3-glycidyloxypropyl Trimethoxysilane Research Articles

The Role of Surface Treatment and Coupling Agents for Adhesion between Stainless Steel (SUS) and Polyamide (PA) of Heterojunction Bilayer Composites.

The growing demand for lightweight and durable materials in industries, such as the automotive, aerospace, and electronics industries, has spurred the development of heterojunction bilayer composites, combining the structural integrity of metals with the versatility of polymers. This study addresses the critical interface between stainless steel (SUS) and polyamide 66 (PA66), focusing on the pivotal role of surface treatments and various silane coupling agents in enhancing the adhesion strength of heterojunction SUS/PA66 bilayer composites. Through systematic surface modifications-highlighted by scanning electron microscopy, atomic force microscopy, and contact angle analyses-the study assessed the impact of increasing the surface area, roughness, and energy of SUS. X-ray photoelectron spectroscopy evaluations confirmed the strategic selection of specific silane coupling agents. Although some coupling agents barely influenced the mechanics, notably, aminopropyl triethoxysilane (A1S) and 3-glycidyl oxypropyl trimethoxysilane (ES) significantly enhanced the mechanical properties of the heterojunction bilayer composites, evidenced by the improved lap shear strength, elongation at break, and toughness. These advancements were attributed to the interfacial interactions at the metal-polymer interface. This research underscored the significance of targeted surface treatment and the judicious selection of coupling agents in optimizing the interfacial adhesion and overall performance of metal-polymer composites, offering valuable insights for the fabrication of materials where reduced weight and enhanced durability are paramount.

Additive Blending Effects on PEDOT:PSS Composite Films for Wearable Organic Electrochemical Transistors.

Organic electrochemical transistors (OECTs) employing conductive polymers (CPs) have gained remarkable prominence and have undergone extensive advancements in wearable and implantable bioelectronic applications in recent years. Among the diverse arrays of CPs, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a common choice for the active-layer channel in p-type OECTs, showing a remarkably high transconductance for the high amplification of signals in biosensing applications. This investigation focuses on the novel engineering of PEDOT:PSS composite materials by seamlessly integrating several additives, namely, dimethyl sulfoxide (DMSO), (3-glycidyloxypropyl)trimethoxysilane (GOPS), and a nonionic fluorosurfactant (NIFS), to fine-tune their electrical conductivity, self-healing capability, and stretchability. To elucidate the intricate influences of the DMSO, GOPS, and NIFS additives on the formation of PEDOT:PSS composite films, theoretical calculations were performed, encompassing the solubility parameters and surface energies of the constituent components of the NIFS, PEDOT, PSS, and PSS-GOPS polymers. Furthermore, we conducted a comprehensive array of material analyses, which reveal the intricacies of the phase separation phenomenon and its interaction with the materials' characteristics. Our research identified the optimal composition for the PEDOT:PSS composite films, characterized by outstanding self-healing and stretchable capabilities. This composition has proven to be highly effective for constructing an active-layer channel in the form of OECT-based biosensors fabricated onto polydimethylsiloxane substrates for detecting dopamine. Overall, these findings represent significant progress in the application of PEDOT:PSS composite films in wearable bioelectronics and pave the way for the development of state-of-the-art biosensing technologies.

Improvement of tensile strength and toughness in aramid/epoxy composites by sequential air plasma and (3-glycidyloxypropyl) trimethoxysilane treatments

This work explores sequential surface treatments involving atmospheric-air plasma and (3-glycidyloxypropyl) trimethoxysilane (GLYMO) to enhance the tensile properties of aramid/epoxy composites. To prove the technical advantages of this approach, aramid fibers received individual (atmospheric-air plasma or GLYMO) or sequential (plasma followed by GLYMO, and vice versa) surface treatments. Single fiber tensile tests (SFT) and X-ray photoelectron spectroscopy (XPS) were employed to characterize changes in aramid fibers upon the surface modifications. SFT revealed that none of the surface treatments compromised their tensile strength (σ max ). Applying GLYMO, whether individually or in sequence (GLYMO followed by plasma and plasma followed by GLYMO), led to a significant enhancement in the fibers’ elastic modulus (E). Composites with plasma-treated fibers displayed a 5% increase in E and an 8.5% increase in σ max , with no changes in toughness. However, the most notable improvements were achieved through sequential plasma followed by GLYMO treatments, resulting in a ~ 10% increase in σ max and a remarkable ~ 40% improvement in toughness. Plasma introduces oxygen-containing groups to the fiber surface, facilitating GLYMO grafting. Subsequent crosslinking of GLYMO with the epoxy resin strengthens the fiber-matrix interface. This sequential surface modification offers an alternative pathway for fabricating composites with superior toughness and σ max .

