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The in situ confinement of nickel (Ni)‐iron (Fe) nanoparticles (NPs) in a polymer‐derived microporous silicon carboxynitride (Si−C−O−N)‐based support is investigated to stimulate superior oxygen evolution reaction (OER) activity in an alkaline media. Firstly, we consider a commercial polysilazane (PSZ) and Ni and Fe chlorides to be mixed in N,N‐dimethylformamide (DMF) and deliver after overnight solvent reflux a series of Ni−Fe : organosilicon coordination polymers. The latter are then heat‐treated at 500 °C in flowing argon to form the title compounds. By considering a Ni : Fe ratio of 1.5, face centred cubic (fcc) NixFey alloy NPs with a size of 15–30 nm are in situ generated in a porous Si−C−O−N‐based matrix displaying a specific surface area (SSA) as high as 237 m2 ⋅ g−1. Hence, encapsulated NPs are rendered accessible to promote electrocatalytic water oxidation. An OER overpotential as low as 315 mV at 10 mA ⋅ cm−2 is measured. This high catalytic performance (considering that the metal mass loading is as low as 0.24 mg cm−2) is rather stable as observed after an activation step; thus, validating our synthesis approach. This is clearly attributed to both the strong NP‐matrix interaction and the confinement effect of the matrix as highlighted through post mortem microscopy observations. [ABSTRACT FROM AUTHOR]

To improve the compatibility of ammonium polyphosphate (APP) with thermoplastic polyurethane (TPU), novel phosphorus containing polysilazane was used to microencapsulate APP (APP@SiNP) which was then used for flame retardant TPU. The influence of microencapsulation on the thermal decomposition, mechanical and flame retardant properties of TPU was investigated. The addition of APP@SiNP brought forward the onset thermal decomposition temperature (T5%) of the TPU, but improved the thermal stability of the char layer at high temperatures. The presence of APP@SiNP fillers tended to reduce the tensile strength and elongation at break of TPU, but the tensile strength and elongation at break of TPU/APP@SiNP -10.0 were still higher than those of TPU/APP-10.0, indicating that polysilazane was capable of improving the interfacial interaction between APP and the TPU matrix. Both TPU/APP@SiNP-7.5 and TPU/APP@SiNP-10.0 can achieve UL-94 V-0 level. The PHRR, THR, and TSP values of TPU/APP@SiNP-10.0 were 77%, 58%, and 70% lower than the pristine TPU, which were also better than TPU/APP-10.0. The superior flame retardant efficiency of APP@SiNP was attributed to its catalytic charring capacity and the formation of thermally stable char residues. Keywords: Flame retardance; Polysilazane; Ammonium polyphosphate; Smoke suppression [ABSTRACT FROM AUTHOR]

The development of new encapsulating coatings for flexible solar cells (SCs) can help address the complex problem of the short lifespan of these devices, as well as optimize the technological process of their production. In this study, new laminate-type protective composite coatings were prepared using a silicon oxynitride thin-film matrix obtained by curing the pre-ceramic polymer perhydropolysilazane (PHPS) through two low-temperature methods: (i) thermal annealing at 180 °C and (ii) exposure to UV radiation at wavelengths of 185 and 254 nm. Single-walled carbon nanotubes (SWCNTs) were used as fillers via dry transfer, facilitating their horizontal orientation within the matrix. The optical, adhesive, and structural properties of the matrix films and SiOxNy/SWCNT composite coatings, along with their long-term stability, were studied using Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, HR-SEM, spectral ellipsometry, and a progressive-load scratch test. In this work, the optical constants of PHPS-derived films were systematically studied for the first time. An antireflection effect was observed in the composites revealing their two-component nature associated with (i) the refractive index of the SiOxNy matrix film and (ii) the embedding of a SWCNT filler into the SiOxNy matrix. The curing method of PHPS was shown to significantly affect the resulting properties of the films. In addition to being used as protective multifunctional coatings for SCs, both SiOxNy/SWCNT composites and SiOxNy matrix films also function as broadband optical antireflective coatings. Furthermore, due to the very low friction coefficients observed in the mechanical tests, they show potential as scratch resistant coatings for mechanical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Ranging from industrial facilities to residential infrastructure, functional surfaces encompassing functionalities such as anti-fouling, fog collection, anti-corrosion, and anti-icing play a critical role in the daily lives of humans, but creating these surfaces is elusive. Bionic dewetting and liquid-infused surfaces have inspired the exploitation of functional surfaces. However, practical applications of these existing surfaces remain challenging because of their inherent shortcomings. In this study, we propose a novel functional slippery lubricated coating (FSLC) based on a simple blend of polysilazane (PSZ), silicone oil, and nano silica. This simple, nonfluorine based, and low-cost protocol promotes not only hierarchical micro-nano structure but also favorable surface chemistry, which facilitates robust silicone oil adhesion and excellent slippery properties (sliding angle: ∼1.6°) on various solid materials without extra processing or redundant treatments. The highly integrated competence of FSLC, characterized by robustness, durability, strong adhesion to substrates, and the ability for large-area preparation, render them ideal for practical production and application. The proposed FSLC holds outstanding application potentials for anti-fouling, self-cleaning, fog collection, anti-corrosion, and anti-icing functionalities. [ABSTRACT FROM AUTHOR]

