Agent Γ-aminopropyltriethoxysilane Research Articles

RAFT polymerization of MMA in channels of different mesoporous materials

A series of mesoporous silica (MS) materials, including rod-like and spherical SBA-15, spherical MCM-41, and MCM-48, was successfully synthesized and modified by silane coupling agent γ-aminopropyltriethoxysilane. The modified MS was utilized as a microreactor for solution reversible addition–fragmentation transfer (RAFT) polymerization of methyl methacrylate (MMA) using xanthate as a chain transfer agent and azodiisobutyronitrile as an initiator. Notably, modified MS had a low specific surface area and pore volume while maintaining the original morphological structure. Given to the confinement effects, poly(methyl methacrylate) (PMMA) prepared from internal mesoporous channels had higher molecular weight and initial thermal decomposition temperature than those from conventional RAFT polymerization. Moreover, PMMA obtained from spherical SBA-15 and modified MCM-48 exhibited the highest molecular weight (Mn = 8.78 × 104 and Mn = 7.43 × 104, respectively). This work provided a novel approach in designing a polymer microstructure for a more comprehensive application, such as in drug release.Graphical abstract

Dual Modification of Porous Ca-P/PLA Composites with APTES and Alendronate Improves Their Mechanical Strength and Cytobiocompatibility towards Human Osteoblasts.

Synthetic implants are used to treat large bone defects that are often unable to regenerate, for example those caused by osteoporosis. It is necessary that the materials used to manufacture them are biocompatible and resorbable. Polymer-ceramic composites, such as those based on poly(L-lactide) (PLLA) and calcium phosphate ceramics (Ca-P), are often used for these purposes. In this study, we attempted to investigate an innovative strategy for two-step (dual) modification of composites and their components to improve the compatibility of composite components and the adhesion between PLA and Ca-P whiskers, and to increase the mechanical strength of the composite, as well as improve osteological bioactivity and prevent bone resorption in composites intended for bone regeneration. In the first step, Ca-P whiskers were modified with a saturated fatty acid namely, lauric acid (LA), or a silane coupling agent γ-aminopropyltriethoxysilane (APTES). Then, the composite, characterized by the best mechanical properties, was modified in the second stage of the work with an active chemical compound used in medicine as a first-line drug in osteoporosis-sodium alendronate, belonging to the group of bisphosphonates (BP). As a result of the research covered in this work, the composite modified with APTES and alendronate was found to be a promising candidate for future biomedical engineering applications.

An efficient approach to strengthen polyvinyl alcohol physical hydrogel via in situ growing NH2-decorated polysiloxane structures

This study aims to reveal a novel approach to synthesize high strength polyvinyl alcohol (PVA) physical hydrogel through the freezing-thawing method, with γ-aminopropyl triethoxysilane agent as an auxiliary factor. It was shown that the synthesized PVA-based hydrogels had high water content, excellent mechanical properties, and good biocompatibility. The saline agent γ-aminopropyl triethoxysilane in PVA solution was hydrolyzed and polymerized into NH2-decorated polysiloxane structures, which could be anchored to the porous PVA network and acted as a very effective hydrogen bond acceptor/donor, and thereby arousing a large increase in strength and toughness of PVA hydrogels. Meanwhile, the hydrophobic polysiloxane structures also increased the crystal cross-linking of PVA network and promoted a well-distributed porous PVA network. This work provides a simple and efficient route to synthesize high strength PVA-based physical hydrogel with desirable structure and properties.

Investigation of the nano-hydroxyapatite with different surface modifications on the properties of poly(lactide-co-glycolide acid)/poly(trimethylene carbonate)/nano-hydroxyapatite composites

Nano-hydroxyapatite (HA) was successfully treated by three different surface modification methods of oleic acid (OA), silane coupling agent γ-aminopropyl triethoxysilane (KH550), and ethenyltrimethoxysilane (YDH171), respectively. Then, the treated HA and unmodified HA with 8 wt% were introduced into PLGA/PTMC blends, respectively. And the fracture morphology, thermal property, crystallization behavior, mechanical properties, surface wettability, and in vitro bioactivity of PLGA/PTMC/HA ternary composites were investigated. The results showed that the PLGA/PTMC/HA composite with the HA surface modified by OA had the highest mechanical properties, while the PLGA/PTMC/HA composite with the HA treated by silane coupling agent YDH171 had the excellent toughness, compared to the other samples. Moreover, the cells’ proliferation results confirmed that the ternary composites exhibited better biocompatibility. All the results suggested that the surface modification of HA was an ideal method in this study, and they would be potential to be used in the field of bone repair in the future.

