Phenyltrimethoxysilane Research Articles

Fabrication of hybrid polyimide composites containing Ladder-like poly(phenyl-co-glycidoxypropyl)silsesquioxane)

Ladder-like structured poly(phenyl-co-glycidoxypropyl) silsesquioxanes with different ratios of phenyl to glycidyl group (LPS64 and LPS 82) were synthesized using simple hydrolysis reaction followed by condensation polymerization of phenyltrimethoxysilane (PTMS) and (3-glycidyloxypropyl)trimethoxysilane (GPTMS). Two series of hybrid polyimide composites (PI/LPS64 and PI/LPS82) with different contents of LPS (10, 20, and 30 wt%) were prepared by the chemical reaction of epoxy groups in LPS64 or LPS82 and the terminal amine groups in poly(amic acid). The dielectric constant (k) of hybrid PI composites (k = 1.3) was lower than that of pure polyimide (k = 2.9) and the degree of roughness was increased according to the increase of LPS contents. The dispersion of LPS in the PI matrix was improved due to the chemical bonding between LPS and PI. The thermal stability of PI/LPS82 was higher than that of PI/LPS64 due to the enhanced π-π stacking between PI matrix and LPS82 with more phenyl groups as compared to LPS64.

Precision integration of uniform molecular‐level carbon into porous silica framework for synergistic electrochemical activation in high‐performance lithium–ion batteries

AbstractThe development of advanced anode materials for lithium‐ion batteries that can provide high specific capacity and stable cycle performance is of paramount importance. This study presents a novel approach for synthesizing molecular‐level homogeneous carbon integration to porous SiO2 nanoparticles (SiO2@C NPs) tailored to enhance their electrochemical activities for lithium‐ion battery anode. By varying the ratio of the precursors for sol–gel reaction of (phenyltrimethoxysilane (PTMS) and tetraethoxysilane (TEOS)), the carbon content and porosity within SiO2@C NPs is precisely controlled. With a 4:6 PTMS and TEOS ratio, the SiO2@C NPs exhibit a highly mesoporous structure with thin carbon and the partially reduced SiOx phases, which balances ion and charge transfer for electrochemical activation of SiO2@C NPs resulting remarkable capacity and cycle performance. This study offers a novel strategy for preparing affordable high capacity SiO2‐based advanced anode materials with enhanced electrochemical performances.image

Threshold of Surface Initiator Concentration for Polymer Brush Growth by Surface-Initiated Atom Transfer Radical Polymerization.

The surface modification of various materials by grafting functional molecules has attracted much attention from fundamental research to practical applications because of its ability to impart various physical and chemical properties to the surfaces. One promising approach is the use of polymer brushes synthesized by atom transfer radical polymerization (ATRP) from surface-tethered initiators (SIs). In this study, for the purpose of controlling the grafting amounts/densities of polymer brushes, we developed a facile method to precisely regulate SI concentrations of SI layers (SILs) by serial dilution based on a sol-gel method. By simply mixing organosilanes terminated with and without an initiator group ((p-chloromethyl) phenyltrimethoxysilane (CMPTMS) and phenyltrimethoxysilane (PTMS), respectively) with tetraethoxysilane (TEOS), SI concentrations of SILs could be arbitrarily tuned precisely by varying dilution factors of (CMPTMS + PTMS)/CMPTMS (DFs, 1-107). The resulting SILs prepared at different DFs were highly smooth and transparent. X-ray photoelectron spectroscopy (XPS) also confirmed that the SIs were homogeneously distributed at the topmost surface of the SILs and their concentrations were proven to be accurately and precisely controlled from high to extremely low, comparable to theoretical values. Subsequent SI-ATRP in air ("paint-on" SI-ATRP) of two different types of monomers (hydrophobic/nonionic (2,3,4,5,6-pentafluorostyrene) and hydrophilic/ionic (sodium 4-styrenesulfonate)) demonstrated that polymer brushes with different grafting amounts/densities were successfully grafted only from SILs with DFs of 1-104 (theoretical SI concentrations: 3.9 × 10-4 ∼ 3.5 units/nm2), while at DFs of 105 and above (theoretical SI concentrations: <3.9 × 10-5 units/nm2), no sign of polymer brush growth was confirmed by thickness, XPS, and water contact angle data. Therefore, we are the first to gather evidence that the approximate threshold of SI concentration required for "paint-on" SI-ATRP might be on the order of 10-4 ∼ 10-5 units/nm2.