Although various aerogels with electromagnetic wave (EMW) absorbing properties have been extensively explored, the development of aerogels with excellent wave absorption performance, low density, and great heat resistance has still met profound challenges. Herein, polysilazane hybrid phenolic resin aerogels (PRVS aerogels) were prepared using the vinyl addition reaction of polysilazane and cross‐linking reaction between polysilazane and phenolic resin. A SiOCN ceramic aerogel with multistage pore structure was prepared via a simple and quick freeze‐drying method and polymer‐derived ceramic (PDC) methods. The SiOCN ceramic aerogels exhibited low density (0.15–0.27 g/cm3), good heat‐shielding (thermal conductivity in the range of 0.03–0.04 W/(m·K)), and excellent wave absorption performance (i.e., RL was about –31.6 dB@16.48 GHz and EAB was 3.85 GHz when the thickness of the ceramic aerogel was 1.2 mm). Hence, the ceramic aerogel absorbing materials could meet the requirements of "wide absorption bandwidth, strong reflection loss, lightweight and thi thickness". Moreover, the mechanism of low weight, heat insulation, and wave absorption properties of the aerogels were also investigated. We believe this work is of great significance in ceramic aerogels prepared by traditional polymers, which may provide new opportunities for new ceramic aerogels with applications ranging from EMW absorption to aerospace and information technology. [ABSTRACT FROM AUTHOR]

As an excellent ceramic precursor, polysilazane could be cured at low temperatures, which provided a possibility for the preparation of thermal protective coatings for carbon fibers reinforced polymer (CFRP) composites. Hollow glass microspheres with low thermal conductivity were introduced into coatings. Meanwhile, the thermal protection effect of coatings was further enhanced. The dispersion and stability of hollow glass microspheres in polysilazane resin were improved by alkali treatment and grafting coupling agent. Results showed that the stability could be maintained within 2 h, which was feasible in engineering applications. Static thermal tests and hygrothermal aging tests were designed to evaluate the thermal insulation effect of the coating. After 10 min of heat assessment in air atmosphere, the three-point bending performance of coated samples was better than that of uncoated samples. The protection effect was more obvious when the test temperature was higher than the glass transition temperature of carbon fibers reinforced epoxy composites. The bending strength of the coated sample at 270 °C was 743.9 ± 11.9 MPa, which was higher than that of the uncoated sample at 210 °C (743.4 ± 22.3 MPa). According to the result of 5 cycles hygrothermal aging test, the negative effect of acid environments was greater than that of alkali or water. Dynamic thermomechanical analyzer results showed that the coating effectively prevented the damage of water, alkali, or acid environments on the epoxy resin. The above results indicated that the existence of polysilazane and hollow glass microsphere coating systems could further expand the high-temperature application of CFRP. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A hybrid coating based on polyorganosilazane (Durazane® 1800) combined with 3-glycidyloxypropyltrimethoxysilane (GPTMS) was successfully synthesized to improve the corrosion resistance of the AA2024-T3 aluminum alloy. The polymers were cross–linked with the addition of tetra-n-butylammonium fluoride (TBAF), and the hybrid coatings were deposited on aluminum substrates by dip coating and dried at 120 °C. Crack-free films with a thickness of 13 μm were obtained. Field emission electron microscopy (FESEM) analysis indicated that the synthesized hybrid films were smooth, homogenous, and devoid of cracks. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) studies demonstrated that the intensity of the Si–N–Si peak was maintained, showing that the backbone of the polysilazane was preserved after the addition of GPTMS. Nuclear magnetic resonance (NMR) spectroscopy indicated that glycidoxypropyl groups were still present in the Si–O–N network of the modified polysilazane. Contact angle measurements indicated that the hybrid coatings were hydrophobic, with a measured contact angle of 93 ± 6°. The electrochemical results confirmed that the synthesized hybrid coatings improved the corrosion resistance of the aluminum substrate in 3.5 wt% NaCl solution. This suggest that the modified polyorganosilazane coating is an effective solution for developing anti-corrosive coatings on metal substrates, offering excellent adhesion strength and good scratch resistance.