Investigating the role of silane treatment in enhancing the anti-corrosion properties of MoS2 particle-embedded epoxy coatings on steel

In the present study, chemical surface treatment was performed on Molybdenum (IV) disulfide (MoS2) nanoparticles with two coupling agents; amino silane ((3-Aminopropyl) triethoxysilane) and epoxy silane ((3-Glycidyloxypropyl) trimethoxysilane), and the effect of these nanoparticle embedment into epoxy coating was evaluated. Chemical structure of the nanoparticles was confirmed by Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) confirms that 21 wt% of surface-treated MoS2 nanoparticles (MoS2 + AS) is amino silane, but the surface treatment with epoxy silane has not been very effective. The morphology and physical structure of nanoparticles were evaluated by Field emission scanning electron microscopy (FE-SEM) and X-Ray diffraction analysis (XRD), which respectively shows that the surface treatment with epoxy silane cannot interfere the agglomeration of MoS2 nanosheets. The exceptional corrosion resistance of the coating containing 2 wt% of MoS2 + AS nanoparticles has been verified using both EIS and salt spray measurements. Furthermore, it is anticipated that this remarkable performance will endure over time, as there was no substantial decline in the corrosion resistance of the coating even after duration of 21 days with a recorded Rp value of 1.19 × 108 Ω·cm2.

MECHANICAL STIMULATION OF PIEZOELECTRIC SCAFFOLDS PROMOTES CELL OSTEOGENIC DIFFERENTIATION

Bone is a dynamic tissue that undergoes continuous mechanical forces. Mechanical stimuli applied on scaffolds resembling a part of the human bone tissue affects the osteogenesis [1]. Poly(3,4-ethylenedioxythiophene) (PEDOT) is a piezoelectric material that responds to mechanical stimulation producing an electrical signal, which in turn promotes the osteogenic differentiation of bone-forming cells by opening voltage-gated calcium channels [2]. In this study we examined the biological behavior of pre-osteoblastic cells seeded onto lyophilized piezoelectric PEDOT-containing scaffolds applying uniaxial compression.Two different concentrations of PEDOT (0.10 and 0.15% w/v) were combined with a 5% w/v poly(vinyl alcohol) (PVA) and 5% w/v gelatin, casted into wells, freeze dried and crosslinked with 2% v/v (3-glycidyloxypropyl)trimethoxysilane and 0.025% w/v glutaraldehyde. The scaffolds were physicochemically characterized by FTIR, measurement of the elastic modulus, swelling ratio and degradation rate. The cell-loaded scaffolds were subjected to uniaxial compression with a frequency of 1 Hz and a strain of 10% for 1 h every second day for 21 days. The loading parameters were selected to resemble the in vivo loading situation [3]. Cell viability and morphology on the PEDOT/PVA/gelatin scaffolds was determined. The alkaline phosphatase (ALP) activity, the collagen and calcium production were determined.The elastic modulus of PEDOT/PVA/gelatin scaffolds ranged between 1 and 5 MPa. The degradation rate indicates a mass loss of 15% after 21 days. The cell viability assessment displays excellent biocompatibility, while SEM images display well-spread cells. The ALP activity at days 3, 7 and 18 as well as the calcium production are higher in the dynamic culture compared to the static one. Moreover, energy dispersive spectroscopy analysis revealed the presence of calcium phosphate in the extracellular matrix after 14 days. The results demonstrate that PEDOT/PVA/gelatin scaffolds promote the adhesion, proliferation, and osteogenic differentiation of pre-osteoblastic cells under mechanical stimulation, thus favoring bone regeneration.

