Siloxane Hybrid Research Articles

Hybrid siloxane oligomer: A promising consolidant for the conservation of powdered tremolite jade artifacts

Jade has played a pivotal role in the political, economic, cultural, and technological development of ancient societies. However, numerous tremolite jade artifacts unearthed from archaeological sites exhibit various deterioration patterns due to natural weathering and human activities. Among these, powdering is the most detrimental form of degradation, significantly affecting the physical characteristics of artifacts, as well as archaeological research and museum exhibitions. This paper develops a novel hybrid siloxane oligomer as a potential consolidant for powdered tremolite jade artifacts and compares it with traditional consolidants, including acrylic resin and ethyl silicate. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and X-ray fluorescence (XRF) analyses show that the jade samples used in the experiment are predominantly composed of tremolite. Various techniques are employed to evaluate and compare the effectiveness of the three consolidants, including color variation tests, open porosity tests, contact angle measurements, peeling tests, hardness tests, ultra-depth-of-field microscopy, and scanning electron microscopy (SEM). The novel hybrid siloxane oligomer demonstrates superior consolidation effects, with consolidated samples showing significant improvements in mechanical properties, reaching a Leeb hardness of 163 HL, while maintaining color variations within acceptable limits (ΔE = 3.87). The results demonstrate the potential of the novel hybrid siloxane oligomer in consolidating powdered tremolite jade artifacts.

Highly stable wavelength converting composite based on sol–gel derived siloxane-encapsulated luminescent nanocrystals

Luminescent nanocrystals (NCs) have emerged as the high-performance wavelength converting materials in next-generation displays and energy conversion devices due to their unique optophysical properties, such as large Stokes or anti-Stokes shifts, narrow emission bandwidth, and tunable bandgap depending on size or composition. However, poor long-term stability in high temperature and humidity remains a critical issue for device applications. This instability is primarily due to irreversible changes in surface ligands or chemical structures/compositions when exposed to various severe environments. Various strategies have been reported to address these issues, such as the formation of inorganic shell layers and the fabrication of polymer-based nanocomposites. Although these strategies have improved stability, they exhibit degraded properties during long-term aging. Recently, sol–gel derived siloxane hybrid materials have been introduced to achieve stability for various NCs under actual operating conditions of displays and optoelectronic devices. This review will address recent progress in developing siloxane-encapsulated NCs with high stability in high temperature/humidity and under continuous light exposure. It will also introduce results on enhancing the environmental stability of various NCs, including lanthanide-doped transition metal-based NCs, semiconducting NCs, and metal halide perovskite NCs, as well as demonstrations of reliable devices.Graphical

Flexible-rigid hybrid siloxane network for stone heritage conservation

Siloxane oligomers produced through the hydrolysis of tri-alkoxysilanes or tetra-alkoxysilanes have been widely used as consolidants for stone heritage. However, the resulting xerogels tend to crack due to the volume shrinkage after curing. In this study, a novel flexible-rigid hybrid siloxane oligomer material is designed by the self-catalyzed copolymerization of di-alkoxysilane (3-Aminopropyl) dimethoxymethylsilane with tetra-alkoxysilane tetraethyl orthosilicate. The flexible linear SiOSi segments produced by di-alkoxysilane are inserted into the tetra-alkoxysilane derived rigid three-dimensional silicon-oxygen domains, as confirmed by spectroscopic characterizations. This unique structure alleviates the shrinkage stress during curing and enables the formation of crack-free xerogels. Therefore, the hybrid siloxane oligomer can invade into the interior of weathered stone to form one three-dimensional continuous network to strengthen its fragile structure. As a result, the flexible-rigid hybrid siloxane oligomer outperforms both as-made polysiloxane consolidant and commercial consolidant for the consolidation of the weathered Tianlong Mountain Grottoes stone samples. The consolidation treatment was evaluated in terms of effectiveness (Leeb hardness, ultrasonic velocity and compressive strength) and compatibility (pore size distribution, water vapor transmission rate and color variation). Following the treatment, the consolidated samples demonstrate remarkable improvements in mechanical properties, reaching a Leeb hardness of 410 HL and a compressive strength of 8.98 Mpa. Additionally, permeability and color variation of the stone after consolidation are all within acceptable ranges. The results confirm the positive consolidation performance of the flexible-rigid hybrid siloxane oligomer on weathered Tianlong Mountain Grottoes stone, indicating promising practical applications.