The silicone rubber with high strength and high-temperature resistant properties was prepared via a dual-vulcanizer system based on the raw silicone rubber containing of both vinyl group and hydroxyl group. The effect of the dosage of cross-linker KH-CL, the processing way of silicon oxide and the antioxidant on the properties of silicone rubber were investigated. The optimum recipe was confirmed. It’s shown that the optimum dosage of KH-CL is 3phr, which is benefit for the vulcanization and the suppression of the main chain of silicone rubber. The silazane treated silicon oxide and home-made antioxidant are the optimum additives of the silicone rubber. The prepared silicone rubber shows outstanding heat-resistant properties at 350 ℃ for a short time and 300 ℃ for a long time.

Polysilazane-based coatings exhibit excellent mechanical properties and chemical resistance, but thermal curing limits their range of applications. Therefore, the aim of the study was to evaluate the more resource-efficient curing of polyorganosilazane-based coatings on a stainless-steel substrate by photo-induced thiol-ene “click” reaction at room temperature compared to the conventional thermally induced polymerization using a radical initiator. As expected crosslinking at higher temperatures led to the formation of a pronounced Si-O-Si network. However, crosslinking via UV radiation at room temperature suppressed the incorporation of oxygen remarkably also after a subsequent additional treatment at 135 °C in air. Both the chemical stability of the layers cured by means of UV radiation and the mechanical properties are comparable to those of the thermally crosslinked coatings. Therefore, curing using UV radiation at low temperatures is a suitable alternative method for producing protective coatings on substrates with limited thermal stability.

Trimethylsilyl‐substituted polysilazanes were designed and successfully synthesized. They were used to fabricate high‐purity stoichiometric Si3N4 ceramics through pyrolysis process. Trimethylsilyl groups improved the stability of polysilazanes and easily escaped during pyrolysis, which effectively reduced oxygen and carbon content in the final polymer‐derived Si3N4. The C content of Si3N4 ceramic was below 0.06 wt%, and the O content was below 1.2 wt%. The Si3N4 ceramics remained amorphous up to 1400°C, yet they were completely transformed into α‐Si3N4 at 1500°C. Synergistic effect from low oxygen and carbon content contributed to highly stable amorphous state of Si3N4 till high temperatures. This amorphous Si3N4 ceramics could be used in cutting‐edge technology where high purity is compulsory. [ABSTRACT FROM AUTHOR]

The precursors of polysilazane (PSZ) with different weights were dissolved in xylene to obtain the spinning solution with different concentration. PSZ spinning solution was converted to SiCN(O) fibers by dry spinning, ultraviolet (UV) irradiation cross-linking, and pyrolysis at 1 100 °C. The rheological property of PSZ spinning solution and the UV irradiation cross-linking process of PSZ fibers were investigated by rotational rheometer, FTIR, XPS, SEM and TG. The composition, structure and properties of PSZ fibers and SiCN(O) fibers before and after irradiation were also characterized. The results show that the PSZ spinning solution with the mass fraction of 87% has shear thinning behavior at room temperature, which belongs to the pseudoplastic fluid and has excellent dry spinning performance. The ceramic yield of PSZ fibers increases by 30. 8% compared with the green fibers after 7 h cross-linking under UV irradiation with wavelength of 185 nm. This research has certain exploration significance for the new spinning process of PSZ and the curing treatment of PSZ fibers. [ABSTRACT FROM AUTHOR]