High impact strength of polypropylene composites with complex titanate whiskers/multiwalled carbon nanotubes

Isotactic polypropylene (PP) composites achieved high impact strength by melt mixing with complex titanate whiskers/multiwalled carbon nanotubes (MWCNTs). The complex fillers, obtained via coupling agent γ-aminopropyl triethoxysilane, triggered additional reinforcement with stiff backup of whiskers and strengthened interfacial adhesion generated from MWCNTs, forwarding positive synergy on the PP composites. In presence of compatibilizer maleic anhydride-grafted polypropylene, 5 wt% of the complex fillers brought about impact strength 6.3 ± 0.3 kJ/m2 to the composite, which was 103% higher than PP. Meanwhile, tensile strength was also improved with 34.8 ± 0.5 MPa as compared with that of PP (32.6 ± 0.3 MPa). Morphology witnessed by scanning electron microscope revealed that the complex fillers favored dispersion of MWCNTs in polymer matrix, fulfilling bridging for reinforcement. Detection of differential scanning calorimetry also indicated that the complex fillers facilitated crystallization of PP in the composites. Upon high impact strength and improved tensile property, the PP composites could find potentials with facile processing manipulation in applications.

Influence of treated nano-alumina and gas-phase fluorination on the dielectric properties of epoxy resin/alumina nanocomposites

In this study, epoxy resins incorporated with nano-alumina (nano-Al 2 O 3 ) are prepared with different concentrations of 0, 1, 3 and 5 wt%. The obtained epoxy resin/Al 2 O 3 nanocomposites are subsequently fluorinated using F 2 /N 2 mixture (F 2 /N 2 20% v/v) at 0.05 MPa and 40°C. The nano-Al 2 O 3 is treated with silane coupling agent γ-aminopropyltriethoxysilane (KH550) to restrict aggregation. The chemical bonding is examined by Fourier-transform infrared spectroscopy. The cross-section and surface morphological analyses are performed using scanning electron microscopy. In addition, the DC surface resistivity is measured using a resistivity test fixture. The variations in electrical properties induced by fluorination are characterized based on dielectric measurements. The experimental results show that chemical bonds are formed between nano-Al 2 O 3 and the coupling agent (KH550). Moreover, the results confirm that fluorination significantly alters the morphology and chemical structure of the sample surface. Gas-phase fluorination produces shallow traps, which consequently reduce the surface resistivity. The treatment of nano-Al 2 O 3 increases the trap energy level to yield higher surface resistivity. Furthermore, the treated Al 2 O 3 nanoparticles show improved distribution and dispersion in epoxy resin, exhibiting good dielectric performance of the nanocomposite.

Polyimide/mica hybrid films with low coefficient of thermal expansion and low dielectric constant

AbstractPolyimide (PI)/mica hybrid films were successfully prepared by in situ condensation polymerization method, in which the mica particles were modified by coupling agent γ-aminopropyltriethoxy silane (APTS) to strengthen the interaction between the mica particles and PI matrix. The morphology, structure, thermal and mechanical properties as well as dielectric properties of PI films were systematically studied via Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR spectrometer), Thermal gravimetric analysis (TGA), tensile experiments, Thermal mechanical analyzer (TMA), impedance analyzer, etc. The results indicated that the mica particles were dispersed homogeneously in PI matrix, leading to an improvement of the mechanical property, thermal stability and hydrophobicity. It was novel to notice that hybrid films exhibited low coefficient of thermal expansion (CTE) and low dielectric constant simultaneously. The CTE and dielectric constant of hybrid film dropped to 25.36 ppm/k and 2.42 respectively, in the presence of 10 wt% mica into polyimide matrix.

Coupling of synthesis and modification to produce hydrophobic or functionalized nano-silica particles

The processes of synthesis and surface modification were coupled herein to produce hydrophobic or functionalized nano-silica particles. Nano-silica particles with a spherical shape approximately 20 nm in diameter were synthesized. Nano-silica particles with high hydrophobicity were produced by coupling the synthesis with a modification process involving aqueous mixing, spray-drying, and thermal treatment, using the common surfactant sodium dodecyl sulfate (SDS) as a modifier. Amino-functionalized nano-silica particles with high grafting density were produced via the same process using the silane coupling agent γ-aminopropyltriethoxysilane (APTES). The modification was more effective with the coupled process than with the non-coupled process.