Influence of monomer concentration on structures of fully condensed polyphenylsilsesquioxanes

Fully condensed polyphenylsilsesquioxanes have been prepared via the hydrolysis and condensation of the same phenyltrimethoxysilane (PTMS) monomer in different concentrations. The effect of monomer concentration on molecular structure of the final products has been thoroughly investigated. Cage structured polyphenylsilsesquioxane (OPS) and ladder-like structured polyphenylsilsesquioxane (L-PPSQ) can be selectively synthesized from the same starting materials at lower and higher initial monomer concentrations. Meanwhile, online infrared detector, React IR TM15 was used to monitor the real time variation of the concentration and characteristic absorption peaks of any intermediate products that may exist. Then, React IR TM15 coupled with 29Si nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) were used to monitor and identify the intermediate species during the reaction. Mechanism studies indicated that the condensation reaction of OPS and L-PPSQ both proceed through a T1 structure dimer, which was formed by the quick hydrolysis of the PTMS monomer. As confirmed by 29Si-NMR, GPC and MALDI-TOF-MS, the synthesis mechanisms of OPS and L-PPSQ during the hydrolysis-condensation reactions were delineated.

Understanding Fenofibrate Release from Bare and Modified Mesoporous Silica Nanoparticles.

To investigate the impact of the surface functionalization of mesoporous silica nanoparticle (MSN) carriers in the physical state, molecular mobility and the release of Fenofibrate (FNB) MSNs with ordered cylindrical pores were prepared. The surface of the MSNs was modified with either (3-aminopropyl) triethoxysilane (APTES) or trimethoxy(phenyl)silane (TMPS), and the density of the grafted functional groups was quantified via 1H-NMR. The incorporation in the ~3 nm pores of the MSNs promoted FNB amorphization, as evidenced via FTIR, DSC and dielectric analysis, showing no tendency to undergo recrystallization in opposition to the neat drug. Moreover, the onset of the glass transition was slightly shifted to lower temperatures when the drug was loaded in unmodified MSNs, and MSNs modified with APTES composite, while it increased in the case of TMPS-modified MSNs. Dielectric studies have confirmed these changes and allowed researchers to disclose the broad glass transition in multiple relaxations associated with different FNB populations. Moreover, DRS showed relaxation processes in dehydrated composites associated with surface-anchored FNB molecules whose mobility showed a correlation with the observed drug release profiles.

Crystal Structure of New 1-Phenyl-Substituted Tribenzsilatranes

The family of practically requested “common” silatrane derivatives of triethanolamine X-Si(OCH2CH2)3N, 1, was enlarged with the first representatives of 3,4,6,7,10,11-tribenzo-2,8,9trioxa-5-aza-1-silatricyclo(3.3.3.0^1,5^)undecanes X-Si(O-para-R-C6H3)3N, tribenzsilatranes 2 (R = H (a), Me (b), F (c)), carrying the substituent R in the side aromatic rings. These compounds were prepared via the transesterification of phenyl trimethoxysilane with the corresponding triphenol amines and studied using XRD and DFT calculations. These derivatives of 1-X-(4-R-2,2′,2′′-nitrilotriphenoxy)silane are expected to have, as their parent “common” silatranes 1, diverse biological and pharma activities. A common characteristic feature of the molecular structures of both 1 and 2 is the presence of an intramolecular dative bond N→Si whose existence is evidenced by geometric and quantum topological (AIM) criteria. In the crystals, the length of this bond (dSiN) is noticeably longer in tribenzsilatranes than in 1. The results of DFT B3PW91/6-311++G(d,p) calculations suggest the reason for this to be the more rigid nature of the potential functions of the N→Si bond deformation in 2 compared to 1. The relative degree of “softness”/”hardness” of the potential functions can be assessed from the difference in the calculated values of dSiN in isolated molecules 1 and 2a–c and in their crystals.

