthesis of polysiloxanes from monomeric starting materials involves a series of hydrolysis, condensation and modification reactions with complex monomeric and oligomeric reaction mixtures. Real-time monitoring and precise process control of the synthesis process is of great importance to ensure reproducible intermediates and products and can readily be performed by optical spectroscopy. In chemical reactions involving rapid and simultaneous functional group transformations and complex reaction mixtures, however, the spectroscopic signals are often ambiguous due to overlapping bands, shifting peaks and changing baselines. The univariate analysis of individual absorbance signals is hence often only of limited use. In contrast, batch modelling based on the multivariate analysis of the time course of principal components (PCs) derived from the reaction spectra provides a more efficient tool for real-time monitoring. In batch modelling, not only single absorbance bands are used but information over a broad range of wavelengths is extracted from the evolving spectral fingerprints and used for analysis. Thereby, process control can be based on numerous chemical and morphological changes taking place during synthesis. &ldquo, Bad&rdquo, (or abnormal) batches can quickly be distinguished from &ldquo, normal&rdquo, ones by comparing the respective reaction trajectories in real time. In this work, FTIR spectroscopy was combined with multivariate data analysis for the in-line process characterization and batch modelling of polysiloxane formation. The synthesis was conducted under different starting conditions using various reactant concentrations. The complex spectral information was evaluated using chemometrics (principal component analysis, PCA). Specific spectral features at different stages of the reaction were assigned to the corresponding reaction steps. Reaction trajectories were derived based on batch modelling using a wide range of wavelengths. Subsequently, complexity was reduced again to the most relevant absorbance signals in order to derive a concept for a low-cost process spectroscopic set-up which could be used for real-time process monitoring and reaction control.

This research investigates the preparation and characterization of new organic&ndash, inorganic geopolymeric foams obtained by simultaneously reacting coal fly ash and an alkali silicate solution with polysiloxane oligomers. Foaming was realized in situ using Si0 as a blowing agent. Samples with density ranging from 0.3 to 0.7 g/cm3 that show good mechanical properties (with compressive strength up to &asymp, 5 MPa for a density of 0.7 g/cm3) along with thermal performances (&lambda, = 0.145 &plusmn, 0.001 W/m&middot, K for the foamed sample with density 0.330 g/cm3) comparable to commercial lightweight materials used in the field of thermal insulation were prepared. Since these foams were obtained by valorizing waste byproducts, they could be considered as low environmental impact materials and, hence, with promising perspectives towards the circular economy.

New hybrid materials using kaolin and the organosilicas methyl-polysiloxane (MK), methyl-phenyl-polysiloxane (H44), tetraethyl-ortho-silicate (TEOS) and 3-amino-propyl-triethoxysilane (APTES) were obtained by sol-gel process. These materials presented specific surfaces areas (SBET) in the range of 20–530 m2 g−1. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed remarkable differences between the kaolin and hybrid structures. Thermogravimetric analysis (TGA) revealed that the hybrid materials presented higher thermal stability when compared with their precursors. The electronic properties of the materials were also studied by Ultraviolet-Visible Diffuse Reflectance Absorption (DRUV) and Diffuse Reflectance spectroscopy (DR), where a new absorption band was observed located around 400–660 nm. In addition, these materials exhibit a decrease in DR from 30% to 70% in the blue-cyan green region and are significantly more transparent in the UV region than the kaolin, which could be useful for photocatalysis applications. These results show that the electronic structure of the final material was changed, indicating a significant interaction between the kaolin and the respective silica derivative. These findings support the main idea of the hybridization afforded by pyrolysis between kaolin and organosilica precursors. In addition, as a proof of concept, these hybrid materials were successfully employed as photocatalyst in the photoreduction of Cr(VI) to Cr(III).

In this study, the thermo-mechanical properties of networked, polysiloxane/polyether-based, hybrid polymer electrolytes are optimized with the aim of enabling room-temperature operation in lithium metal-polymer batteries. The structural parameters of the electrolytes (polyether chain length, cross-linking and salt concentration) are varied in order to get the best tradeoff between conductivity and mechanical stability. The optimized material has a conductivity close to 1.5·10 −4 S cm −1 at room temperature and a shear storage modulus of 50 kPa up to 100 °C. The effect of TiO 2 nano-particles is also studied with the results showing an overall ambiguous effect on the materials properties. Finally, one of the materials with the highest conductivity is used as electrolyte in a Li/LiFePO 4 cell. This cell has good rate capability and cyclability due to the high conductivity of the electrolyte. However, the high conductivity is reached at expense of the mechanical stability and the resulting electrolyte proves to be too weak to work as an efficient barrier against lithium dendrite growth.