Derived from poplar leaves graphene-modified silicone rubber composites

Poplar leaves graphene (PLG) was synthesized from the poplar leaves. Modified poplar leaves graphene (M-PLG) was obtained by graphene treated with silane coupling agent γ-aminopropyltriethoxysilane (KH550). The M-PLG-modified silicone rubber (methyl ethylene silicon rubber [MVQ]) composites were prepared by mechanical blending. The effects of M-PLG on the mechanical properties, thermal properties, and morphology structure of MVQ were investigated. The results showed that the carbon content and purity of the PLG were high. The M-PLG can be evenly dispersed into MVQ compared with the PLG, the mechanical properties of the M-PLG/MVQ composites were better than those of the PLG/MVQ when M-PLG content was 0.1 parts per hundred rubber (phr), the tensile strength and elongation at break are increased by 36.2% and 19.4% respectively, and wear resistance increased by 57.1%. The thermal stability of the M-PLG/MVQ was also better. This concept of combining PLG with MVQ demonstrated the potential of preparing novel green materials with excellent properties.

Wear behavior of hollow glass beads (HGB) reinforced nitrile butadiene rubber: Effects of silane coupling agent and filler content

In this work, the hollow glass beads (HGB) reinforced nitrile butadiene rubber (NBR) were fabricated. Meanwhile, the influences of different silane coupling agent and HGB filler content on the mechanical and tribological performance under dry sliding condition are investigated. The characterization and experiment results revealed that the wear behavior of HGB/NBR composite was not only affected by the interfacial bonding strength between the HGB filler and the rubber matrix, but also restricted by the content of HGB filler. The NBR sample with HGB filler modified by 5 wt.% of silane coupling agent γ-aminopropyl triethoxysilane (KH550) showed good interfacial bonding strength and excellent wear resistance. Furthermore, the wear rate of HGB/NBR composite samples decreased with the increasing of the addition of 5 wt.% KH550 modified HGB filler.

Modified rapeseed oil/silane coupling agent-montmorillonite nanocomposites prepared by in-situ method: Synthesis and properties

The environmentally friendly flame retardant fatliquoring agent has aroused the attention of tannery industry. In this study, rapeseed oil and montmorillonite were used to prepare flame retardant fatliquoring agent. Firstly, silane coupling agent modified montmorillonite was prepared from Na-montmorillonite (Na-MMT) and silane coupling agent γ-aminopropyltriethoxysilane. Then the modified rapeseed oil/silane coupling agent modified montmorillonite nanocomposites was obtained by using silane coupling agent modified montmorillonite and rapeseed oil through in-situ method. The as-prepared modified rapeseed oil/silane coupling agent modified montmorillonite was applied in fatliquoring process of goatskin garment leather. Flame retardancy, softness and mechanical properties of the fatliquored leather were tested. Compared with those of the leather fatliquored by modified rapeseed oil (MRO), flame retardancy, softness and tear strength of the leather treated by modified rapeseed oil/silane coupling agent modified montmorillonite were improved. The results of environmental impact assessments indicated that the modified rapeseed oil/silane coupling agent modified montmorillonite nanocomposites did not increase the pollution to the environment.

Surface functionalized boehmite sheets filled epoxy composites with enhanced mechanical and thermal properties

Boehmite (AlOOH) sheets were synthesized via a hydrothermal method and then successfully functionalized with a bi-functional coupling agent, γ-aminopropyl- triethoxysilane (APTES), through a facile neutral solvent method. Scanning electron microscope and transmission electron microscopy images showed a uniform morphology of AlOOH sheets. APTES was found to be covalently bound with AlOOH sheets. The linked APTES can be combined with an epoxy oligomer through a ring opening addition reaction. The modified AlOOH was used as reinforcing agent to reinforce the epoxy resin cured by 4,4-diaminodiphenylsulfone. The results of tensile and differential scanning calorimetric test revealed the tensile strength and glass transition temperature (Tg) firstly increase and then decrease with the increase of functionalized AlOOH sheets loading. When the loading of functionalized AlOOH sheets increased to 5 parts per hundred resin, the highest tensile strength and Tg were obtained. They are 100.8 MPa and 174.5 °C. Microscopic examinations revealed the presence of large plastic deformations at the micronscale in the formed composites in agreement with the observed strengthening effect of functionalized AlOOH sheets. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of Modified Silica Abrasive Particles on Nanosized Particle Deposition in Final Polishing of Silicon Wafers