The mixing properties, IR analysis and quantum chemical calculations of trimethoxylsilane derivatives with ethanol, 1-butanol, 1-pentanol and 1-octanol

The density, viscosity and speed of sound of trimethoxylsilane derivatives with ethanol, 1-butanol, 1-pentanol and 1-octanol have been measured at 298.15, 303.15, 308.15, 313.15 K, 318.15 and 323.15 K, respectively. The excess molar volume, viscosity deviation, excess Gibbs energy of activation of viscous flow, isobaric thermal expansivity and isentropic compressibility deviation were calculated from these results. The Redlich–Kister equation was used for the correlation. The calculated excess properties have been discussed according to the possible interactions formed between the molecules in the mixture using equimolar attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. In all of the compositions and experimental temperature ranges studied, the excess molar volumes were found to be negative for vinyl trimethoxy silane and phenyl trimethoxy silane with ethanol. This may be attributed to the close accumulation of molecules and easier formation of cross-association structures between the alkoxysilane molecules. However, the excess molar volume of the binary mixture of vinyl trimethoxy silane and phenyl trimethoxy silane with n-butanol, n-pentanol, and n-octanol was positive. Hydrogen bond fracture may play a leading role in this process. The excess molar volumes of the binary system comprised of trifluoropropyl trimethoxy silane with ethanol and 1-octanol were all positive. This may be attributed to the influence of steric hindrance, which makes it difficult for trifluoropropyl trimethoxy silane to form a cross-association structure with alcohol molecules.

The P/Si synergistic effect enduing epoxy resin with improved flame retardancy and outstanding mechanical properties

The bisphenol F epoxy resin (DGEBF) reacted with 10-(2,5-Dihydroxyphenyl)-10H-9-oxa-10-phospha-phenantbrene-10-oxide (ODOPB) and phenyltrimethoxysilane (PTMS) to obtain a novel epoxy resin containing both phosphorus and silicon (EP-P/Si). EP-P/Si exhibited evidently improved flame retardancy, with a limited oxygen index value of 33.4% and UL-94 V-1 rating acquired. In cone calorimeter test, its peak heat release rate (PHRR), total heat release (THR), average effective heat of combustion (av-EHC), and total smoke production (TSP) were reduced by 36.0%, 19.5%,11.5%, and 7.2% compared with neat epoxy resin (EP), respectively, indicating that the P/Si synergistic effect not only improved the flame retardancy but also inhibited the smoke release. The flame retardancy mechanism was studied by analysis of char residue and pyrolysis behavior in gas phase. Scanning electron microscopy (SEM) results exhibited that EP-P/Si formed a dense and compact carbon layer acting as a barrier to inhibit further combustion. And the Fourier transform infrared (FTIR) spectra, laser Raman spectroscopy (LRS), and X-ray photoelectron spectroscopy (XPS) results indicated that it had good thermal stability. In addition, the pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) results suggested that the phosphorus-containing radicals (·PO2) that had quenching effect existed in the gas phase. While the flame retardancy got improved, EP-P/Si also exhibited excellent mechanical properties, with an improvement of 31.8%, 6.2%, and 369.7% in tensile strength, flexural strength, and impact strength compared with EP, respectively.

Effect of external electron donor on stereoselective Copolymerization of isoprene and butadiene with MgCl2-Supported Ziegler-Natta catalyst