Hybrid Siloxane Materials Based on a Mutually Reactive Epoxy–Amine System: Synthesis, Structure, and Thermal Stability Investigations

Hybrid siloxane materials based on a mutually reactive epoxy–amine system are organic-inorganic hybrid materials synthesized via the sol–gel reaction of siloxane precursors, followed by the polymerization of organo-functionalized oligosiloxanes. Therefore, using a new hybrid system as the reaction product resulting from the reaction between 1,3-bis(3-glycidoxypropyl)-l, 1,3,3-tetramethyldisiloxane—C16H34O5Si2—(gp-DS) and p-phenylenediamine—C6H4(NH2)2—(PPD), an aromatic diamine, was obtained. The chemical structure of the synthesized hybrid siloxane material was confirmed via Fourier Transform Infra-Red (FTIR) spectroscopy, mass spectrometry (MS), and 1H-NMR spectroscopy. The morphology and surface chemical composition was highlighted via scanning electron microscopy (SEM) equipped with an EDX elemental analysis system. Further, the thermal stabilities of the prepared hybrid siloxane and its precursors have been investigated via thermogravimetric analysis (TGA), proving the modification of epoxy-functional disiloxanes with a paraphenylenediamine reagent that made it possible to produce hybrid siloxane materials with very good thermal stabilities and dual weak hydrophilic/hydrophobic surfaces.

Novel PVA-Hyaluronan-Siloxane Hybrid Nanofiber Mats for Bone Tissue Engineering.

Hyaluronan (HA) is a natural biodegradable biopolymer; its biological functions include cell adhesion, cell proliferation, and differentiation as well as decreasing inflammation, angiogenesis, and regeneration of damaged tissue. This makes it a suitable candidate for fabricating nanomaterials with potential use in tissue engineering. However, HA nanofiber production is restricted due to the high viscosity, low evaporation rate, and high surface tension of HA solutions. Here, hybrids in the form of continuous and randomly aligned polyvinyl alcohol (PVA)-(HA)-siloxane nanofibers were obtained using an electrospinning process. PVA-HA fibers were crosslinked by a 3D siloxane organic-inorganic matrix via sol-gel that restricts natural hydrophilicity and stiffens the structure. The hybrid nanofiber mats were characterized by FT-IR, micro-Raman spectroscopy, SEM, and biological properties. The PVA/HA ratio influenced the morphology of the hybrid nanofibers. Nanofibers with high PVA content (10PVA-8 and 10PVA-10) form mats with few beaded nanofibers, while those with high HA content (5PVA-8 and 5PVA-10) exhibit mats with mound patterns formed by "ribbon-like" nanofibers. The hybrid nanofibers were used as mats to support osteoblast growth, and they showed outstanding biological properties supporting cell adhesion, cell proliferation, and cell differentiation. Importantly, the 5PVA-8 mats show 3D spherical osteoblast morphology; this suggests the formation of tissue growth. These novel HA-based nanomaterials represent a relevant advance in designing nanofibers with unique properties for potential tissue regeneration.

NIR‐emitting Electrochromic Windows for Cold Climate Region Buildings

AbstractElectrochromic devices (ECDs) comprising visible/near‐infrared (NIR) transparent amorphous indium zinc oxide (a‐IZO) outermost layers and novel NIR‐emitting electrolytes are proposed for smart windows of buildings in cold climate regions. The electrolytes are composed of a di‐urethane cross‐linked poly(oxyethylene)(POE)/siloxane hybrid matrix (d‐Ut(600), 600 is the average molecular weight of the POE chains in gmol−1), 1‐butyl‐3‐methylimidazolium chloride ionic liquid, and the Er(tta)3(H2O)2 complex (tta− is 2‐thenoyltrifluoracetonate). The electrolytes, synthesized by sol‐gel route, were obtained as transparent, flexible, and hydrophilic monoliths with nanoscale surface roughness, exhibiting emission in the NIR wavelength region. The first electro‐optical tests, performed in 2019, with an archetypal ECD including amorphous tungsten oxide and crystalline nickel oxide as EC layers, a‐IZO as outermost layers, and d‐Ut(600)400Er(tta)3(H2O)2[Bmim]Cl (400 is the molar ratio of oxyethylene units/Er3+ ion) as the electrolyte, demonstrated rather low coloration efficiency (CEin/CEout) values of −4/+6 cm2 C−1 at 555 nm. After 3 years of storage at rest in the dark and at room temperature, the same device demonstrates a huge performance enhancement, leading to CEin/CEout values about two orders of magnitude higher, apart from higher optical density, and improved cycling stability. In addition, this device offers a bright hot, and semi‐bright warm dual modulation operation suitable for smart windows of skylights, roof lights, upper windows, inclined glazing, and privacy glazing of buildings located in cold climate regions.

