Fabrication of silane-grafted graphene oxide and its effect on the structural, thermal, mechanical, and hysteretic behavior of polyurethane

Effect of surface modification of graphene oxide with a reactive silane coupling agent on the mechanical properties and biocompatibility of acrylic bone cements

Carbon allotrope materials (i.e. carbon nanotubes (CNTs), graphene, graphene oxide (GO)), have been used to reinforce acrylic bone cement. Nevertheless, the intrinsic incompatibility among the above materials produces a deficient interphase. Thus, in this work, the effect of the content of functionalized graphene oxide with a reactive silane on the mechanical properties and cell adhesion of acrylic bone cement was studied. GO was obtained by an oxidative process on natural graphite; subsequently, GO was functionalized with 3-methacryloxypropyltrimethoxysilane (MPS) to enhance the interphase between the graphenic material and acrylic polymeric matrix. Pristine GO and functionalized graphene oxide (GO-MPS) were characterized physicochemically (XPS, XRD, FTIR, and Raman) and morphologically (SEM and TEM). Silanized GO was added into the acrylic bone cement at different concentrations; the resulting materials were characterized mechanically, and their biocompatibility was also evaluated. The physicochemical characterization results showed that graphite was successfully oxidized, and the obtained GO was successfully functionalized with the silane coupling agent (MPS). SEM and TEM images showed that the GO is composed of few stacked layers. Compression testing results indicated a tendency of increasing stiffness and toughness of the acrylic bone cements at low concentration of functionalized GO. Additionally, the bending testing results showed a slightly increase in bone cement strain with the incorporation of GO-MPS. Finally, all samples exhibited cell viability higher than 70%, which means that materials are considered non-cytotoxic, according to the ISO 10993-5 standard.

Preparation of Superhydrophobic Materials and Establishment of Anticorrosive Coatings on the Tinplate Substrate by Alkylation of Graphene Oxide

Corrosion of structural parts not only reduces the service life of the equipment but also causes safety accidents, so building a long-lasting anti-corrosion coating on its surface is the key to solving this problem. Under the action of alkali catalysis, n-octyltriethoxysilane (OTES), dimethyldimethoxysilane (DMDMS), and perfluorodecyltrimethoxysilane (FTMS) hydrolyzed and polycondensed co-modified graphene oxide (GO), modified to synthesize a self-cleaning superhydrophobic material fluorosilane-modified graphene oxide (FGO). The structure, film morphology, and properties of FGO were systematically characterized. The results showed that the newly synthesized FGO was successfully modified by long-chain fluorocarbon groups and silanes. FGO presented an uneven and rough morphology on the substrate surface, the water contact angle was 151.3°, and the rolling angle was 3.9°, which caused the coating to exhibit excellent self-cleaning function. Meanwhile, the epoxy polymer/fluorosilane-modified graphene oxide (E-FGO) composite coating adhered to the carbon structural steel's surface, and its corrosion resistance was detected by the Tafel curve and EIS impedance. It was found that the current density of the 10 wt% E-FGO coating (I_corr) was the lowest (1.087 × 10^-10 A/cm²), which was approximately 3 orders of magnitude lower than that of the unmodified epoxy coating. This was primarily due to the introduction of FGO, which formed a continuous physical barrier in the composite coating and gave the composite coating excellent hydrophobicity. This method might provide new ideas for advances in steel corrosion resistance in the marine sector.

Biological Effects, Applications and Design Strategies of Medical Polyurethanes Modified by Nanomaterials

Polyurethane (PU) has wide application and popularity as medical apparatus due to its unique structural properties relationship. However, there are still some problems with medical PUs, such as a lack of functionality, insufficient long-term implantation safety, undesired stability, etc. With the rapid development of nanotechnology, the nanomodification of medical PU provides new solutions to these clinical problems. The introduction of nanomaterials could optimize the biocompatibility, antibacterial effect, mechanical strength, and degradation of PUs via blending or surface modification, therefore expanding the application range of medical PUs. This review summarizes the current applications of nano-modified medical PUs in diverse fields. Furthermore, the underlying mechanisms in efficiency optimization are analyzed in terms of the enhanced biological and mechanical properties critical for medical use. We also conclude the preparation schemes and related parameters of nano-modified medical PUs, with discussions about the limitations and prospects. This review indicates the current status of nano-modified medical PUs and contributes to inspiring novel and appropriate designing of PUs for desired clinical requirements.