In this study, we investigated the tunable porous structure of SiCN(O)-derived ceramic aerogels by changing the molecular structure of the polysilazanes from linear to branched. We also studied the effect of molecular structure on the thermal insulation properties of ceramic aerogels. As the percentage of branched molecular structure in the polysilazane precursor increased, the internal microscopic pore structure of the aerogels changed from macroporous to mesoporous. The specific surface areas and pore volumes of the ceramic aerogels prepared with different precursors increased after pyrolysis at 1000 °C, ranging from 3.7 to 255.9 m2/g and 0.01–0.36 cm3/g, respectively. The corresponding thermal conductivities increased slightly as the aerogels contracted after pyrolysis. The low thermal conductivity (0.046 W/(m·K) at minimum) can be attributed to the decrease in pore size caused by adjusting the precursor structure, which limits the thermal conduction of gas in the porous aerogel materials. [ABSTRACT FROM AUTHOR]

Abstract In this study, a novel colorless and transparent polysilazane (PSZ) with excellent spinnability was facilely synthesized via the thermal polymerization of silazane oligomer at 330℃. The silazane precursor was fabricated by one‐step copolycondensation of methyldichlorosilane (CH3SiHCl2) and dimethyldichlorosilane ((CH3)2SiCl2) in various ratios at 0℃ without catalyst during the reaction. The chemical composition, molecule structure, molecular weight and ceramic yield of PSZ were investigated by gel permeation chromatography (GPC), Fourier transform infrared (FT‐IR), thermogravimetric analysis (TGA) and pyrolysis chromatography‐mass spectrometry (PY‐GC/MS). The optimized novel transparent melt‐spinnable PSZ was a colorless and transparent brittle solid with a Mw = 14,231 and a melting point of 100℃, which was prepared with an optimal molar ratio of raw materials at 1.9:1 (CH3SiHCl2: (CH3)2SiCl2). Fibers with various diameters were spun using a homemade melt spinning setup at 90–120°C. The obtained PSZ showed outstanding spinnability, and the prepared continuous fibers exhibited a uniform diameter (10–80 microns) and a smooth surface up to 1000 meters long. In addition, possible polymerization mechanisms of PSZ were also discussed. The PSZ showed the excellent rheological properties in melt‐spinning as a potential precursor for Si3N4 fibers. The novel optically transparent polysilazane material also have great potential applications in optical technology and engineering.

This work developed a method to enhance the durability of anti‐icing performance of a coating to endure abrasion and UV exposure, through grafting functional polydimethylsiloxane (PDMS) to TiO2 particles and further reacting with polysilazane (PSZ) pre‐polymer. This method remarkably improved the anti‐icing properties of PSZ‐based coatings evaluated by freezing delay time and ice removal shear strength. After either surface abrasion for 50 cycles or UV exposure for 100 h, the modified coatings exhibited ice shear strength increase by only 10.44 and 6.44 kPa respectively, significantly lower comparing to that of the coatings containing 30% TiO2 with no PDMS modification (29.69 and 11.88 kPa, respectively). Such strengthened durability of anti‐icing performance is attributed to the PDMS molecules bridging PSZ rigid segments and TiO2 compositions, which formed a hydrophobic cross‐linking network structure. The durable anti‐icing technique developed herein shall appeal to many outdoor applications of facilities and infrastructures. [ABSTRACT FROM AUTHOR]

Antiadhesive coatings have been extensively studied owing to their wide applications in biology, environment, and energy. However, developing a mechanically robust coating with broad-spectrum antiadhesion properties remains challenging. Herein, a novel strategy for preparing hard yet flexible and self-adaptive zwitterionic polysilazane coatings with broad-spectrum antiadhesion properties (anti-biofouling, anti-liquid adhesion, and anti-scaling) is proposed. The coatings are prepared by combining polysilazane with a telomer (FT) consisting of a low-surface-energy fluorine motif and hydrolysis-induced zwitterions. Before Si─OH generation in polysilazane, the fluorine motif drives the zwitterionic precursor to enrich on the surface, generating a zwitterionic layer following pre-hydrolysis. This unique design prevents the coatings from swelling in water, allowing them to adapt to diverse environments. The fluorine motif can orient toward the surface of air, providing anti-liquid adhesion capabilities, whereas the zwitterions orient underwater to endow anti-biofouling, anti-liquid adhesion, and anti-scaling capabilities. The highly cross-linked network toughened by FT contributes to the high hardness (up to 7H) and good flexibility of the coating. The chemical bonding between the coating and substrates ensures their strong adhesion (≈2.06-7.67 MPa). This study contributes to the design of mechanically robust broad-spectrum antiadhesive coatings applicable in marine industries, optical devices, pipeline transportation, and other fields., (© 2024 Wiley‐VCH GmbH.)

