Search Results (13)

In this study, we report the synthesis and characterization of aminated poly(methyl silsesquioxane)-based hydrogels ((AP/MS)SO-hydrogels) as potential enzyme-sensitive vehicles for antianemic drugs. The hydrogels were synthesized via sol–gel polymerization and functionalized with amine groups. Characterization techniques included Congo red assay, Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy, elemental analysis, ¹³C NMR, ²⁹Si NMR, and ATR-FTIR spectroscopy and microscopy of hydrogels. The sorption of ferric chloride and ferrous D-gluconate, as well as complexes of ferrous D-gluconate with HPCD, was evaluated. Crosslinking of the gel with bifunctional agents was performed to create a new amide enzyme-sensitive bond, followed by infrared characterization of the crosslinked product. Trypsin-mediated degradation studies demonstrated the sensitivity of the hydrogel to enzymatic cleavage under model conditions. Iron release experiments in gastric and intestine-simulating media confirmed prolonged release. Overall, our findings suggest that aminated PMSSO-hydrogels hold promise as versatile and biocompatible carriers for targeted delivery of antianemic agents, warranting further exploration in preclinical and clinical applications. Full article

Silica fillers have been a cornerstone in chemical technology due to their versatility, availability, and ease of integration into various formulations. Recent advancements, including chlorine-free synthesis of alkoxysilanes, have paved the way for alternative materials like polymethylsilsesquioxane (PMSSO). This study explores the structural evolution and properties of a hydrophobic PMSSO xerogel, synthesized through hydrolytic polycondensation of methyltriethoxysilane (MTEOS). PMSSO exhibits exceptional hydrophobicity, high specific surface area, and compatibility with polymer matrices, making it a promising filler for applications in rubber products, lubricants, and cosmetics. We developed a straightforward synthesis method for producing PMSSO xerogel that avoids toxic solvents and organochlorosilanes, ensuring safety and sustainability. The reaction conditions, particularly the amount of alkali and neutralization parameters, were found to significantly influence the properties of the final xerogels, such as specific surface area. Optimization of the synthesis parameters allow for obtaining PMSSO xerogels with a specific surface area about 600 m²/g. These findings underscore PMSSO’s potential as a versatile, eco-friendly alternative to conventional silica fillers, offering tailored properties for diverse industrial applications. Full article

Anemia is a global health problem that affects both adults and children, but treatment is hampered by serious side effects, primarily associated with the gastrointestinal tract with oral administration of drugs. In this study, we aimed to develop an oral form of iron compounds using polymethylsilsesquioxane hydrogels. To boost loading efficiency and prolong release, the iron compounds (FeCl₃ and ferrous D-Gluconate) are incorporated into a guest–host complex with 2-hydroxypropyl-beta-cyclodextrin. We used PRXD, SEM, EDX mapping, and FTIR to investigate the complex formation, as well as the incorporation of such complexes into hydrogels. The optimal system underlines a combination of ferrous D-Gluconate and HPCD in a 1:1 molar ratio, embedded into a hydrogel with a modest quantity of silicate crosslinks. We demonstrated the slowing of iron release in a gastric media. Mathematical investigation revealed that the Higuchi mechanism releases iron from the hydrogel. Full article

Aerogels are a class of materials that have gained increasing attention over the past several decades due to their exceptional physical and chemical properties. These materials are highly porous, with a low density and high surface area, allowing for applications such as insulation, catalysis, and energy storage. However, traditional aerogels, such as pure silica aerogels, suffer from brittleness and fragility, which limit their usefulness in many applications. Herein, we have addressed this problem by using organosilicon compounds, namely polymethylsilsesquioxane derivatives, for the synthesis of aerogel-like materials. Specifically, we have developed a novel approach involving surfactant-free synthesis of microcapsules from partially PEGylated hyperbranched polymethylethoxysiloxane. Due to the highly diphilic nature of these compounds, they readily concentrate at the oil/water interface in aqueous emulsions encapsulating oil droplets. During the subsequent condensation, the organosilicon precursor is consumed for hexane encapsulation (yielding hollow microcapsules) followed by the formation of a continuous condensed phase. Concurrently, methyl groups ensure the hydrophobicity of the resulting materials, which eliminates the need of using additional reagents for their hydrophobization. Full article