Three component synthesis of triazolo[1,2-a]indazole-trione and spiro triazolo[1,2-a]indazole-tetraones using GO/SiO2/Co (II)

In this study, a functionalized graphene oxide catalyst (GO/f-SiO₂/Co) was successfully synthesized by decorating the graphene oxide surface using the attachment of hybrid silane (silica/nitrogen) and chelation with Co (II). The catalyst has been characterized by Fourier Transform Infrared (FT-IR), powder X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), Raman spectra, Brunauer-Emmett-Teller (BET), and Thermal Gravimetric (TGA) analyses. The synthesized catalyst was used as an effective heterogeneous catalyst for the synthesis of triazolo[1,2-a]indazole-trione and spiro triazolo[1,2-a]indazole-tetraones derivatives under solvent-free conditions at 90 °C. The high thermal stability, corrosion resistance, and ability of the catalyst to recycle make the catalyst favorable. In addition, easy work-up procedure and short reaction time with high conversion yields (91-97%) are some benefits of the current method.

Synthesis and Characterization of Crosslinked Castor Oil-Based Polyurethane Nanocomposites Based on Novel Silane-Modified Isocyanate and Their Potential Application in Heat Insulating Coating

An isocyanate with trimethoxysilane groups at the side chains (IPDI-M) was synthesized via an addition between the mercaptopropyl trimethoxysilane groups (MPTMS) and IPDI tripolymer (IPDI-T). Then, silane grafted isocyanate as the functional hard segment, castor oil as the soft segment, poly (ethylene adipate) diol (PEA) as the chain extender, and MPTMS as an end-capping reagent were applied to form a series of organosilicon hybrid bio-based polyurethane (CPUSi). The effect of the IPDI-M contents on the thermal stability, mechanical properties, and surface properties of the resulting product was systematically investigated. Profit from the Si–O–Si crosslinked structures formed from MPTMS curing, the tensile strength, and Young’s modulus of the resulting products increased from 9.5 MPa to 22.3 Mpa and 4.05 Mpa to 81.59 Mpa, respectively, whereas the elongation at break decreased from 342% to 101%. The glass transition temperature, thermal stability, transparency, hydrophobicity, and chemical resistance were remarkably strengthened for the obtained organosilicon-modified polyurethane with the increasing MPTMS content. At the end of the work, the thermal insulation coating that was based on CPUSi and ATO can effectively block near-infrared rays, and the temperature difference between the inside and outside of the film reached 15.1 °C.

Bio-Based Polyurethane Foams with Castor Oil Based Multifunctional Polyols for Improved Compressive Properties

Currently, most commercial polyols used in the production of polyurethane (PU) foam are derived from petrochemicals. To address concerns relating to environmental pollution, a sustainable resource, namely, castor oil (CO), was used in this study. To improve the production efficiency, sustainability, and compressive strength of PU foam, which is widely used as an impact-absorbing material for protective equipment, PU foam was synthesized with CO-based multifunctional polyols. CO-based polyols with high functionalities were synthesized via a facile thiol-ene click reaction method and their chemical structures were analyzed. Subsequently, a series of polyol blends of castor oil and two kinds of castor oil-based polyols with different hydroxyl values was prepared and the viscosity of the blends was analyzed. Polyurethane foams were fabricated from the polyol blends via a free-rising method. The effects of the composition of the polyol blends on the structural, morphological, mechanical, and thermal properties of the polyurethane foams were investigated. The results demonstrated that the fabrication of polyurethane foams from multifunctional polyol blends is an effective way to improve their compressive properties. We expect these findings to widen the range of applications of bio-based polyurethane foams.