WOS: 000406286800016, In this study, a novel polysiloxane-based gel agent (PSGA) was synthesized by using poly(dimethylsiloxane-co-alkylmethylsiloxane) and used as a gel agent for gel-valve-regulated lead-acid batteries. A PSGA was characterized by Fourier transform infrared, zeta meter, scanning electron microscopy, and energy-dispersive X-ray analysis. The electrochemical characterization of the gel system for the optimization of some parameters, such as concentration of gel agent, stirring rate, and agitation time, was conducted by cyclic voltammetric and electrochemical impedance spectroscopic analyses. The optimum concentration of the gel agent was determined as 6 wt% of the PSGA to form the best gel structure. The mechanical parameters related to the formation of a suitable gel structure were also investigated. The optimum stirring rate and agitation time were determined as 500 rpm and 2.5 h, respectively. The charge-discharge tests were applied to the gel system, and the highest capacity was determined in the PSGA-based gel system as 10 mAh at the end of the 100th cycle. The capacity of non-gelled system was the lowest., SAN-TEZ program of the Ministry of Science, Industry and Technology, Republic of Turkey [00897. STZ. 2011-1]; Anadolu University; Ericsson Turkey, This work was supported by the SAN-TEZ program (No. 00897. STZ. 2011-1) of the Ministry of Science, Industry and Technology, Republic of Turkey; Anadolu University; and Ericsson Turkey. Y. Sahin thanks Prof. Dr. Kadir Pekmez, Prof. Dr. Ender Suvaci, and Oktay Uysal for their supports to this study. M. Gencten thanks the TUBITAK-BIDEB.

The sol&ndash, gel polymerization of alkoxysilanes is a convenient and widely used method for the synthesis of silicon polymers and silicon&ndash, organic composites. The development of new sol&ndash, gel precursors is very important for obtaining new types of sol&ndash, gel products. New condensation polymer precursors containing consecutive silicon atoms&mdash, decaisopropoxycyclopentasilane (CPS) and dodecaethoxyneopentasilane (NPS)&mdash, were synthesized for the preparation of polysilane&ndash, polysiloxane material. The CPS and NPS xerogels were prepared by the sol&ndash, gel polymerization of CPS and NPS under three reaction conditions (acidic, basic and neutral). The CPS and NPS xerogels were characterized using N2 physisorption measurements (Brunauer&ndash, Emmett&ndash, Teller, BET and Brunauer-Joyner-Halenda, BJH), solid-state CP/MAS (cross-polarization/magic angle spinning) NMRs (nuclear magnetic resonances), TEM, and SEM. Their porosity and morphology were strongly affected by the structure of the precursors, and partial oxidative cleavage of Si-Si bonds occurred during the sol&ndash, gel process. The new condensation polymer precursors are expected to expand the choice of approaches for new polysilane&ndash, polysiloxane.

(Meth)acrylic terpolymers carrying siloxane (Si), fluoroalkyl (F) and ethoxylated (EG) side chains were synthesized with comparable molar compositions and different lengths of the Si and EG side chains, while the length of the fluorinated side chain was kept constant. Such terpolymers were used as surface-active modifiers of polydimethylsiloxane (PDMS)-based films with a loading of 4 wt%. The surface chemical compositions of both the films and the pristine terpolymers were determined by angle-resolved X-ray photoelectron spectroscopy (AR-XPS) at different photoemission angles. The terpolymer was effectively segregated to the polymer&minus, air interface of the films independent of the length of the constituent side chains. However, the specific details of the film surface modification depended upon the chemical structure of the terpolymer itself. The exceptionally high enrichment in F chains at the surface caused the accumulation of EG chains at the surface as well. The response of the films to the water environment was also proven to strictly depend on the type of terpolymer contained. While terpolymers with shorter EG chains appeared not to be affected by immersion in water for seven days, those containing longer EG chains underwent a massive surface reconstruction.

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH3)2R’NR]+, where R = C12, C14, C16, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

Siloxanes are adaptable species that have found extensive applications as versatile materials for functionalising various surfaces and as building blocks for polymers and hybrid organic-inorganic systems. The primary goal of this review is to report on and briefly explain the most relevant recent developments related to siloxanes and their applications, particularly regarding surface modification and the synthesis of graft copolymers bearing siloxane or polysiloxane segments. The key strategies for both functionalisation and synthesis of siloxane-bearing polymers are highlighted, and the various trends in the development of siloxane-based materials and the intended directions of their applications are explored.

The flame resistance of applied coating materials affects the safety of innovative technological solutions. Silicone-containing polymeric materials are one of the most economical solutions in the field of coatings due to the effect of the unique combination of very good thermal, resistance, and surface properties. The rich chemistry of silicon compounds, which results in their very good thermal stability, allows their use as flame-resistant coating materials or as flame retardants in polymer composites. In this review, the flame resistance of PDMS systems based on their thermal degradation data, as well as possible paths of thermal degradation depending on external conditions including the effect of additives, flame resistance of hybrid silicone-containing coating materials and most important innovative applications of these materials, are reviewed. Very good results from the use of organic silicon compounds as fire retardants in polymers obtained by many research teams are one of the promising ways of overcoming the health, safety, and availability concerns of traditional halogenated fire retardants.