Embedding anatase, rutile, and brookite TiO2 nanoparticles to cotton fabric with epoxy silane and comparison of their effects on photodegradation

Purpose This study aims to embed anatase, rutile and brookite TiO2 nanoparticles (NPs) with different crystal phases into cotton fabrics by epoxy silane and to examine the effect of these applications on the photocatalytic and mechanical properties of the fabric. Design/methodology/approach Different aqueous dispersions which contain anatase, rutile and brookite were prepared at three different concentrations (5%, 10% and 15%). These NPs were embedded in cotton fabrics by using GPTS [(3-glycidyloxypropyl) trimethoxysilane]. Characterization tests were performed by scanning electron microscopy (SEM), Raman and Fourier-transform infrared spectroscopy (FT/IR). Samples were stained with methylene blue (MB) and then exposed to solar light for different periods. Color changes of the samples were examined with a spectrophotometer. Air permeability, abrasion and tear strength tests were applied to all samples. Findings According to SEM images, the NPs were successfully attached to the cotton fabrics, and epoxy silane coating surrounded the fiber surfaces. The presence of the coating was also confirmed by Raman spectroscopy and FT/IR. The treatments reduced the stainability of the samples. The most effective applications for ensuring photocatalytic activity in cotton fabrics were suspensions as 10% brookite, 10% anatase and 5% anatase, in descending order. The applied coating slightly reduced the samples’ air permeability, and wear and tear strength. Originality/value The importance of this study is to determine the optimal crystal phase and its concentration by using epoxy silane to ensure self-cleaning properties on cotton fabrics. The sample treated with 10% brookite is the most approached its original white color by 99.65% as a result of degradation of MB (after 120 min). On the other hand, using the pure rutile with epoxy silane was not suitable for removing MB from the fabric.

Functionalization of Phosphate and Tellurite Glasses and Spherical Whispering Gallery Mode Microresonators.

Active whispering gallery mode resonators made as spherical microspheres doped with quantum dots or rare earth ions achieve high quality factors and are excellent candidates for biosensors capable of detecting biomolecules at low concentrations. However, to produce quantum dot-doped microspheres, new low melting temperature glasses are sought, which require surface functionalization and antibody immobilization for biosensor development. Here, we demonstrate the successful functionalization of three low melting point glasses and microspheres made of them. The glasses were made from sodium borophosphate, sodium aluminophosphate, and tellurite, and then, they were functionalized using (3-glycidyloxypropyl)trimethoxysilane in ethanol- and toluene-based protocols. Proper silanization was confirmed by energy-dispersive X-ray spectroscopy and fluorescence microscopy of an amino-modified luminescent oligonucleotide probe. Fluorescence imaging showed successful silanization for all tested samples and no degradation for aluminophosphate and tellurite glasses. The strongest signal was registered for tellurite glass samples functionalized using the toluene-based silanization protocol. This conclusion implies that this functionalization method is the most efficient and is highly recommended for future antibody immobilization and biosensing application.

Guar gum/poly ethylene glycol/graphene oxide environmentally friendly hybrid hydrogels for controlled release of boron micronutrient.

The present study was aimed at synthesis of polymeric hydrogels for controlled boron (B) release, as B deficiency is a major factor that decreases crops yield. Thus, graphene oxide incorporated guar gum and poly (ethylene glycol) hydrogels were prepared using the Solution Casting method for boron release. 3-Glycidyloxypropyl trimethoxysilane (GLYMOL) was used as a cross-linker. Characterizations of hydrogels were carried out by Fourier Transform Infrared Spectroscopy (FTIR), Thermo-Gravimetric Analysis and Scanning Electron scope. The FTIR outcomes confirmed the existence of functional groups, bindings and development of hydrogel frameworks from incorporated components. The quantity of GLYMOL directly increased the thermal stability and water retention but decreased the swelling %. The maximum swelling for the hydrogel formulations was observed at pH 7. The addition of GLYMOL changed the diffusion from quasi-Fickcian to non-Fickcian diffusion. The maximum swelling quantities of 3822% and 3342% were exhibited by GPP (control) and GPP-8 in distilled water, respectively. Boron release was determined in distilled water and sandy soil by azomethine-H test using UV-Visible spectrophotometer while 85.11% and 73.65% boron was released from BGPP-16, respectively. In short, water retentive, water holding capacities, swelling performances, biodegradability and swelling/deswelling features would offer an ideal platform for boron release in sustained agricultural applications.