Environmentally stable luminescent perovskite nanocrystals passivated and encapsulated by siloxane hybrids enabling reliable color-converted organic light-emitting diodes

Environmentally stable luminescent perovskite nanocrystals passivated and encapsulated by siloxane hybrids enabling reliable color-converted organic light-emitting diodes

BINOL and triazole-containing Janus rings and 29-8-29-membered tricyclic ladder-type hybridized siloxane: application in the fluorescence sensing of anions.

Tetrachloro- and tetraazide-substituted all-cis-tetraphenylcyclotetrasiloxanes (all-cis-T4) 2 and 3 were synthesized in high yields and were fully characterized. Then the precursor 3 underwent CuAAC click reaction with monopropargyl BINOL 4 and dipropargyl BINOL 6 to give the novel BINOL and triazole-containing all-cis-T4 cyclic siloxane 5 and the 29-8-29-membered-ring ladder-type hybrid siloxane 7. The sensing ability of compounds 5 and 7 towards anions was studied as well, and it was observed that 7 could selectively recognize iodides through synergistic C-H⋯I hydrogen bonding, resulting in an impressive fluorescence quenching with a Ksv of 8.10 × 104 M-1.

Preparation and Drug Release Profile of Chitosan-Siloxane Hybrid Capsules Coated with Hydroxyapatite.

Chitosan is a cationic polymer that forms polymerized membranes upon reaction with anionic polymers. Chitosan−carboxymethyl cellulose (CMC) capsules are drug delivery carrier candidates whose mechanical strength and permeability must be controlled to achieve sustained release. In this study, the capsules were prepared from chitosan−γ-glycidoxypropyltrimethoxysilane (GPTMS)−CMC. The mechanical stability of the capsules was improved by crosslinking the chitosan with GPTMS. The capsules were then coated with hydroxyapatite (HAp) by alternately soaking them in calcium chloride solution and disodium hydrogen phosphate solution to prevent rapid initial drug release. Cytochrome C (CC), as a model drug, was introduced into the capsules via two routes, impregnation and injection, and then the CC released from the capsules was examined. HAp was found to be deposited on the internal and external surfaces of the capsules. The amount of CC introduced, and the release rate were reduced by the HAp coating. The injection method was found to result in the greatest CC loading.

Effects of the silicon-containing chemical species dissolved from chitosan–siloxane hybrids on nerve cells

Effects of the silicon-containing chemical species dissolved from chitosan–siloxane hybrids on nerve cells

Epoxy-based siloxane composites for electronic packaging: Effect of composition and molecular structure of siloxane matrix on their properties

Epoxy-based composites are widely used in electronic packaging because of their excellent moldability and insulation properties. However, commercial epoxy-based materials have low thermal stability and high thermal expansion. Herein, we report epoxy siloxane/silica composites that improve the thermal, mechanical, and insulating properties of epoxy resin by introducing a sol–gel-synthesized siloxane hybrid and silica particles. We develop two types of epoxy-based composites with different siloxane molecular structures (branch and linear) and investigate the changes in their properties with different compositions and siloxane structures. Branched siloxane structure leads to hard and low insulating properties, whereas linear siloxane structure results in soft and high insulating properties. Both epoxy siloxane/silica composites exhibit high thermal stability and low thermal expansion. These properties are greatly improved by the incorporation of silica particles. Finally, we confirm the feasibility of the use of developed composites in electronic packaging, wherein two types of epoxy-based siloxane/silica composites are coated onto a commercial metallic substrate without any deformation. Our epoxy-based composites have significant potential as high-performance and robust electronic packaging materials. In addition, our composite-design approach can easily control the composite characteristics of mechanics and insulation, and improve both these properties by employing silica particles with a homogeneous distribution.