External electron donors (ED) play significant roles in regulating stereoselectivity and catalytic activity of MgCl2-supported (TiCl4/MgCl2) type Ziegler-Natta catalysts. Investigating the contribution of ED on copolymerization of isoprene (Ip) and butadiene (Bd) with TiCl4/MgCl2 Ziegler-Natta catalysts is little reported. Herein, we reported the effects of three alkoxysilanes including dimethyldimethoxysilane (DMDMS), diphenyldimethoxysilane (DPDMS), phenyltrimethoxysilane (PTMS) added as ED on trans-1,4 stereoselective copolymerization of Ip and Bd using TiCl4/MgCl2-triisobutylaluminium (Al(i-Bu)3) catalyst system. Copolymers generated by TiCl4/MgCl2 catalyst in the absence of ED featured the microstructure transformation from cis-1,4 and trans-1,4 mixed microstructure on initial stage to trans-1,4 dominated microstructure and the molecular weight (Mw) evolution from low Mw to high Mw, indicating the transformation from low trans-1,4 stereoselective active center C*-1 to high trans-1,4 stereoselective active center C*-2. Appropriate introduction of alkoxysilane donors improved the polymerization activity, trans-1,4 unit content and molecular weight of copolymer in the order of PTMS > DPDMS > DMDMS, while excess alkoxysilane donors caused the decrease in that of polymerization behaviors. Increasing polymerization temperature also promoted the enhance in catalytic activity and trans-1,4 stereoseletivity of TiCl4/MgCl2 catalyst in the presence of ED. The equilibrium between deactivation and activation effect strongly depended on alkoxysilane structure, concentration and temperature. Plausible mechanisms for stereoselective transformation of active centers in Ip and Bd copolymerization using MgCl2-supported type Ziegler-Natta catalyst were proposed in terms of special roles of ED.

Studies on Borosiloxane Oligomers from Mixtures of Vinyltriethoxysilane and Phenyltrialkoxysilanes

Polycondensation of boric acid (BA) with mixtures of phenyltriethoxysilane (PTEOS) and vinyltriethoxysilane (VTEOS) and with mixtures of phenyltrimethoxysilane (PTMOS) and vinyltriethoxysilane (VTEOS) in diglyme at 83–87 °C using HCl as catalyst resulted in vinyl-functionalized borosiloxane oligomers. Effect of variation of PTEOS:VTEOS and PTMOS:VTEOS ratio (keeping BA:alkoxysilanes ratio constant) and the effect of variation of BA:alkoxysilane (BA:PTEOS:VTEOS and BA:PTMOS:VTEOS) ratio on the solubility, thermal stability and ceramic residue were studied. The oligomers obtained were characterized by FTIR, GPC, pyrolysis GC and TGA. For PTEOS + VTEOS system all the oligomers were soluble in the reaction medium, but after removal of alcohol (byproduct) and diglyme (solvent), the oligomers obtained in the solid form were insoluble in common organic solvents. Unlike the PTEOS-based system, for PTMOS-based system the oligomers synthesized from monomer feed ratios (BA:PTMOS:VTEOS) 1:1:1 and 1:1.67:0.33 even after the removal of ethanol and diglyme are soluble in tetrahydrofuran, dioxane and diglyme. These two soluble oligomers show bimodal molecular weight distribution with $$\overline{{\text{M}}}_{{_{{\text{W}}} }}$$ of 3,650 and $${\overline{\text{M}}}_{{\text{n}}}$$ of 1860 for 1:1:1 mol ratio, and $$\overline{{\text{M}}}_{{_{{\text{W}}} }}$$ of 2,540 and $${\overline{\text{M}}}_{{\text{n}}}$$ of 1700 for 1:1.67:0.33 mol ratio. 29Si-NMR spectra of the soluble oligomers show peaks at − 69 and − 78 ppm which are attributed to T2 and T3 structures respectively. Thermogravimetric analysis of vinyl-functionalized borosiloxane oligomers from PTEOS and PTMOS indicates that the ceramic residue of the oligomers in argon atmosphere at 900 °C varies from 68 to 89% depending on the monomer feed ratio of BA to organoalkoxysilane ratio and phenyltrialkoxysilane to VTEOS ratio. With the increase in concentration of VTEOS in the monomer feed the thermal stability as well as the ceramic residue of the oligomers increase and a reverse trend is observed for variation of BA concentration. Pyrolysis of the oligomers produce C2, C3 hydrocarbons and benzene as the main pyrolysis products. Ceramic conversion of a typical oligomer was carried out at 900 °C, 1500 °C and 1650 °C in argon atmosphere. The ceramics obtained at 900 °C and 1500 °C are amorphous SiBOC which transform to β-SiC at 1650 °C.