Graphene with different groups on the interfacial properties of carbon fiber/epoxy composites

To achieve better interfacial adherence of carbon fibers to the epoxy resin, the graphene modified with ammonia and 3-Glycidyloxypropyl trimethoxysilane (GPTMS) was utilized to modify the epoxy resin. Subsequently, a simple two-step method of wet impregnation and the thermoforming process was employed to fabricate the CF/graphene-modified epoxy (CF/EG/EP) composites. The interfacial properties of CF/EP composites were studied using microdroplet debonding and short-beam shear tests on modified graphene (MEG). It is shown that the incorporation of GPTMS-modified graphene into the CF/EP composites strengthened the interfacial and bending properties of CF and matrix, resulting in a 12.5 % growth in interlaminar shear strength (ILSS) and 22.5 % growth in flexural strength of the CF/EP composites, respectively. Meanwhile, scanning electron microscope images confirmed the effectiveness of the GPTMS-modified graphene in improving the interfacial compatibility and adhesion of CF/EP composites.

Surface Functionalization with (3-Glycidyloxypropyl)trimethoxysilane (GOPS) as an Alternative to Blending for Enhancing the Aqueous Stability and Electronic Performance of PEDOT:PSS Thin Films.

Organic mixed ionic-electronic conductors, such as poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), are essential materials for the fabrication of bioelectronic devices due to their unique ability to couple and transport ionic and electronic charges. The growing interest in bioelectronic devices has led to the development of organic electrochemical transistors (OECTs) that can operate in aqueous solutions and transduce ionic signals of biological origin into measurable electronic signals. A common challenge with OECTs is maintaining the stability and performance of the PEDOT:PSS films operating under aqueous conditions. Although the conventional approach of blending the PEDOT:PSS dispersions with a cross-linker such as (3-glycidyloxypropyl)trimethoxysilane (GOPS) helps to ensure strong adhesion of the films to device substrates, it also impacts the morphology and thus electrical properties of the PEDOT:PSS films, which leads to a significant reduction in the performance of OECTs. In this study, we instead functionalize only the surface of the device substrates with GOPS to introduce a silane monolayer before spin-coating the PEDOT:PSS dispersion on the substrate. In all cases, having a GOPS monolayer instead of a blend leads to increased electronic performance metrics, such as three times higher electronic conductivity, volumetric capacitance, and mobility-capacitance product [μC*] value in OECT devices, ultimately leading to a record value of 406 ± 39 F cm-1 V-1 s-1 for amorphous PEDOT:PSS. This increased performance does not come at the expense of operational stability, as both the blend and surface functionalization show similar performance when subjected to pulsed gate bias stress, long-term electrochemical cycling tests, and aging over 150 days. Overall, this study establishes a novel approach to using GOPS as a surface monolayer instead of a blended cross-linker, for achieving high-performance organic mixed ionic-electronic conductors that are stable in water for bioelectronics.

Preparation of transparent hard GPTMS-Al2O3 thin films on a polycarbonate substrate

Using polycarbonate (PC) due to its incredible properties as a suitable replacement for inorganic glasses has been increasing. Nevertheless, the low hardness limits its applications in more industries. Hence, it requires to be coated with hard anti-scratch optical coatings to overcome these limitations. In the current work, sol-gel-prepared thin films based on (3-Glycidyloxypropyl) trimethoxysilane (GPTMS)-Al2O3 were applied on PC substrates. First, silica and alumina sols were synthesized by a sol-gel process, individually. Then, the prepared sols were mixed at different ratios and dip-coated on the plasma etched pretreatment PC substrates. Curing of the samples was done in an oven at 100 °C. The produced thin films were characterized by field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Attenuated total reflectance -Fourier transform infrared spectroscopy (ATR-FTIR), and UV/Vis spectroscopy techniques. The obtained results indicated that the PC hardness increased from 6B to H by deposition of nano-hybrid coatings. After applying a nano-hybrid coating, transmittance was increased from 88 % to 91 % and the reflectance decreased from 10 % to 5 %. Sample with a 1:4 GPTMS-Al2O3 ratio showed the best results.