Size Exclusion and Ion Exchange Chromatographic Hardware Modified with a Hydrophilic Hybrid Surface.

Certain biomolecules have proven to be difficult to analyze by liquid chromatography (LC), especially under certain chromatographic conditions. The separation of proteins in aqueous mobile phases is one such example because there is the potential for both hydrophobic and ionic secondary interactions to occur with chromatographic hardware to the detriment of peak recovery, peak shape, and the overall sensitivity of the LC analysis. To decrease non-specific adsorption and undesired secondary interactions between column hardware and biomolecules, we have developed and applied a new hydrophilically modified hybrid surface (h-HST) for size exclusion chromatography (SEC) and anion exchange (AEX) separations of proteins and nucleic acids. This surface incorporates additional oxygen and carbon atoms onto an ethylene bridge hybrid siloxane polymer. As a result, it exhibits reduced electrostatic properties and hydrophilicity that facilitates challenging aqueous separations. Flow injection tests with a phosphate buffer showed superior protein recovery from an h-HST frit when compared to unmodified ethylene-bridged hybrid HST, titanium, stainless steel, and PEEK frits. When applied to SEC of rituximab, ramucirumab, and trastuzumab emtansine with a 50 mM ammonium acetate buffer, this new hydrophilic chromatographic hardware yielded improved monomer and aggregate recovery, higher plate numbers, and more symmetrical peaks. AEX columns also benefited from h-HST hardware. An acidic mAb (eculizumab) showed improved recovery, more stable retention, and a sharper peak when eluted from an h-HST versus SS column. Moreover, AEX separations of intact mRNA samples (Cas9 and EPO mRNA) were improved, where it was seen that h-HST column hardware provided higher sensitivity and more repeatable peak areas from injection to injection. As such, there is significant potential in the use of h-HST chromatographic hardware to facilitate more robust and more sensitive analyses for a multitude of challenging separations and analytes.

Gelatin–Siloxane Hybrid Monoliths as Novel Heavy Metal Adsorbents

Novel gelatin-siloxane hybrid monoliths for heavy metal removal were prepared in the chemical reaction of gelatin with organomodified silicone containing epoxy group. Obtained porous hybrid materials were applied for adsorption of Cu(II), Cd(II) and Pb(II) from aqueous solutions. In this paper, the influence of siloxane amount used for the modification of gelatin on adsorbent stability and heavy metal removal was examined. The effect of pH values of the immersion liquid, as well as the contact time, was studied. Morphology, compressive strength and water absorption of hybrid monoliths were investigated. Desorption tests were also performed. The results showed that the higher the amount of the siloxane, the better stability of the hybrid monoliths in aqueous solutions. The highest values of adsorption capacity were observed for Pb(II) ions. The experimental maximum adsorption capacity determined for hybrid monoliths was 3.75 mg/g for Pb(II), 1.76 mg/g for Cu(II) and 1.5 mg/g for Cd(II). The desorption of metal ions for hybrid monoliths stable in aqueous solutions reached 70%.

Comparison of Dimensional Accuracy of Three Different Impression Materials Using Three Different Techniques for Implant Impressions: An In Vitro Study