Phenyl hydrogen polysiloxanes of different structures were prepared, and LED packaging silicone rubbers were made from these polysiloxanes. The hardness, elongation, tensile strength and anti-yellowing of the LED packaging silicone rubbers on lamps were characterized. The results show that phenyl hydrogen polysiloxanes of resin structures had lower molecular weight, and that the cured silicone rubbers exhibited higher hardness, tensile strength, crosslink density and lower gas permeability. Phenyl hydrogen polysiloxanes of oil structures had higher molecular weight, and the cured silicone rubbers from these polysiloxanes exhibited lower volume expansion coefficient, higher hot and cold impact cycles and less change in hardness during the aging process. The study results further showed that the degree of change in hardness, yellowing, gas permeability, sulfuration and volume expansion coefficient was reduced by using phenyl hydrogen polysiloxanes of resin-oil structures as crosslinking agents, enabling the combined performance advantages of both resin-structure and oil-structure rubbers. DOI: http://dx.doi.org/10.5755/j01.ms.24.2.18494

New antifouling (AF) coatings were designed and manufactured exploiting the proven foul-release (FR) properties of amphiphilic systems and comparing them with fully hydrophobic and hydrophilic systems. The novel strategy implied a simple synthesis route that involves exclusively the chemistry of polyurethanes. The system was indeed constituted by a corrosion resistant polysiloxane-polyester hybrid resin as binder, rich in highly reactive hydroxyl groups that make the polymer associable to the polyol of a polyurethane couple. Hydrophilic and hydrophobic moieties were introduced in the form of lateral chains of isocyanate hardeners. The system resulted easily implementable due to the combination of commercially available raw materials and the rapid kinetic of the reaction. This method was used to prepare amphiphilic, as well as fully hydrophilic and hydrophobic systems, which were spray coated on construction steel samples. The coating wettability was analysed on all samples through the measurement of wetting hysteresis, highlighting the amphiphilic behaviour of the formulations. The highest amphiphilic character was detected on the hydrophilic reference sample, probably due to the highest mobility of PEG-ilate chains under this configuration. Anti-fouling properties were determined by the evaluation of the retention rate of two alive Mediterranean marine organisms, Mytilus Edulis and Ulva Intestinalis, on the surface of samples. A further test was carried out to evaluate the AF/FR properties against a natural protein probe, namely egg white. The test carried out with natural organisms proved the suitability of all the proposed strategies to the implementation of effective AF/FR marine paints. The egg white test assessed that the highest efficiency in AF/FR activity was detained by the fully hydrophobic systems. The observation of the surface of the samples by SEM in back scatter modality revealed that the chemical patterning of the hydrophobic scenario could play a significant role in the development of such behaviour.

Polysiloxanes, which can add high softness and lubricity to treated textiles, have been proposed as softening post-finishing agents for fabric. However, the hydrophobicity of the finished fabric is not satisfactory. In this work, long-chain fluoroalkyl acrylate was used to modify the polysiloxane, aimed at improving hydrophobicity of the finished fabric and retaining its softness simultaneously. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectra (1H/13C NMR), and thermogravimetric analysis (TGA) were used to characterize the chemical structure and thermal stability of the as-prepared polymer. The modified polysiloxane was tested as a finishing agent. Its film morphologies on the fabric surface and on a silicon wafer were determined. Chemical compositions and performance properties of the finished fabric were investigated. By bonding long-chain fluoroalkyl, the modified polysiloxane presented good thermal stability. Due to the combined effect of the low surface free energy of the perfluorinated side chains and the relatively high surface roughness of the cotton fibers, the treated fabric had favorable hydrophobicity with a WCA of 144.7° on its surface. In addition, their softness was increased, but the color remained unchanged.

International audience; The main objective of this work focused on the chemical modification of polyamide 12 (PA12) properties through the reaction with a hydride‐terminated polydimethylsiloxane (PDMS‐SiH). The investigated PA12/PDMS‐SiH blend was compatibilized by ruthenium derivative catalyzed hydrosilylation reaction in molten state. This original route enhanced interfacial adhesion and avoid PDMS‐SiH leaching phenomenon between the two immiscible phases. More specifically, the size of PDMS‐SiH domains in the blend decreased from around 4 μm to 800 nm and from 30 to 1 μm after compatibilization with 10 and 20 wt % PDMS‐SiH, respectively. For the best compatibilized PA12/PDMS‐SiH blend, the introduction of PDMS lowered the surface free energy and the PA12‐based blend turned from hydrophilic to hydrophobic behavior, as evidenced by the water contact angle measurements. Gas permeability and CO2/H2 and CO2/He gas selectivity were also improved with the increase in PDMS content. Besides, the mechanical properties were enhanced with 13% increase in Young's modulus after in situ compatibilization with 15 wt % PDMS‐SiH. Thermal stability was also improved after compatibilization as the initial degradation temperature of reactive blends obviously increased compared with nonreactive ones.