To enable rapid osteointegration in bioceramic implants and to give them osteoinductive properties, scaffolds with defined micro- and macroporosity are required. Pores or pore networks promote the integration of cells into the implant, facilitating the supply of nutrients and the removal of metabolic products. In this paper, scaffolds are created from ß-tricalciumphosphate (ß-TCP) and in a novel way, where both the micro- and macroporosity are adjusted simultaneously by the addition of pore-forming polymer particles. The particles used are 10–40 wt%, spherical polymer particles of polymethylmethacrylate (PMMA) (Ø = 5 µm) and alternatively polymethylsilsesquioxane (PMSQ) (Ø = 2 µm), added in the course of ß-TCP slurry preparation. The arrangement of hydrophobic polymer particles at the interface of air bubbles was incorporated during slurry preparation and foaming of the slurry. The foam structures remain after sintering and lead to the formation of macro-porosity in the scaffolds. Furthermore, decomposition of the polymer particles during thermal debindering results in the formation of an additional network of interconnecting micropores in the stabilizing structures. It is possible to adjust the porosity easily and quickly in a range of 1.2–140 μm with a relatively low organic fraction. The structures thus prepared showed no cytotoxicity nor negative effects on the biocompatibility. Full article

Polymethylsilsesquioxane (PMSQ) has become a kind of widely studied filler used in the electronic circuit board substrates due to its organic–inorganic hybrid structure, low dielectric constant, and good thermal stability, among other factors. Herein, the PMSQ microspheres were prepared by a two-step acid–base-catalyzed sol–gel method; the influences of reaction conditions including the ratio of water/methyltrimethoxysilane (MTMS), reaction temperature, concentration of the catalyst, and stirring time were systematically investigated; and the optimized reaction condition was then obtained towards a narrow particle size distribution and good sphericity. The microstructure of PMSQ microspheres was analyzed by the infrared spectrum and X-ray diffraction (XRD), which indicated that the as-prepared PMSQ had a ladder-dominant structure. The thermogravimetric analysis (TGA) demonstrated an excellent thermal stability of as-prepared PMSQ microspheres. More specifically, the dielectric constants at high frequency (1~20 GHz) of as-prepared PMSQ microspheres were measured to be about 3.7, which turned out a lower dielectric constant compared to SiO₂ powder (≈4.0). This study paves the way to further improve the performance of the electronic circuit board substrates for the application of high-frequency electronic packaging. Full article

Unmanned aerial vehicles (UAVs) or drones are attracting increasing interest in the aviation industry, both for military and civilian applications. The materials used so far in the manufacture of UAVs are wood, plastic, aluminum and carbon fiber. In this regard, a new family of high-density polyethylene (HDPE) nanocomposites reinforced with polymethylsilsesquioxane nanoparticles (PMSQ), with mechanical performances significantly superior to those of pure HPDE, has been prepared by a fusion-combination process. Their viscoelastic properties were determined by oscillatory shear tests and their viscoelastic behavior characterized by the Lodge integral model. Then, the Lagrangian formulation and the membrane theory assumption were used in the explicit implementation of the dynamic finite element formulation. For the forming phase, we considered the thermodynamic approach to express the external work in terms of closed volume. In terms of von Mises stress distribution and thickness in the blade, the results indicate that HDPE-PMSQ behaves like virgin HDPE. Furthermore, its materials, for all intents and purposes, require the same amount of energy to form as HDPE. Full article

Numerical modeling of the thermoforming process of polymeric sheets requires precise knowledge of the viscoelastic behavior under conjugate effect pressure and temperature. Using two different experiments, bubble inflation and dynamic mechanical testing on a high-density polyethylene (HDPE) nanocomposite reinforced with polymethylsilsesquioxane HDPE (PMSQ–HDPE) nanoparticles, material constants for Christensen’s model were determined by the least squares optimization. The viscoelastic identification relative to the inflation test seemed to be the most appropriate for the numerical study of thermoforming of a thin PMSQ–HDPE part. For this purpose, the finite element method was considered. Full article

The effect of glycerol (GLY) and poly(ethylene glycol) (PEG) additives on the properties of silica aerogel-like monoliths obtained from methyltrimethoxysilane (MTMS) precursor was assessed. The tested molar ratios of additive/precursor were from 0 to 0.1 and the lowest bulk densities were obtained with a ratio of 0.025. When a washing step was performed in the sample containing the optimum PEG ratio, the bulk density could be reduced even further. The analysis of the material’s microstructure allowed us to conclude that GLY, if added in an optimum amount, originates a narrower pore size distribution with a higher volume of mesopores and specific surface area. The PEG additive played a binder effect, leading to the filling of micropores and the appearance of large pores (macropores), which caused a reduction in the specific surface area. The reduction of the bulk density and the microstructural changes in the aerogels induced by adding a small amount of these additives confirm the possibility of fine control of properties of these lightweight materials. The achieved high porosity (97%) and low thermal conductivity (~35 mW·m⁻¹·K⁻¹) makes them suitable to be used as thermal insulators. Full article