Metal Oxide Nanostructures Enhanced Microfluidic Platform for Efficient and Sensitive Immunofluorescence Detection of Dengue Virus.

Rapid and sensitive detection of Dengue virus remains a critical challenge in global public health. This study presents the development and evaluation of a Zinc Oxide nanorod (ZnO NR)-surface-integrated microfluidic platform for the early detection of Dengue virus. Utilizing a seed-assisted hydrothermal synthesis method, high-purity ZnO NRs were synthesized, characterized by their hexagonal wurtzite structure and a high surface-to-volume ratio, offering abundant binding sites for bioconjugation. Further, a comparative analysis demonstrated that the ZnO NR substrate outperformed traditional bare glass substrates in functionalization efficiency with 4G2 monoclonal antibody (mAb). Subsequent optimization of the functionalization process identified 4% (3-Glycidyloxypropyl)trimethoxysilane (GPTMS) as the most effective surface modifier. The integration of this substrate within a herringbone-structured microfluidic platform resulted in a robust device for immunofluorescence detection of DENV-3. The limit of detection (LOD) for DENV-3 was observed to be as low as 3.1 × 10-4 ng/mL, highlighting the remarkable sensitivity of the ZnO NR-integrated microfluidic device. This study emphasizes the potential of ZnO NRs and the developed microfluidic platform for the early detection of DENV-3, with possible expansion to other biological targets, hence paving the way for enhanced public health responses and improved disease management strategies.

Surface-Modified Electrospun Glass Nanofibers from Silane Treatment and Their Use for High-Performance Epoxy-Based Nanocomposite Materials.

As a new and promising reinforcing filler, electrospun glass nanofibers (EGNFs) have attracted attention in the field of polymer composite materials. However, the reinforcing effectiveness of surface-modified EGNFs using different silane coupling agents in epoxy resin is still not quite clear. In this research, a series of silane coupling agents with increasing chain lengths in the order of methyl trimethoxysilane (MTMS), (3-aminopropyl) triethoxysilane (APTES), (3-glycidyloxypropyl) trimethoxysilane (GPTMS), and dual silane coupling agent APTES-GPTMS were employed to carry out surface treatment on the EGNFs. The pristine and silane functionalized EGNFs were then incorporated into epoxy resin as reinforcing fillers at low loading levels, i.e., 0.25 wt.%, 0.5 wt.%, and 1 wt.%, and the mechanical properties of the resultant epoxy nanocomposites, including strength, stiffness, ductility, and toughness, were evaluated. A commercial product of glass nanoparticles (GNPs) was used as a control to compare the reinforcing effectiveness of the EGNFs and the GNPs. This study revealed that the EGNFs could provide significant reinforcing and toughening effects at ultra-low loading (0.25 wt.%) in epoxy nanocomposite materials. Furthermore, surface modification of the EGNFs with silane coupling agents with long chain lengths, e.g., by using dual silane coupling agents, APTES-GPTMS, could enhance the interfacial bonding between the EGNFs and the epoxy matrix and further increase the mechanical performance of the EGNF-reinforced epoxy nanocomposite materials. Through this research, we realized epoxy nanocomposite materials with much-improved mechanical properties, i.e., 37%, 24%, 18%, 57% improvement in strength, stiffness, ductility, and toughness, respectively, with respect to those of the cured neat epoxy material with an ultra-low loading (0.25 wt.%) of APTES-GPTMS-EGNFs. Our research paves the road for developing lighter and stronger epoxy nanocomposite materials with EGNFs.