Linear polyurethanes were obtained the reaction of 1,6-hexamethylene diisocyanate with poly(ɛ-caprolactone)diol and butane-1,4-diol. Synthesis was carried out in the presence of 1, 3 and 5 wt.% of polydimethylsiloxane-poly(methyl methacrylate) core–shell nanopowder. Solutions of resulting polyurethanes were cast on PTFE plates and dried at 140 °C to form films. The presence of structures originating from modifier was confirmed by IR and XPS spectroscopy. DSC analysis revealed the presence of crystalline phase in all samples. Contact angles were determined using standard fluids and surface free energy parameters were calculated. The results of these investigations proved that modification with silicone-acrylic nanopowder resulted in significant increase in hydrophobicity of polyurethane surfaces Changes in surface characteristics were also reflected in surface images obtained in AFM studies. It is suggested that the polyurethane composites obtained in this study can be tested as coatings for biomedical applications.

International audience; A series of new polymer electrolytes based on polydimethylsiloxane bearing 1-N-methylimidazolium-pentyl iodide side chains, (PILs) with different ionic functionality have been synthesized and characterized. In order to decrease the PILs viscosity and improve the ionic transport, ILs and organic solvent were added. The physiochemical and electrochemical properties of these PILs and their blends with ILs i.e. 1-methyl-3-propylimidazolium iodide (MPII) or 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide (MPI TFSI), including density, glass transition temperature, viscosity, ionic conductivity, ionicity and diffusion coefficient were determined. Furthermore, the effect of ethylene carbonate (EC) on the physicochemical and electrochemical properties of PILs was also evaluated in terms of ionic conductivity and diffusion coefficient.

A series of novel polyurethanes containing cross-linked siloxane in the side chain (SPU) were successfully synthesized through a sol-gel process. The SPU was composed of 0%–20% N-(n-butyl)-3-aminopropyltriethoxysilane (HDI-T) modified hexamethylene diisocynate homopolymer. The effects of HDI-T content on both the structure and properties of SPU were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical properties tests, gel content test, water contact angle measurement and water absorption test. FT-IR, XPS and XRD results confirmed the successful incorporation of HDI-T onto polyurethanes and the formation of Si–O–Si. The surface roughness and the Si content of SPU enhanced with the increase of HDI-T content. Both crystallization and melting temperature shifted to a lower point after the incorporation of HDI-T. The hydrophobicity, tensile strength, Young’s modulus and pencil hardness overall increased with the increasing of HDI-T content, whereas the thermal stability and the elongation at break of SPU slightly decreased.

A novel linear &alpha, &omega, di (chloro phosphoramide)-terminated polydimethylsiloxane (CPN-PDMS) was successfully synthesized and utilized as a formaldehyde-free water-repellent and flame-retardant for cotton fabrics. The flame retardancy of treated cotton fabrics was estimated by limiting oxygen index (LOI) test, vertical flammability test, and cone calorimetry test. The cotton fabrics treated with 350 g/L CPN-PDMS obtained excellent flame retardancy with an LOI value of 30.6% and the char length was only 4.3 cm. Combustion residues were studied using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analysis. Results show that CPN-PDMS can effectively enhance water repellency and fire resistance of cotton fabrics. Furthermore, the breaking strength test and the whiteness test strongly prove that the tensile strength and whiteness of the treated cotton fabrics were slightly lower than that of the pure cotton fabrics. The wash stability test showed that after 30 laundering cycles, the treated cotton fabrics still had an LOI value of 28.5% and a water-repellent effect of grade 80, indicating that CPN-PDMS was an excellent washing durability additive. In summary, these property enhancements of treated cotton fabrics were attributed to the synergistic effect of silicon-phosphorus-nitrogen elements in CPN-PDMS.