Polymethylsilsesquioxane (PMSQ) nanoparticles with mass percentages of 0, 2.5, 5.0, 7.2, 9.4 wt %, respectively, were constructed by molecular dynamics methods in this paper. Composite molecular models were established using PMSQ and MPIA (poly-metaphenylene isophthalamide) fiber. The influence of different PMSQ contents on the thermal stability of meta-aramid insulation paper was analyzed from the parameters of mechanical property, interaction energy, and mean square displacement. The results showed that the trend of mechanical properties decreased with the increase of PMSQ content. When the PMSQ content was 2.5 wt %, the mechanical properties of the composited model were the best, which was about 24% higher than that of the unmodified model. From an intermolecular bonding and nonbonding point of view, the energy parameters of composite model with the 2.5 wt % content was better than those of the composite model with other contents. Therefore, it is considered that MPIA can interact better with the 2.5 wt % content PMSQ composite model. When the PMSQ content is 2.5 wt %, the overall chain movement in the composite model is slower than that of the unmodified model, which can effectively inhibit the diffusion movement of the MPIA chain. In general, the thermal stability of composite molecular models MPIA and PMSQ (2.5 wt %) was better improved. Full article

Information on localized states at the interfaces of solution-processed organic semiconductors and polymer gate insulators is critical to the development of printable organic field-effect transistors (OFETs) with good electrical performance. This paper reports on the use of impedance spectroscopy to determine the energy distribution of the density of interface states in organic metal-insulator-semiconductor (MIS) capacitors based on poly(3-hexylthiophene) (P3HT) with three different polymer gate insulators, including polyimide, poly(4-vinylphenol), and poly(methylsilsesquioxane). The findings of the study indicate that the impedance characteristics of the P3HT MIS capacitors are strongly affected by patterning and thermal annealing of the organic semiconductor films. To extract the interface-state distributions from the conductance of the P3HT MIS capacitors, an equivalent circuit model with continuum trap states is used, which also takes the band-bending fluctuations into consideration. In addition, the relationship between the determined interface states and the electrical characteristics of P3HT-based OFETs is investigated. Full article

Immobilizing particles on beads, fibers, or filaments, when only one side is exposed to the reaction medium and therefore can be selectively functionalized, is a scalable and easy to control strategy for the fabrication of amphiphilic Janus particles. Here we describe a new, robust method for the fabrication of amphiphilic Janus particles based on immobilization of polymethylsilsesquioxane (PMSQ) particles on polycarbonate (PC), a high impact-resistance polymer with superior mechanical properties. The immobilization of the particles on the PC microspores is performed via inverse solvent displacement method. PMSQ particles are added to a PC solution in tetrahydrofuran (THF), a good solvent for PC. The solution is then precipitated by the introduction of aqueous surfactant solution (antisolvent for PC) under an ultrasonic field. It is important to note that THF and water are miscible and do not form emulsion. During precipitation, PMSQ particles are assembled onto the surface of the PC spherical precipitates/microspheres. The exposed hemispheres of the PMSQ particles are then selectively silanized by (3-Aminopropyl)triethoxysilane (APTES) to introduce amine groups on their surface. To increase the polarity of the functionalized hemispheres, the amine groups are further modified to introduce carboxyl groups. SEM characterization confirms the fine embedment of PMSQ particles onto the PC microspheres. Covalent attachment of silica nanoparticles (NPs) to the functionalized hemispheres of the resulting particles along with fluorescent confocal microscopy conclusively prove the successful fabrication of amphiphilic Janus particles. The immobilization of particles onto highly rigid polymeric microspheres such as PC may pave the way for the development of a robust fabrication procedure with high resistance to temperature fluctuations and harsh mixing conditions that can arise during preparation. This method can be implemented toward a large variety of other synthetic commercial polymers such as polyamide, polyether sulfones, Polyether, ether ketone, or similar. Full article

Polymethylsilsesquioxane (PMSQ) aerogels obtained from methyltrimethoxysilane (MTMS) are well-known high-performance porous materials. Highly transparent and hydrophobic PMSQ aerogel would play an important role in transparent vacuum insulation panels. Herein, the co-precursor approach and supercritical modification method were developed to prepare the PMSQ aerogels with high transparency and superhydrophobicity. Firstly, benefiting from the introduction of tetramethoxysilane (TMOS) in the precursor, the pore structure became more uniform and the particle size was decreased. As the TMOS content increased, the light transmittance increased gradually from 54.0% to 81.2%, whereas the contact angle of water droplet decreased from 141° to 99.9°, ascribed to the increase of hydroxyl groups on the skeleton surface. Hence, the supercritical modification method utilizing hexamethyldisilazane was also introduced to enhance the hydrophobic methyl groups on the aerogel’s surface. As a result, the obtained aerogels revealed superhydrophobicity with a contact angle of 155°. Meanwhile, the developed surface modification method did not lead to any significant changes in the pore structure resulting in the superhydrophobic aerogel with a high transparency of 77.2%. The proposed co-precursor approach and supercritical modification method provide a new horizon in the fabrication of highly transparent and superhydrophobic PMSQ aerogels. Full article