To compare the dimensional accuracy of polyether, polyvinyl siloxane, and polyether polyvinyl siloxane hybrid impression materials using closed tray, open tray splinted, and open tray nonsplinted coping impression techniques and to find out the best suitable impression material and technique combination for implant impressions. The sample size of the study was 45. The combinations of materials and techniques were divided into nine groups, namely polyvinyl siloxane with closed tray, polyvinyl siloxane with open tray nonsplinted copings, polyvinyl siloxane with open tray splinted copings, polyether with closed tray, polyether with open tray nonsplinted copings, polyether with open tray splinted copings, polyvinyl siloxane-polyether hybrid with closed tray, polyvinyl siloxane-polyether hybrid with open tray nonsplinted copings, and polyvinyl siloxanepolyether hybrid with open tray splinted copings. Five samples of each group were evaluated. A total of 45 impressions were taken. A stainless steel master metal framework with three internal hex implants was fabricated and used to generate the samples. A common condensation silicone putty spacer was applied over the impression copings attached to the implants, which was then duplicated. All trays were fabricated on this duplicated silicone die using light cure acrylic resin. Trays to be used for open tray techniques had their top removed for gaining access to screws of the impression copings. Splinting of coping for OS group was done using pattern resin. Impressions were poured, and master cast was generated. Interimplant distance was measured using stereomicroscope and an image analyzing software. Open nonsplinted technique resulted in significantly better replication of implant positions compared to open splinted and closed techniques. Hybrid impression material depicted significantly better dimensional accuracy than polyether and polyvinyl siloxane. Hybrid open nonsplinted depicted least mean difference in interimplant distance, followed by hybrid open splinted and polyether open splinted groups. Polyvinyl siloxane closed tray showed maximum difference in interimplant distance in comparison with other groups. Polyvinyl siloxane-polyether hybrid impression material and open nonsplinted technique gave best replication of implant positions on the master cast. Accuracy of impressions and casts is of great importance for the fabrication and long-term clinical success of precisely fitting implant-retained prostheses.

Asymmetric Hybrid Siloxane Side Chains for Enhanced Mobility and Mechanical Properties of Diketopyrrolopyrrole-Based Polymers.

High performance organic field effect transistor devices based on intrinsically scalable materials are of great significance in wearable electronics. In this work, an exclusive approach is reported to rationale the carrier mobility and stretchability of the conjugate polymers (CPs) by modifying the symmetry of the side chains species. Semiconductor CPs with symmetrical alkyl side chains (P(C-C)), symmetrical siloxane side chains (P(Si-Si)), and asymmetrical silicon-carbon side chains (P(C-Si)) are synthesized to investigate the influence of these side chains on the carrier mobility and mechanical behavior. The result shows that silicon-carbon asymmetric side chains can modulate the aggregation degree of polymer chains with a coherence length of 134 Å and maintain the mobility at 0.90 cm2 V-1 s-1 . P(C-Si) exhibits superior tensile properties that even elongation up to 100% the value of mobility retains a majority properties. The main reason is that the lowest coherence length of P(C-Si) polymer leads to an increased proportion of amorphous zones in its polymer film, which efficiently dissipates mechanical stresses. This study provides an efficient strategy for the design and synthesis of the CPs with high carrier transport properties-mechanical stability.

Highly transparent and resilient urethane-methacrylate siloxane composite for hard, yet stretchable protective coating

Although foldable electronic devices have been commercially available for some time now, flexible protective coating with sufficient reliability is yet to be achieved. The integration of polyurethane acrylate and an organic-inorganic (O-I) siloxane hybrid is proposed in this study as a promising protective coating, where both high strength and stretchability could be achieved to allow for the needed reliability for foldable electronics. In this work, a urethane-methacrylate siloxane hybrid (U-MSH) composite was fabricated by a physical blending of methacrylate-functionalized oligosiloxane and acrylate terminated urethane prepolymer followed by curing. The U-MSH composite demonstrates excellent performance in terms of optical (e.g., transmittance, Abbe number, UV stability) and mechanical properties (e.g., resilience under compression, tension, and scratch). These outstanding properties can be attributed to the synergetic effect of the combined polyurethane acrylate and O-I siloxane hybrid. Excellent reliability of U-MSH coating film is successfully demonstrated using an outward-bending test, suggesting that U-MSH has great potential as a protective material for flexible electronics.