Poly(urethane-siloxane) networks based on hydroxyethoxy propyl terminated poly(dimethylsiloxane) (PDMS) as the soft segment and 4,4′-methylenediphenyl diisocyanate (MDI) and two hyperbranched polyesters with different core as the hard segments were characterized by swelling experiments, thermal analyses (DSC and TG), thermomechanical analysis (DMTA), X-ray scattering studies, SEM and AFM analyses, water contact angle and water absorption measurements, as well as surface free energy determination. From these studies, structure–property relationships were elucidated. Hyperbranched polyesters based on 2,2-bis(hydroxymethyl)propionic acid and ethoxylated pentaerythritol or di-trimethylolpropane as core (BH-40 and HBP-4) were used as crosslinkers for the samples of different series. Both series are composed of samples having different PDMS (i.e., soft segment) content. The crosslinking density and extent of hydrogen bonding showed an influence on the polyurethane (PU) properties. It was found that higher crosslinking density and better thermal stability of PUs based on BH-40 compared to HBP-4 based PUs are due to the less dense structure of BH-40. DMTA experiments revealed that the networks exhibit two glass transition temperatures, of the soft and hard segments, and one secondary relaxation process. The crosslinking density and extent of the microphase separation increased and thermomechanical properties were improved with decreasing content of PDMS. With increasing PDMS content, the surface of the polyurethane networks became more hydrophobic, the surface free energy decreased and thermal stability was improved. The obtained results revealed that synthesized PUs have good thermal and thermomechanical properties, which can be tailored for the potential use in the coating technology by changing the type of hyperbranched polyester or PDMS content.

The purpose of this work was to characterize the viscoelastic behaviour of oral mucosa and compare it with the dynamic mechanical properties of different soft liners. For this purpose, a sample of pig oral mucosa and six commercialized soft liner samples have been investigated. A comparison was also carried with the first suitable hard rubber for dental prosthetics: vulcanite. Creep recovery (CR) and dynamic mechanical analysis (DMA) have been used to determine the mechanical modulus of oral mucosa and soft liners respectively. The Poisson ratio is used to compare mucosa bulk modulus and soft liner shear modulus. The biomechanical concept of conventional complete dentures needs a good adjustment of dynamic mechanical impedance between the base and oral mucosa. The viscoelastic mechanical property of the oral mucosa as a referent biopolymer has been confirmed in vitro. The modulus value, adjusted for old patients in physiological conditions, is in the order of 3 MPa. This study underlines the plasticization effect of absorbed water on the mechanical properties of the underlying tissue. This study allows us to define some characteristics of the most adapted biomaterial according to the clinical exigency. The required biomaterial must display the following properties: compatibility and chemical resistance with biological environment perpetuated mechanical properties during physiological conditions and clinical use, good adjustment of dynamic mechanical impedance with supporting mucosa and easy sample processing.

The purpose of this study was to synthesize polydimethylsiloxanes by heterogeneous catalysis, based on the polymerization of the hexadecamethylcyclooctasiloxane (D8) by an environment-friendly solid catalyst (Maghnite-H + ). Maghnite-H + is a natural Algerian clay of the montmorillonite type, prepared by activation with sulfuric acid, the impact of this activation was observable in the XRD spectrum, by the increase in the interlayer spacing (d 001 ) resulting from the intercalation of hydronium ions between layers. The molecular structure of the obtained polymer was determined by different chemical methods of analysis such as IR, 1 H NMR, and 13 C NMR. The thermal behavior of the polysiloxane obtained was confirmed by DSC. In order to achieve the best possible yield and at the same time to get a polymer of high molecular mass, the operating conditions have been set at t = 8 h and T = 70 °C after the reaction was repeated several times. The average molecular mass and the polydispersity index were measured by GPC. A reaction mechanism has been suggested to show the action of the Maghnite-H + during the reaction. Copyright © 2018 BCREC Group. All rights reserved Received: 8 th March 2017; Revised: 27 th July 2017; Accepted: 1 st August 2017; Available online: 22 nd January 2018; Published regularly: 2 nd April 2018 How to Cite : Kherroub, D.E., Belbachir, M., Lamouri, S. (2018). Green Polymerization of Hexadecamethylcyclooctasiloxane Using an Algerian Proton Exchanged Clay Called Maghnite-H + . Bulletin of Chemical Reaction Engineering & Catalysis , 13 (1): 36-46 (doi:10.9767/bcrec.13.1.993.36-46)

A commercially available polysiloxane was used as a preceramic polymer for solution freeze casting to obtain directionally aligned porous silicon oxycarbide. We show how choice of solvent, polymer concentration, and freezing rate can affect the final pore network of the freeze-cast ceramic. Solvents of cyclohexane and camphene resulted in dendritic pores, while tert-butyl alcohol (TBA) produced intersecting cellular pores in the freeze-cast ceramic. Characterization of pore size distribution by mercury intrusion porosimetry of ceramics produced from cyclohexane–polysiloxane solutions with varying polymer concentrations and freezing rates demonstrated trends consistent with solidification theory. Fourier transform infrared spectroscopy and X-ray diffraction were employed to confirm that the freeze-casting process resulted in silicon oxycarbide of comparable chemistry and crystallinity to that produced via traditional preceramic polymer processing techniques.