The silane coupling agent γ-aminopropyl triethoxysilane (APTS) and polyethylene oxide (PEO) are proposed to modify the SiO2 abrasive particles for final polishing of silicon wafers. The effects of the modified silica abrasive particles on nanosized particle deposition, roughness, and removal rate of the silicon wafer are explored in detail. PEO is proved to be a potential modifying agent for controlling deposition of large particles (∼410 nm diameter), leading to low roughness (Ra = 0.097 nm), and APTS is found to be effective in controlling deposition of both large and small particles (∼410 and ∼200 nm diameter, respectively), resulting in lower roughness (Ra = 0.054 nm).

Preparation of Silicone Modified Sulfonated Polyurethane/acrylic Composite Emulsion

A prepolymer was prepared by reacting the obtained sulfonated polyester polyol with isophorone diisocyanate(IPDI) and trimethylolpropane(TMP).The seed emulsion containing viny and silicone was prepared by end-capping with bifunctional monomer β-hydroxyethyl methacrylate(HEMA) and modification by silane coupling agent γ-aminopropyl triethoxysilane(KH550).The silicone modified sulfonated polyurethane/acrylic composite emulsion was obtained by mixing methyl methacrylate(MMA) and butyl acrylate(BA) monomers.The silicone modified sulfonated polyurethane/acrylic composite emulsion was characterized by infrared spectroscopy.The core-shell structure of the composite emulsion was confirmed by the transmission electron microscopy.Thermogravimetric analysis showed that an increase of 20 ℃ of the largest thermal mass loss temperature could be observed for the organic silicon and acrylic modified films.Meanwhile,the crystallinity was decreased as revealed by X-ray diffraction result,which could help to improve the toughness of the film.In addition,when the organic silicon content is 1.9%,the tensile strength of the film is up to 25.03 MPa,its elongation at break is 328%,and has the lowest water absorption.

Ultra low dielectric constant hybrid films via side chain grafting reaction of poly(ether ether ketone) and phosphotungstic acid

The novel ultra low dielectric constant poly(ether ether ketone) hybrid films in which nanoscale phosphotungstic acid (PWA) clusters were grafted onto the side chains of poly(ether ether ketone) containing (3-trifluoromethyl) phenyl groups and carboxyl groups (PEEK–CF3–COOH) in the presence the silane coupling agent γ-aminopropyltriethoxysilane (KH-550) were prepared and characterized. The chemical structures of the PWA/PEEK–CF3–COOH hybrid films were confirmed by FT-IR spectroscopy and 1H-NMR. The analysis of wide-angle X-ray diffraction (WAXD) indicated that the PWA clusters could not form crystalline structures in the PEEK–CF3–COOH matrix, and the investigation of the scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) (W-mapping) revealed that the PWA particles were well dispersed in the PEEK–CF3–COOH matrix with nanoscale. The influence of the incorporation of PWA particles by side chain grafting reaction on the properties of PEEK–CF3–COOH was studied. The dielectric constants of the PWA/PEEK–CF3–COOH hybrid films were remarkably lower than that of the neat PEEK–CF3–COOH film and the lowest value their dielectric constant could achieve was as low as 1.96 (1 MHz) when the content of grafted PWA reached 10 wt%. Meanwhile, the hybrid films still retain the excellent thermal and mechanical properties as well as the good transparency.

Recycling of Thermosetting Epoxy Molding Compound Waste into PVC Composites: Effect of Silane Coupling Agent on Morphology and Physical Properties

The aim of this study was to investigate the recycling of waste cured epoxy molding compound (c-EMC) which was generated as the mold residue in molding process of electronic component packages, by way of blending the pulverized mold residue with poly (vinyl chloride) (PVC) and other additives to prepare a reproduction composite. The influence of modified and non-modified c-EMC powder on structure and properties of the composites were analyzed by mechanical tests, vicat softening point test (VST) and scanning electron microscopy (SEM). The results showed that simple adding c-EMC powder could improve the stiffness and heat resistance of the composites, though decreased the mechanical strength of the composites. After being pretreated by silane coupling agent γ-aminopropyltriethoxysilane (KH-550), modified c-EMC powder had effective strengthening and toughening effects on the composites with the increasing powder content. Furthermore, better interfacial adhesion and higher VST value of the composites were observed in the presence of KH-550.