Organic-inorganic (polysiloxane) crosslinked sulphonated poly(ether ether ketone ketone) hybrid membranes for direct methanol fuel cells

A series of Ph-m-SPEEKK/polysiloxanes organic-inorganic hybrid proton exchange membranes (HMs) were prepared. The Ph-m-SPEEKK was synthesized from 2-phenylhydroquinone and 1,3-bis(4-fluorobenzoyl)benzene, and sulphonated in a controlled way until a 1.60 meq g−1 ion exchange capacity was reached. The crosslinked polysiloxane phase (PSP) was prepared by the sol-gel route from PDMS as the linear fraction and phenyltrimethoxysilane (PTMS) as crosslinker, the non-crosslinked PSP contained only PDMS. The crosslinked PSP was characterized by FTIR and solid state 29Si NMR, which revealed that the PTMS is fully crosslinked in the PSP structure. SEM micrographs of the HMs showed no apparent macro phase separation of the organic-inorganic components. The macroscopic properties of the HMs investigated were water uptake, swelling, methanol permeability and proton conductivity. The methanol permeability of the crosslinked HMs decreased to a limiting value between 16.3 and 17.9 × 10−7 cm2 s−1 at 60 °C. A continuous increase of the proton ion conductivity (64.1–90.0 mS cm−1 at 80 °C and 95% RH) was achieved with the addition of increasing amounts of the crosslinked PSP content as compared with the non-crosslinked HM. The HM with a 20 wt% of PSP presented a proton conductivity of 90.0 mS cm−1 and an activation energy for proton transport of 17.2 kJ mol−1, both comparable to Nafion 117 and in a single DMFC test the electrode assembly fabricated with this HM reached a maximum power density of 38.0 and 30.5 mW cm−2 for 2 and 5 M methanol concentrations, respectively, higher than Nafion 117 and the pristine Ph-m-SPEEKK membranes.

Silane–based modified papers and their extractive phase roles in a microfluidic platform

Herein, some (modified) paper–based substrates were prepared and utilized as extractive phases in a microfluidic device and their extraction performances examined for analytes with different polarities. Reagents including hexadecyltrimethoxysilane (HDTMS), phenyltrimethoxysilane (PTES), (3-aminopropyl) triethoxysilane (APTES) and 3–(2,3–epoxypropoxy) propyltrimethoxysilane (EPPTMOS) were implemented for the modification process. Due to the induction of different silane functional groups, it was anticipated to have various interactions for the tested analytes. Eventually, the prepared paper sheets were used as extractive phases for solid–phase extraction within a microfluidic system. The microfluidic setup not only improves the mechanical stability of the paper–based phases but also facilitated the mass transfer process and decreases the energy consumption. The selected analytes contained antidepressant drugs, organophosphates and triazine toxins, having different structures and polarities. Afterward, the existing interactions between the paper–based sorbents and the selected analytes were investigated by Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA) for data analysis. According to the obtained data, the PTES modified surface paper was selected for quantitative investigation and optimization. The major parameters associated with the extraction performance were studied. A linear range was obtained for amitriptyline and trimipramine, 0.05–200 μg L−1, and the calibration graph for clomipramine was linear in the range of 0.02–200 μg L−1. The employment of microfluidic device in conjunction with gas chromatography-mass spectrometry led to the limits of detections of 0.005–0.01 μgL−1 for the antidepressant drugs. The relative recoveries for the tested drugs in urine samples were in the range of 95–103%.

Antifouling and antimicrobial coatings based on sol–gel films

Biofouling is an undesirable process in which biological molecules and organisms adhere to a surface. This process causes severe negative effects in various fields including healthcare, water distillation, and marine transportation. Therefore, its prevention is highly explored. Here, the prevention of biofouling by thin films, based on different sol–gel precursors, was studied. Specifically, films were formed by methyltrimethoxysilane (MTMOS), phenyltrimethoxysilane (PTMOS), 3,3,3-trifluropropyltrimethoxysilane (FTMOS), or 3-aminopropyltrimethoxysilane (APTMS) using spin-coating on glass. We found that hydrophobicity alone showed a moderate effect on the number of adsorbed bacteria onto the surface. The APTMS film showed, as expected, antibacterial properties and its combination with FTMOS led to a significant prevention of protein and bacterial adsorption. These results emphasize that a dual effect of antifouling and antibacterial properties, is preferred in the prevention of biomass on surfaces.