Epoxy-thiol crosslinking for enhanced mechanical strength in silica aerogels and highly efficient dye adsorption

Epoxy-thiol crosslinked silica aerogels were synthesized with (3-glycidyloxypropyl)trimethoxysilane and (3-mercaptopropyl)trimethoxysilane as co-precursors in acid and base catalyzed reactions via in situ epoxy-thiol click polymerization followed by hydrolysis and condensation using tetraethylorthosilicate (TEOS) as a primary precursor. The acid and base-catalyzed aerogels were prepared by varying the TEOS and tetramethylammonium hydroxide mole ratios, while maintaining all other formulations with a constant molar ratio. The acid-catalyzed silica aerogel (TGM) had a notable specific surface area (297 m2/g) and compressive modulus ∼8.5 MPa, whereas the hybrid base-catalyzed silica aerogel (BTGM) appeared to have a relatively high specific surface area (519 m2/g) than the TGM aerogel. In particular, the robustness of BTGM aerogels exhibited a significantly enhanced compressive modulus (11 MPa), and the obtained thermal conductivity was 0.047–0.050 W.m−1.K−1, which was comparable to that of TGM-based aerogels, owing to methoxy groups being hydrolyzed at different rates. The maximum adsorption capabilities for the removal of methylene blue dye, as measured using the Langmuir adsorption model, were 1694.9 mg/g. The isotherm and adsorption kinetics both adhered to Langmuir and pseudo-second order models, respectively. The proposed approach serves as a new strategy for in situ epoxy-thiol click polymerization-based silica aerogels with improved mechanical resilience for pollutant adsorption.

Chemical vapour deposition in narrow capillaries: Electro-osmotic flow control in capillary electrophoresis

BackgroundIn capillary electrophoresis (CE), the inner surface of fused-silica capillaries is commonly covalently modified with liquid silanes to control electroosmotic flow (EOF). This liquid phase deposition (LPD) approach is challenging for long and narrow-diameter capillaries (≥1 m, ≤25 μm ID) inhibiting commercial production. Here, we use chemical vapour deposition (CVD) to covalently modify capillaries with different silanes. Using a home-built CVD device, capillaries were modified with neutral (3-glycidyloxypropyl) trimethoxysilane (GPTMS), the weak base (3-aminopropyl) trimethoxysilane (APTMS), the weak acid 3-mercaptopropyltrimethoxysilane (MPTMS) and the neutral hydrophobic trichloro(1H,1H,2H,2H-perfluorooctyl) silane (PFOCTS). Gas-phase modification of GPTMS with acid and ammonia allowed further modification of the surface prior to molecular layer deposition (MLD) of poly(p-phenylene terephthalamide) (PPTA) using the self-limiting sequential reaction between terephthalaldehyde (TA) and p-phenylenediamine (PD) vapours. ResultsCapillaries coated with GPTMS by CVD showed a greater reduction in EOF at all pH values than the conventional LPD. APTMS showed a reduction of the EOF at pH 9, with EOF reversal observed below pH 6. MPTMS provided a slightly lower EOF than an unmodified capillary at high pH, and a slightly higher EOF at lower pH. PFOCTS provided the most consistent EOF as a function of pH. The deposition of successive layers of PPTA resulted in increased surface coverage of the polymer and a greater reduction in EOF at pH higher than 5. The stability of a 10 μm ID GPTMS coated capillary was tested at pH 8.8 in a 200 mM CHES/Tris BGE for the separation of inorganic anions. Over 1.5 months of continuous operation (≈4130 runs), the reproducibility of the apparent mobilities for chloride, nitrite, nitrate and sulfate were 2.43%, 2.56%, 2.63% and 3.05%, respectively. The intra-day and inter-day column-to-column reproducibility and batch-to-batch reproducibility for all the coated capillaries ranged between 0.34% and 3.95%. SignificanceThe study demonstrates the superior performance of CVD coating for suppressing the EOF compared to LPD allowing the easy modification of long lengths of narrow capillary. The variation in silane, and the ability of MLD to modify and control the surface chemistry, provides a simple and facile method for surface modification. The stability of these coatings will allow long-term capillary electrophoresis monitoring of water chemistry, such as for monitoring fertiliser run-off in natural waters.

Photoluminescence properties of Lu2Si2O7:Eu3+ sol-gel thin films obtained using GLYMO as a silicon source

Thin films of Lu2Si2O7:Eu3+ were prepared via sol-gel methods and dip coating using lutetium nitrate and (3-Glycidyloxypropyl)trimethoxysilane as precursors, and ethanol and ethylene glycol were used as solvents. Acetylacetone was used as a stabilizer, and the pH was adjusted using acetic acid. Lu2Si2O7:Eu3+ films were deposited on silica quartz substrates and exhibited a monoclinic structure with preferential orientation along the [012] direction after heat treatment at 1000 °C. The film’ morphology was characterized by scanning electron microscopy, and the photoluminescence spectrum revealed a strong emission at 612 nm (5D0→7F2), corresponding to the Eu3+ ions, under 254 nm excitation. Notably, both the optical yield and decay time increased with increasing SiO2 content.