Elongation improvement of transparent and flexible surface protective coating using polydimethylsiloxane-anchored epoxy-functionalized siloxane hybrid composite for reliable out-foldable displays

Flexible surface protective coating in out-foldable devices should possess high elongation with high surface hardness. However, the two characteristics in conventional protecting materials are mutually exclusive. Here, we report a simple and effective composite design strategy to realize high elastic, yet still hard out-foldable and transparent surface protective coating material using molecular hybridization between polydimethylsiloxane (PDMS) and epoxy-functionalized siloxane matrix (ESH) via an in situ sol-gel reaction, forming siloxane linkages. Chemically crosslinked PDMS with ESH (P-ESH) makes optical transparency and greatly improves the elongation property while retaining the surface hardness of ESH due to the flexible and long-siloxane backbone of PDMS. As a result, we obtain the high-performance surface protective coating with greatly improved elongation (2.05% of fracture strain, 60% increase of bare ESH) and high surface hardness (pencil hardness: 4H @ 20 μm thickness). We thoroughly characterize the mechanical behavior of P-ESH combined with microscopic (nano-scratch and nanoindentation tests) and macroscopic views (tensile test with digital image correlation methods). Enhanced elongation property with high surface hardness is induced by fully-recovery characteristics of P-ESH from external force. In addition, the fabricated P-ESH shows excellent reliability under repeated out-folding (5 mm of folding radius), continuous abrasion (steel wool test: 5,000 cycles), acid or base solutions, and ultraviolet irradiation. Our extensible transparent surface protective coating composite provides a great potential for application to next-generation out-foldable devices.

A calorimetric, volumetric and combined SANS and SAXS study of hybrid siloxane phosphocholine bilayers

Siloxanes are molecules used extensively in commercial, industrial, and biomedical applications. The inclusion of short siloxane chains into phospholipids results in interesting physical properties, including the ability to form low polydispersity unilamellar vesicles. As such, hybrid siloxane phosphocholines (SiPCs) have been examined as a potential platform for the delivery of therapeutic agents. Using small angle X-ray and neutron scattering, vibrating tube densitometry, and differential scanning calorimetry, we studied four hybrid SiPCs bilayers. Lipid volume measurements for the different SiPCs compared well with those previously determined for polyunsaturated PCs. Furthermore, the different SiPC’s membrane thicknesses increased monotonically with temperature and, for the most part, consistent with the behavior observed in unsaturated lipids such as, 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine and 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine, and the branched lipid 1,2-diphytanoyl-sn-glyerco-3-phosphocholine (DPhyPC).

Evaluation of anti-corrosive properties of epoxidized rubber and siloxane hybrid coatings

ABSTRACT Elastomeric hybrid films were produced from the epoxidized nitrile rubber with the 3-glycidyloxypropyl-trimethoxysilane (GPTMS) inorganic precursor by the sol–gel process. There were no significant changes in the thermal properties of hybrids in relation to pure epoxidized rubber. The degree of swelling decreased while the mechanical resistance increased with increasing GPTMS content. The sol–gel process was performed on metal plates, which were then subjected to a corrosion process by immersion in NaCl solution and evaluated by Electrochemical Impedance Spectroscopy. The resistance and the capacitance values of the nitrile rubber coating are 8.8 × 103 Ω cm2 and 1.9 × 10−4 F cm−2, whereas for the hybrid with 38 phr of GPTMS the values are 2.3 × 106 Ω cm2 and 15.8 × 10−10 F cm−2, respectively, indicating higher cross-link density, less electrolyte absorption, less degradation, greater adherence to the metal surface via silane groups and, consequently, better corrosion protection achieved by the hybrid films.

Sol–gel synthesized siloxane hybrid materials for display and optoelectronic applications

Recently, displays and optoelectronics have made remarkable development because they are the most frequently exposed applications to humanity. The pixel size has become smaller and a new form factor is needed for displays and optoelectronics beyond rigid ones. New material breakthroughs enabling new form factors with plastic-like flexibility, mechanical toughness as well as glass-like thermal/mechanical resistance and low thermal expansion are required. Sol–gel-derived siloxane hybrid material (Hybrimer), showing synergetic properties of organic and inorganic (O–I) materials, can be realized by chemical hybridization and dense O–I co-networks. In addition, the characteristics of hybrimer can be easily optimized via control of organic functional groups, sol–gel reaction, and polymerization steps. First, a sol–gel reaction and polymerization, which enables chemical hybridization of O–I groups, are introduced. Then, the various display and optoelectronic applications using hybrimer achieved by control of properties are provided: (i) patterning, (ii) passivation, (iii) glass-fabric reinforced film, and (iv) color conversion films. This paper includes a brief overview of fabrication process and applications using hybrimer developed over the past decades.