Poly(3-aminopropylmethylsiloxane) has been modified with acrylonitrile via aza Michael addition and a broad range of modified oligomers have been prepared with CN:NH₂ ratio ranging between 0.1 and 1. NMR and FTnIR analysis reveals that acrylonitrile modification proceeds without formation of tertiary amines. Modified oligomers have been characterized by DSC and analysis of Tg reveals that the adducts are self-associated probably due to weak hydrogen bonding and dipole interactions. The modified oligomers with a modification degree higher than 0.4 were miscible with DGEBA. The low and high temperature relaxations of the cured thermosets have been measured by DMTA. In addition to the commonly observed β₂ relaxation, a new β₁ process linked by an isosbestic point to β₂ has been found. β₁ is attributed to an extended segment comprising the pendant propionitrile group as well as the aminopropyl segment that connects tertiary amines to the polysiloxane backbone. Elastic modulus as well as the α relaxation can be tuned from high Tg and high rubbery modulus to low Tg and high damping thermosets changing the nitrile content. The experimental network structure obtained from elastic measurements and the Tg were related through well established structure-property relations. Authors wish to thank Spanish Ministerio de Economía y Competitividad for funding this work under grant MAT2010-17091.

Polycondensation reaction of 70PhSiO 3 / 2 .30Ph 2 SiO 2 / 2 (Ph=C 2 H 5 ) polysiloxane has been almost completed by treating the corresponding gel with a diethyl ether-aqueous NaOH immiscible two phase liquids. The phenyl-modified siloxane gel is dissolved in diethyl ether phase which is immiscible with an NaOH aqueous solution. After stirring the immiscible solution vigorously, the glass-ether phase is extracted and then subjected to evaporation to leave glass precursor. The phenyl-modified siloxane glass is prepared by melting the precursor at 200°C over 1 h, in which the polycondensation reaction of siloxane network is almost completed. It is found that the obtained siloxane glass shows a softening temperature around 80°C and this value remains unchanged even after heat-treatment over 200 h at 200°C.

Glass fibers (GF) are widely used as a reinforcing material for many polymer products; to form very strong and light weight materials. Surface flaw generated by contact makes the glass fiber highly sensitive. Defects or cracks in the surface of glass fiber threaten the mechanical strength of the fiber that deteriorates the durability of glass fiber. Coating can play crucial role by forming single or multiple molecular layers on the glass fiber in rectifying the surface flaws and modify surface properties of glass fiber either online or offline. In this experiment, coating was introduced on the fiber surface by continuous impregnation of fiber with a solution of polymer in a padder in order to improve the mechanical strength of glass fibers. The tensile properties of GF roving after coating were studied. The experimental results showed that the tensile properties of coated GF roving were improved significantly compared to uncoated GF roving. DOI: http://dx.doi.org/10.5755/j01.ms.20.1.3432

We synthesized novel amphiphilic triblock copolymers of the ABC, ACB, ACD and ADC types composed of polystyrene (A), hydrophilic polyethylene glycol-modified polystyrene (B), hydrophobic/lipophilic polysiloxane-modified polystyrene (C) and hydrophobic/lipophobic perfluoroalkyl-modified polystyrene (D) blocks. Surface domain morphology, chemical composition and wettability of the polymer films were investigated by atomic force microscopy (AFM), angle-resolved X-ray photoelectron spectroscopy (XPS) and contact angle analyses, respectively. Each analysis proved that the surface (nano)structure of the polymer films was strongly affected by the chemistry of the triblock copolymer and weakly depended on the sequential position of the blocks in the copolymer. The low surface energy component (C or D) populated the surface in any case. Contact angle and XPS measurements carried out on the films after six–seven days of immersion in water showed that triblock copolymers containing the lowest surface energy fluoroalkyl block (D) underwent surface reconstruction to a greater extent than those possessing the polysiloxane block (C).

International audience; A facile and low-cost strategy to improve stability and conversion efficiency of CdSe film electrodes prepared by chemical bath deposition (CBD) onto FTO/glass substrates, is described. The naked CdSe film electrodes, with band gap value 1.8 eV, photo-corroded under the photoelectrochemical (PEC) working conditions and exhibited no photocurrent. The CdSe film peeled out in short times. Attempts made to enhance stability and efficiency of naked CdSe electrodes, by chemical etching or pre-scratching the FTO surface with fine sand-paper, failed to improve film PEC characteristics. Annealing the glass/FTO/CdSe film also failed to improve its PEC stability or efficiency. When coated with the electro-active species Tetra(-4-pyridyl)porphyrinatomanganeseIII/II sulfate embedded inside polysiloxane films (MnPyP/Polysil) the CdSe films did not peel out under the PEC conditions. The coated electrode (glass/FTO/CdSe/MnPyP/Polysil) clearly exhibited photocurrents. Pre-annealing the naked CdSe film at 350 °C, followed by coating with MnPyP/Polysil further enhanced the electrode PEC characteristics. Additional heating of the prepared glass/FTO/CdSe/MnPyP/Polysil electrode at 120 °C also enhanced its PEC characteristics. The mode of action of the MnPyP/Polysil coating has been attributed to its ability to behave as a charge transfer catalyst at the solid/liquid interface. The new technique described here could also be potentially valuable for other types of thin film electrode materials.