Silicone Resin-Based Composite Materials for High Thermal Stability and Thermal Conductivity

Insulated silicone/alumina (Al2O3) composites with high thermal stability and thermal conductivity were fabricated, in which the silicone resin was fabricated by a hydrolysis and condensation reaction with triethoxysilane (MTES), dimethyldiethoxysilane (DMDES) and phenyltrimethoxysilane (PhTMS). When the Al2O3 loading was 80 wt.%, the composite had only a 1.2% weight loss at 390°C. When the volume ratio of the 10 μm Al2O3 powder to 0.5 μm Al2O3 powder was controlled at 7:3, the silicone resin-based composite had thermal conductivity of 1.18 W m−1 K−1, which is 6.2 times as high as that of the pure silicone resin. Furthermore, the silicone/Al2O3 composite had dielectric strength of 87.5 kV mm−1.

Synthesis and thermal curing of liquid unsaturated polysilsesquioxane and its mechanical and thermal properties

The liquid unsaturated polyhedral oligomeric silsesquioxane (PMPOSS) has been successfully synthesized via the hydrolysis-condensation reaction of phenyltrimethoxysilane (PTMS) and methacryloxypropyl trimethoxysilane (MPS). The structures of PMPOSS were confirmed by FTIR, NMR, and MALDI-TOF MS, indicating eight cage structures with different ratios of phenyl and methacryloxypropyl appeared. After that, the PMPOSS was diluted with different concentrations of styrene to explore the best curing formula. The bending test results demonstrated PMPOSS diluted by 20 wt% styrene (PMPOSS20) possessed good mechanical properties, however, PMPOSS0 (self-polymerization of PMPOSS) had the lower values of peak-HRR, THR, TSR, and peak-SD, which were reduced by 44.4%, 21.7%, 49.1%, and 33.8% in comparison to PMPOSS20, respectively. In addition, pyrolysis products were analyzed in detail by TGA-FTIR and Py-GC-MS. The results showed that large amounts of inflammable organic compounds were released from PMPOSS20 caused by the polystyrene fragments and methacryloxypropyl.

Well-organized organosilane composites for adhesion enhancement of heterojunctions

Flexible copper clad laminate (FCCL) is the key base material for versatile applications such as mobile devices, wearable electronics, and point-of-care biosensors. Development of adhesiveless FCCL is urgent to achieve a thinner, lighter, and thermally stable substrate for advanced high-frequency (5G) applications. In this study, a co-silanization method is proposed to functionalize the polyimide (PI) surface for efficient metal immobilization and adhesion enhancement. The co-silanization treatment features the establishment of a barricade-like network structure by the assistant organosilane, trimethoxyphenylsilane (TMPS), to generate spatial confinement effect (SCE) to effectively control the positioning and grafting orientation of the functional organosilane, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (ETAS), on the PI film. Benefitting from the effective positioning and grafting, the two types of organosilanes form a composite well-organized molecular nanolayer which is in possession of strong tethering ability for metal attachment and immobilization. Compared to the mono-silanization system with ETAS only (0.652 kgf/cm), the co-silanization treatment (ETAS + TMPS) remarkably enhances the peel strength of the deposited metal layer on PI by 53% (~1 kgf/cm).

Effects of Phenyltrimethoxysilane and Polyvinyl Alcohol on the Properties of Methyltrimethoxysilane-based Silica Aerogels

Silica aerogels have attracted great attention owing to their outstanding properties such as ultralow density, high porosity, high surface area, and low thermal conductivities. Their poor mechanical properties and hydrophilicity constrain their practical applications. In this work, phenyltrimethoxysilane (PTMS) and polyvinyl alcohol (PVA) were added into methyltrimethoxysilane (MTMS)-based silica aerogels to enhance their mechanical properties. It was found that PTMS considerably improved the hydrophobicity of MTMS silica aerogels with an increase in water contact angles from 115° to 150°. The addition of PVA considerably increased the hardness, morphology, density, porosity, surface area, and thermal conductivity of MTMS silica aerogels. When PVA concentration was increased from 0 to 2 %, the aerogel hardness, density, and thermal conductivity were also increased from 0 to 14 %, 0.072 to 0.11 g/cm3, and 0.035 to 0.046 W/m.K. In contrast, the aerogel became less porous and the porosity reduced from 97.2 % to 95.72 % and BET surface area decreased from 389 to 43 m2/g.