This paper reports a route to suppress the grain growth in silicon carbide (SiC) during its sintering by combining it with polysilazane (PSZ). SiC was mixed with PSZ in a 1:1 weight ratio and sintered at 1600, 1700, and 1800 °C in a hot-pressing furnace. A satisfactory density was obtained at sintering temperatures > 1600 °C. The grain sizes of the SiC/PSZ composites sintered at 1700 and 1800 °C were 112 and 125 nm, respectively. The grain shape of the SiC/PSZ composite sintered at 1700 °C was circular and mainly similar to the initial shape of the SiC powder. Grain shape accommodation was observed at a sintering temperature of 1800 °C. It is suggested that different sample shapes were affected by different liquid phase formations. Silicon oxynitride (Si2N2O) was formed and played an important role in densification and microstructure generation.

In this work, high strength and high wear‐resistant titanium matrix composites (TMCs) reinforced with in situ TiC derived from pyrolysis of polysilazane (PSZ) are fabricated successfully. The processing technology is developed with a novel powder metallurgy method combining solution‐assisted wet mixing and pressureless sintering. The effects of PSZ addition on the microstructure, hardness, mechanical properties, and tribological properties are systematically studied. The TMCs possess better comprehensive properties compared to conventional ex situ methods. The pyrolysis of PSZ leads to the formation of TiC particles and N, Si atoms solid‐solution in the Ti matrix. The microstructure of the composites is homogenous and fine‐grained. The average grain size of α‐Ti decreases significantly from 106.1 µm of pure Ti to 37.2 µm of the 1.5 wt% PSZ/Ti composite. Among these TMCs, the 1.5 wt% PSZ/Ti composite displays comprehensively excellent mechanical properties with the ultimate tensile strength (UTS) of 711 MPa, yield strength (YS) of 568 MPa, and elongation (EL) of 8.0%. In addition, the composite possesses a high wear resistance with a low specific wear rate of 0.355 × 10−12 m3 N−1 m−1 under constant condition (0.03 m s−1, 2N). [ABSTRACT FROM AUTHOR]

This study presents an efficient anticorrosive coating based on an organic-inorganic hybrid polymer composed of methyl methacrylate, styrene, tert-butyl acrylate, and vinyl polysilazane. The synthesized resin exhibits excellent thermal resistance and stability, as confirmed by thermogravimetric analysis (TGA). Additionally, leveraging the resin's highly alkaline nature, cerium oxide (CeO 2) nanoparticles were doped in situ within the polymer matrix. The hybrid resins were subsequently applied to mild steel panels using a dip-coating technique. The resulting coatings are transparent, flexible, thin, pore-free, and possess low surface roughness (<2.62 nm), along with good thermal stability (>350 °C). Their remarkable anticorrosive performance and durability are attributed to forming a highly crosslinked acrylic-polysilazane network, combined with a cerium oxide protective barrier layer that adheres to the substrate. Furthermore, the cerium ions suppress both cathodic and anodic corrosion reactions, enhancing the corrosion resistance. Notably, the coating system containing 2 wt% cerium achieved a high impedance value of 106 Ω cm2, corresponding to a corrosion rate of 0.112 × 10−5 mm/year. This study demonstrates that these acrylic-vinyl polysilazane coatings, incorporating ceria as a corrosion inhibitor, offer a promising alternative to conventional protection systems. [Display omitted] • Development of acrylic-vinyl polysilazane copolymers to be used as anticorrosive coatings. • In-situ generation of cerium oxide in the resin leveraging the alkaline nature of the resin. • Formation of a cerium oxide barrier with the dense polymer coating, onto the substrate. • Transparent and pore-free coatings with outstanding anticorrosive properties, with enhanced durability. [ABSTRACT FROM AUTHOR]