Bio-based hybrid nanocomposites as multifunctional sustainable materials for stone conservation

This study was aimed at developing a sustainable versatile bio-based epoxy-silica material to be potentially employed as hydrophobic and biocidal consolidating product in the field of stone conservation. For this purpose, two hybrid formulations containing 2,2,4,4-tetramethyl-1,3-cyclobutanediol diglycidylether (CBDO-DGE), a cycloaliphatic epoxy precursor derived from the arnica root, together with (3-glycidyloxypropyl)trimethoxysilane (GPTMS) and octyltriethoxysilane (OcTES) as silica-forming additives, were chosen as the basis of the multifunctional material to be finely adjusted and gain biocidal properties. With this goal in mind, different synthetic strategies based on ionic liquids (ILs), essential oils (EOs) and nanoparticles (NPs) doping have been employed. Specifically, dimethyloctadecyl[3(trimethoxysilyl)propyl]ammonium chloride (QAS), tetradecyl phosphonium chloride (QPS) and thymol, as well as cerium-TiO2 NPs and thymol-loaded SiO2 NPs were incorporated into the starting hybrid formulations, during the sol-gel process, to investigate their influence on the network formation. First, distribution studies by scanning electron microscopy/energy-dispersive X-ray (SEM-EDS) analysis were performed, whereas the suitability of each formulation to match the main requirements for a stone conservation material was evaluated in terms of thermostability, hydrophobicity and inhibition of the microbiological growth by a combination of TG-DTA, DSC, dynamic mechanical analysis (DMA), with contact angle and disk-diffusion measurements, respectively. Based on the data analysis, it was observed that the direct incorporation of ILs and EOs had an adverse effect on the ability of GPTMS to act as a coupling agent. This resulted in decreased thermal stability and a 50 % reduction in glass transition temperatures, along with the retention of hydrophilic behavior. In contrast, the inclusion of NPs did not significantly interfere with the hybrid network formation, and effectively maintained the thermo-mechanical and hydrophobic properties of the hybrids within satisfactory parameters. Consequently, both nanocomposite materials were further tested on stone samples by artificial ageing experiments under acidic atmosphere. In view of the results, the hybrid enriched with thymol-loaded SiO2 NPs demonstrate the most suitable thermo-mechanical and hydrophobic properties (Tonset, Tα and CA values of 276 °C, 54 °C and 100°, respectively), as well as a proper biocidal capability against bacteria. Furthermore, the developed material provided effective stone protection, resulting in a 92 % reduction in material loss, while preserving the substrate chromatic characteristics (ΔE 2.23). These findings suggest that the proposed treatment meets the first main requirements for stone conservation.

One-Pot Sol-Gel Synthesis of Highly Insulative Hybrid P(AAm-CO-AAc)-Silica Aerogels with Improved Mechanical and Thermal Properties.

Silica aerogels and their derivatives have outstanding thermal properties with exceptional values in the thermal insulation industry. However, their brittle nature restricts their large-scale commercialization. Thus, enhancing their mechanical strength without affecting their thermal insulating properties is essential. Therefore, for the first time, highly thermally stable poly(acrylamide-co-acrylic acid) partial sodium salt is used as a reinforcing polymer to synthesize hybrid P(AAm-CO-AAc)-silica aerogels via epoxy ring-opening polymerization in the present study. Functional groups in P(AAm-CO-AAc) partial sodium salts, such as CONH2 and COOH, acted as nucleophiles for the epoxy ring-opening reaction with (3-glycidyloxypropyl)trimethoxysilane, which resulted in a seven-fold enhancement in mechanical strength compared to that of pristine silica aerogel while maintaining thermal conductivity at less than 30.6 mW/mK and porosity of more than 93.68%. Moreover, the hybrid P(AAm-CO-AAc)-silica aerogel demonstrated improved thermal stability up to 343 °C, owing to the synergetic effect between the P(AAm-CO-AAc) and the silica aerogel, corresponding to the thermal stability and strong covalent bonding among them. These excellent results illustrate that this new synthetic approach for producing hybrid P(AAm-CO-AAc)-silica aerogels is useful for enhancing the mechanical strength of pristine silica aerogel without impairing its thermal insulating property and shows potential as an industrial heat insulation material.