The Effect of Filler Loading and Silane Treatment on Kenaf Core Reinforced Polyurethane Composites: Mechanical and Thermal Properties

This investigation was aimed to study the mechanical and the thermal properties behavior of kenaf core (untreated and treated with silane)–polyurethane composites. Three different types of silane coupling agent were used to treat kenaf core (KC) which were, trimethoxyphenylsilane (TMPS), vinyltrimethoxysilane (VTMS), and tetramethoxyl orthosilicate (TMOS). The concentration of silane was varied from 0 to 3%. Silanization of KC filler is measured by the weight percentage gain (WPG), scanning electron microscopy and energy dispersive X-ray analysis. Kenaf core–polyurethane (KCP) composites were prepared using a one-shot process. Tensile, flexural and thermogravimetric analysis was carried out it to study mechanical and thermal properties of the KCP. Among the three types of silane, the most effective one for property improvement was TMPS. The results from TMPS showed tensile and flexural agreed to each other that TMPS was the suitable chemical to be used as a coupling agent for KC filler in the preparation of KCP composite.

Evolution from UV emission of phenyl groups to visible emission of pyrolytic nanocarbons dispersed in fumed silica: Alternative insight into photoluminescence of carbon nanodots

SiO2:C nanopowder, luminescent in ultraviolet and visible spectral ranges, was synthesised using fumed silica as morphological matrix (specific surface of 295 m2/g) and phenyltrimethoxysilane (PhTMS) as carbon precursor. Fumed silica was impregnated by toluene solution of PhTMS followed by drying and annealing at 600 °C. Two series of SiO2:C nanocomposites with different carbon concentration were synthesised and studied. The main idea of the study was to explore the correlation of structural reconstruction and evolution of photoluminescent properties of carbon moieties. Chemically modified fumed silica exhibited ultraviolet (UV) photoluminescence band at about 330 nm originated from phenyl groups. After calcinations at 600 °C two overlapped emission bands were found at about 380 nm and 420 nm in “low-carbon” SiO2:C, while “high-carbon” series exhibited broad but homogeneous emission band peaked at about 440–450 nm. One more characteristic emission band at 495 nm in SiO2:C appeared and developed under intense ultraviolet radiation. Evolution of light emission from ultraviolet to visible was analysed in correlation with structural reconstruction of carbon examined by FTIR spectroscopy, X-ray photoelectron spectroscopy, high resolution scanning transmission electron microscopy, and electron energy loss spectroscopy. The nature of light emission of pyrolytic carbon moieties in SiO2:C nanopowder was discussed in frame of the concepts of polycyclic carbon clusters and their aggregates based on the analogy with polycyclic organic molecules and luminescent carbon nanodots.

Flame Retardancy, Mechanical Properties and Antibacterial Activity for Polyester Fabric Coated with a Sol-gel Coating and Pomegranate Rind

This manuscript aimed to improve the ignition, mechanical properties and antibacterial activity of polyester fabric irradiated with UV/Ozone (for 30 minutes) after coated with sol-solution and pomegranate rind natural dye (PRND). Phenyltrimethoxysilane (PTMS) was used to form siloxane bonds as the main chain of the sol coating. The effect of (PRND) concentration was studied. The Fourier transform infrared (FTIR), illustrated the inter-chemical reaction between (-OH) groups in sol-solution with the free radical on the irradiated polyester fabric. Adding different amounts of PRND during solsolution synthesis, lead to increase reduction percent of gram-negative (E. coli) and gram-positive (S. aureus) bacteria and improve the thermal and mechanical properties with no flame retardancy effect. The flame chamber (UL/94), limiting oxygen index (LOI), and EN ISO 11925 tests were used to investigate the ignition properties of the treated and untreated specimens.