Acid–base interactions and covalent bonding at a fiber–matrix interface: contribution to the work of adhesion and measured adhesion strength

The work of adhesion, W A, and the practical adhesion in terms of the interfacial shear strength, τ, in some polymer-fiber systems were determined to establish a correlation between these quantities. An attempt was made to analyze the contributions of various interfacial interactions (van der Waals forces, acid-base interaction, covalent bonding) to the 'fundamental' and 'practical' adhesion. The surface free energies of the fibers were altered using different coupling agents. To characterize the strength of an adhesion contact, the ultimate adhesion strength, τult, was determined for the onset of contact failure. The adhesion of non-polar polymers occurs through van der Waals interaction only; therefore, fiber sizing does not affect the adhesion strength. For polar polymers, such as poly(acrylonitrile butadiene styrene) and polystyrene, adhesion is sensitive to fiber treatments: suppression of the acid-base interaction by using an electron-donor sizing agent γ-aminopropyltriethoxysilane results in a decrease of both 'fundamental' and 'practical' adhesion. In the case of epoxy resins, the main contribution to the work of adhesion is made by covalent bonds. Since the process of their formation is irreversible, the work of adhesion determined from micromechanical tests seems to be more reliable than indirect estimations, such as from wetting and inverse gas chromatography techniques. Fiber treatment by sizing agents results in considerable changes in the intensity of adhesional interaction with the epoxy matrix. A correlation between the work of adhesion, the ultimate interfacial shear strength, and the strength of macro-composites has been found.

Interfacial mobility and its effect on interlaminar fracture toughness in glass-fibre-reinforced epoxy laminates

The effects of interfacial treatment of glass fibres in glass/epoxy composites were studied through Mode I delamination fracture toughness tests using a double cantilever beam specimen. The treatment of glass fibres with two similar silane coupling agents has been shown to improve the mechanical properties of the composite as a function of the type of coupling agent, γ-aminopropyltriethoxysilane (APS) and γ-aminobutyltriethoxysilane (ABS) have similar chemistry, but differ in mobility (molecular motion) at the coupling agent-epoxy interface. The critical energy release rate, G 1c, for the APS-treated composites (0.59±0.05 kJ m−2) was shown to be higher than that of the ABS-treated one (0.37±0.01 kJ m−2) and also the untreated one (0.31±0.02 kJ m−2). In this case, the bulk structural property appears to be a function of the microscopic interfacial properties including the dynamics of the coupling agent layer. Optical characterization of the fracture surfaces reveal delamination at the epoxy-glass interface for the untreated samples, while the ABS- and APS-treated samples showed less interfacial delamination, respectively.

Reactive processing of polymer blends: Analysis of the change in morphological and interfacial parameters with processing

AbstractThe change in morphology and interface quantities have been analyzed for an immiscible polymer blend during reactive processing. A model polymer/polymer combination, hydroxy‐terminated poly(ε‐caprolactone)/liquid rubber with α, ω‐carboxy groups, was employed. The blend was subjected to light scattering measurements, ellipsometry, and gel permeation chromatography (GPC). Size reduction of the dispersed phase during processing was followed by a systematic decrease in the correlation distance ζ and an increase in the specific interfacial area Ssp, both by the Debye‐Bueche plot of light scattering profiles. Also observed was the time variation of the volume fraction of interface Vλ estimated as a product of the Ssp and the interfacial thickness by ellipsometry. The changes in ζ, Ssp, and Vλ with processing were accelerated when a coupling agent,γ‐aminopropyltriethoxysilane (APS), was added. The amount of block copolymer formed in‐situ in the APS‐loaded system was estimated by GPC with RI and UV detectors. For the size reduction kinetics in both APS‐loaded and ‐unloaded systems, Rittinger's law was found to be applicable.

Applications of Diffuse Reflectance FT-IR to the Characterization of an E-Glass Fiber/γ-APS Coupling Agent System

The utility of diffuse reflectance FT-IR (DRIFT) spectroscopy is explored to study the surfaces of clean E-glass fibers and E-glass/coupling agent systems. The ability to use a nondestructive sampling procedure is an important benefit for the study of these systems. However, the nature of the fiber samples leads to several experimental difficulties. We solve these problems through the use of a KBr overlayer. Using this sample-preparation procedure, we increase the information derivable from the spectra. The inherent surface sensitivity of the DRIFT technique is demonstrated by the study of small amounts of the silane coupling agent γ-aminopropyltriethoxysilane (γ-APS) on the surface of E-glass fibers.