The synergistic effects of methylphenyl-polsiloxane solid powder and organophosphate flame retardant for polycarbonate (PC) were investigated by limiting oxygen index(LOI), and cone calorimeter. It was found that the LOI of the flame-retarded PC (FR-PC) with polysiloxane and organophosphate binary flame retardants didn’t increase in comparison with that of FR-PC containing a single species flame retardant. The cone calorimeter results show that the heat release rate (HRR) of the PC/polysiloxane/organophosphate(PX230) composition is approximately 50% lower than that of the PC/polysiloxane or the PC/PX230. Total heat release (THR) of PC/polysiloxane/PX230 also significantly reduce in comparison with that of PC/polysiloxane and PC/PX230 binary composites, which indicates a clear synergistic effect of the polysiloxane and PX230 in the PC flame retardant composites. The CO production rate of the PC/polysiloxane/PX230 during combustion is slightly lower than that of the virgin PC. So the combination of the polysiloxane with PX230 used in PC could synergic inhibit the combustion heat release, and achieve environmental friendly fire-retardant effect.

International audience; The comparison between physical properties and chemical structures of several polysiloxanes was studied at initial state and upon ageings. Techniques such as densimetry, gel permeation chromatography, FTIR spectroscopy, thermogravim- etric analysis coupled with IR spectroscopy and the new tool photo-DSC were used to give assessments of average mo- lecular weight, chemical evolution, cristallinity and thermal stability. Different types of ageing such as thermal ageing (60°C and 100°C), photo-ageing and acid vapour ageing were performed. After ageing we observed an evolution of chemical structures and physical properties for all samples. The main pathway of degradation is given for each sample. It results in oxidation, chain scission or cross-linking. Cross-linking levels are dependant on the type of ageing, the chemical structure and the initial rate of cristallinity. Cross-linking reactions are favoured after photo-ageing. Oxidation is higher for polysiloxane with aliphatic carbon chain.

Cycloaliphatic epoxy resin has been successfully thermally cured using a polyamino siloxane oligomer as hardener. The curing reaction was followed by infrared spectroscopy in the near range, and thermal transitions were measured by dynamic mechanical thermal analysis. The use of accelerants and a plasticizer (dodecylphenol), and different curing schedules were explored. Cured materials showed high Tg values (around 125&-164 °C), and the analysis of laser scanning confocal microscopy images showed that they are homogeneous in the microscale. The authors would like to express their gratitude to the Dinater (MAT2007 63722) and Interfases (S 0505/MAT0227) projects for financial support.

International audience; This paper deals with the study of spin coating processes for the deposition of polysiloxane-based thin films. Specific developments are proposed in order to adapt the hydrodynamic laws theory to the spin coating of Maxwellian liquids. Theoretical and experimental results are compared, evidencing a good fit and enabling to define the Maxwellian law for the studied polysiloxane polymer. Finally, the theoretical developments are successfully extended to the BCB 4026 and SU-8 3050 photosensitive resins.

An overview is given on polymer electrolytes based on organo-functionalized polyphosphazenes and polysiloxanes. Chemical and electrochemical properties are discussed with respect to the synthesis, the choice of side groups and the goal of obtaining membranes and thin films that combine high ionic conductivity and mechanical stability. Electrochemical stability, concentration polarization and the role of transference numbers are discussed with respect to possible applications in lithium batteries. It is shown that the ionic conductivities of salt-in-polymer membranes without additives and plasticizers are limited to maximum conductivities around 10-4 S/cm. Nevertheless, a straightforward strategy based on additives can increase the conductivities to at least 10-3 S/cm and maybe further. In this context, the future role of polymers for safe, alternative electrolytes in lithium batteries will benefit from concepts based on polymeric gels, composites and hybrid materials. Presently developed polymer electrolytes with oligoether sidechains are electrochemically stable in the potential range 0-4.5V (vs. Li/Li+ reference). © by Oldenbourg Wissenschaftsverlag, München. Deutsche Forschungsgemeinschaft --This work was part of the research program A2 within the collaborative research center “SFB 458”, funded by the Deutsche Forschungsgemeinschaft. We thank K. Funke, R. Banhatti, H. Eckert, C. Cramer-Kellers, M. Schönhoff, A. Heuer, R. Pöttgen, B. Krebs, T. Nilges, N. Stolwijk, L. van Wüllen and D. Wilmer for helpful discussions, thanks also to all colleagues in the SFB 458 for the excellent collaboration. Finally, we would like to acknowledge the collaboration with D. Richter, R. Zorn, and W. Pyckhout-Hintzen on SANS experiments in Jülich, the collaboration with S. Passerini and M. Winter regarding the electrochemical analysis of polymer electrolytes in lithium ion cells, and we thank H. Gores (University Regensburg) and G. Röschenthaler (Jacobs University Bremen) for preparing and making available a number of novel lithium salts.