Guar gum-based stimuli responsive hydrogels for sustained release of diclofenac sodium

In the current study, hydrogels for the controlled release of diclofenac sodium were synthesized from graphene oxide-reinforced guar gum and poly (N-vinyl-2-pyrrolidone) using the Solution Casting Technique. Varying concentrations of 3-Glycidyloxypropyl trimethoxysilane (GLYMO) were employed for the crosslinking of hydrogels. Further, the characterization of hydrogels was carried out using different techniques such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction, thermal analysis and scanning electron microscope. The FTIR investigations reveals particular functionalities and development of hydrogel interfaces. While thermal analysis prophesied that, improvement in forces among hydrogel components is directly proportional to the GLYMO concentration. In-vitro biodegradation test and cell viability assay against HEK-293 cell lines confirmed their biodegradable and biocompatible nature. GPG-32 demonstrated maximum antibacterial activity against P.aeruginosa and E.coli strains. The maximum swelling 2001 % and 1814 % in distilled water were recorded for GPG (control) and GPG-8 respectively that obeyed Fick's law. Hydrogels displayed high swelling responses at pH 6 in buffer and non-buffer solutions. In 2.5 h, 88.7 % diclofenac sodium was released which was determined by UV visible spectrophotometer. In conclusion, guar gum-based non-toxic, biocompatible and biodegradable hydrogels would be a model platform for targeting inflammation and pains. Furthermore, improved mechanical and viscoelastic behavior of hydrogels could also be explored for making drug loaded dressings for wound healing applications.

Biophysical Electrical and Mechanical Stimulations for Promoting Chondrogenesis of Stem Cells on PEDOT:PSS Conductive Polymer Scaffolds.

The investigation of the effects of electrical and mechanical stimulations on chondrogenesis in tissue engineering scaffolds is essential for realizing successful cartilage repair and regeneration. The aim of articular cartilage tissue engineering is to enhance the function of damaged or diseased articular cartilage, which has limited regenerative capacity. Studies have shown that electrical stimulation (ES) promotes mesenchymal stem cell (MSC) chondrogenesis, while mechanical stimulation (MS) enhances the chondrogenic differentiation capacity of MSCs. Therefore, understanding the impact of these stimuli on chondrogenesis is crucial for researchers to develop more effective tissue engineering strategies for cartilage repair and regeneration. This study focuses on the preparation of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) conductive polymer (CP) scaffolds using the freeze-drying method. The scaffolds were fabricated with varying concentrations (0, 1, 3, and 10 wt %) of (3-glycidyloxypropyl) trimethoxysilane (GOPS) as a crosslinker and an additive to tailor the scaffold properties. To gain a comprehensive understanding of the material characteristics and the phase aggregation phenomenon of PEDOT:PSS scaffolds, the researchers performed theoretical calculations of solubility parameters and surface energies of PSS, PSS-GOPS, and PEDOT polymers, as well as conducted material analyses. Additionally, the study investigated the potential of promoting chondrogenic differentiation of human adipose stem cells by applying external ES or MS on a PEDOT:PSS CP scaffold. Compared to the group without stimulation, the group that underwent stimulation exhibited significantly up-regulated expression levels of chondrogenic characteristic genes, such as SOX9 and COL2A1. Moreover, the immunofluorescence staining images exhibited a more vigorous fluorescence intensity of SOX9 and COL II proteins that was consistent with the trend of the gene expression results. In the MS experiment, the strain excitation exerted on the scaffold was simulated and transformed into stress. The simulated stress response showed that the peak gradually decreased with time and approached a constant value, with the negative value of stress representing the generation of tensile stress. This stress response quantification could aid researchers in determining specific MS conditions for various materials in tissue engineering, and the applied stress conditions could be further optimized. Overall, these findings are significant contributions to future research on cartilage repair and biophysical ES/MS in tissue engineering.