WOS: 000257977000016, PubMed ID: 18717174, Objective: The aim of the present study was to evaluate the clinical performance of four denture soft liners up to 12 months. Materials and methods: Thirty-three edentulous patients who experienced difficulties when using hard denture bases because of changes in denture-supporting tissues were accepted for the study and randomly received Molloplast B, GC Reline Soft, Silagum Comfort, or Mollosil Plus relines. Performance of the materials was evaluated using nine criteria at 3, 6, and 12 months: physical integrity, surface detail, adhesion, color, odor, plaque accumulation, resilience, hygiene, and mucosal condition. A four-point categorized scale (1=poor, 2=fair, 3=good, 4=excellent) was used. Unscheduled maintenance events and the presence of fungal colonization were also recorded. Results: The percentage of patients available at 3, 6, and 12 months were 91%, 91%, and 66%. Main reasons for dropouts and discontinuation were fractured dentures and patient dissatisfaction. At 6 months, 96% of the performance scores were good or excellent and the largest changes were observed for physical integrity, surface detail, color, and fungal colonization. Fungal colonization was the most commonly observed problem and was the only reason of failure at 12 months. Conclusions: The clinical performance of all soft liners was slightly impaired over the 12-month observation. Except for cases showing extensive fungal colonization, the observed changes in clinical performance did not necessitate remaking of the dentures. Mollosil Plus showed a performance comparable to that of Molloplast B, and the other materials had slightly lower performance especially in terms of fungal colonization.

Çapan, Rifat (Balikesir Author), Non-centrosymmetric Langmuir-Blodgett (LB) thin films exhibit a temperature-dependent electric polarisation, which is known as the pyroelectric effect. Alternate layer LB films were prepared by transferring polysiloxane alternately with eicosylamine from a subphase of Millipore water (18 M Omega cm(-1)) incorporating different metallic ions onto a 50 nm thick thermally evaporated aluminium substrate. Pyroelectric and dielectric measurements were performed on LB films with a sandwich structure comprising film. Pyroelectric coefficients of these LB films are measured at several temperatures. The dielectric constant and dielectric losses were obtained to determine the pyroelectric figure of merit values of these LB films, which were calculated in the range of 24.9 to 56.7 mu C m(-2) K-1. (c) 2006 Elsevier B.V. All rights reserved.

We developed an efficient method to prepare a hybrid inorganic-organic composite based on polyvinyl alcohol (PVA) and polysiloxane using the sol-gel disc technique. Antigen obtained from Yersinia pestis was covalently immobilized onto these discs with glutaraldehyde and used as solid phase in ELISA for antibody detection in serum of rabbits experimentally immunized with plague. Using 1.25 microg antigen per disc, a peroxidase conjugate dilution of 1:4,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. These values are similar to those used for PVA-glutaraldehyde discs, plasticized filter paper discs and the polyaniline-Dacron composite discs. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates, with the amount of antigen being one fourth that employed in conventional PVC plates (5 microg/well). In addition to the performance of the polysiloxane/PVA-glutaraldehyde disc as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application.

Chemically modified field effect transistors for the selective detection of several cation and anion activities in aqueous solution are described. For obtaining sensors of high durability, novel polysiloxane membranes have been developed which contain different side groups to tune their intrinsic properties. These polysiloxane membranes show good performance in life time experiments. The ion selectivity has been tuned by incorporation of various novel ion receptor molecules, yielding sensors with high selectivities for sodium, potassium, lead, cupper, cadmium, silver, nitrate, nitrite, fluoride, and dihydrogen phosphate.

Capacitance sensors were prepared by spin-on coating interdigital thin-film structures with chemically modified polymers. The sensors were characterized electrically by their frequency response behaviour and spectroscopically by Fourier transform infrared spectroscopy (FTIR). The electrical response of the structures was monitored by impedance spectroscopy at different frequencies, temperatures and partial pressures of organic aliphatic and aromatic compounds in air. At an optimum frequency and temperature, the capacitance part in the sensor response was then used for systematic sensor tests. The results are explained by a solution of organic gases in the polymer. Implications are discussed to tailor the polymer coatings for specific selectivities.