Pd-containing precursor has been synthesized from palladium acetate and poly(vinly)silazane (Durazane 1800) in an ice bath under an argon atmosphere. The results of ATR-FTIR and NMR characterizations reveal the chemical reaction between palladium acetate and vinyl groups in poly(vinyl)silazane and the hydrolyzation reaction between –Si–H and –Si–CH=CH2 groups in poly(vinyl)silazane. The palladium nanoparticles are in situ formed in the synthesized precursors as confirmed by XRD, XPS, and TEM. Pd- and Pd2Si-containing SiOCN ceramic nanocomposites are obtained by pyrolysis of the synthesized precursors at 700 °C, 900 °C–1100 °C in an argon atmosphere. The pyrolyzed nanocomposites display good catalytic activity towards the dry reforming of methane. The sample pyrolyzed at 700 °C possesses the best catalytic performance, which can be attributed to the in situ formed palladium nanoparticles and high BET surface area of about 233 m2 g−1. [ABSTRACT FROM AUTHOR]

Silicones are typically cured at room temperature by means of metal catalyst such as tin or platinum. When networks are formed, the catalyst becomes unrecoverable, which is of economic as well as environmental concern. Very few methods for producing metal catalyst‐free room‐temperature‐vulcanized (RTV) silicones exist and require conditions unavailable in industrial settings. Through the study of organic polysilazane (PSz) reactivity with simple alcohols by nuclear magnetic resonance, an unexpected fragmentation preference is discovered for breaking the SiN bond rather than the SiH; thereby, casting a new light on the fragmentation mechanism of PSzs. Utilizing the PSz fragmentation as a silyl ether coupling agent for multifunctional carbinol silicones, a method of producing catalyst‐free RTV silicone networks at ambient conditions is presented. These silicone networks are proven chemically similar to a standard condensation‐cured silicone and stoichiometric variations of PSz content demonstrate adjustable network properties. [ABSTRACT FROM AUTHOR]

Silicon dioxide thin films are a promising alternative to protective glass in solar cells. In this work, one-layer and four-layer thin films of a perhydropolysilazane (PHPS) were spin-coated from solution in dibutyl ether and cured by exposure to moderate temperatures or ultraviolet (UV) light to obtain glassy SiOx layers. Optical and morphological properties as well as their long-term stability were studied using XPS, FTIR, UV-Vis spectroscopy, and SEM microscopy with EDX analysis. The results showed that the process of converting PHPS layers to SiOx continues after the completion of the curing procedure for both methods. However, the composition of the thermally cured films is similar to silicon oxide, while the UV-cured samples demonstrate a composition similar to silicon dioxide due to differences in the reactions occurring during the curing process. The prolonged transformation process opens up possibilities for creating self-improving protective coatings based on PHPS. [ABSTRACT FROM AUTHOR]

In this study, a conductive Si/C/N/Ni nanocomposite was prepared using phenyl-substituted polysilazane and nickelocene (NiCp 2) as precursors. Ni-related nanoparticles were uniformly distributed throughout the Si/C/N/Ni nanocomposite without aggregation because of the large number of nitrogen atoms in the silsesquiazane used as a precursor of the matrix. In addition, the nickel silicide crystalline phase and turbostratic carbon phase grew in the matrix of the Si/C/N/Ni nanocomposite at low temperatures because NiCp 2 acted as a catalyst. Moreover, NiCp 2 contributed to the increase in the turbostratic carbon crystallinity through the dehydrogenation reaction, resulting in an improved electrical conductivity of the Si/C/N/Ni nanocomposite. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of high-temperature-resistant coatings is crucial, which demands a new adhesive resin owing to harsh service conditions. In this work, the structural evolution and basic performance of three different polysilazanes with a Si–N backbone are studied, which is further compared to a typical silicone resin with a Si–O backbone. Experimental results show that polysilazanes with different structures undergo a two-step oxidation process with a residual weight higher than 77% in comparison to the one-step degradation of silicone with a weight loss higher than 47% at 800°C under flowing air atmosphere. Additionally, the decrease in thickness of polysilazane-resin coating is below 50%, while that of the silicone-resin coating is higher than 77%, which affords a crack- and defect-free morphology in polysilazanes and blistering and particle aggregation in the silicone after a temperature treatment at 800°C. Thus, our study demonstrates that polysilazanes are potential alternative choices as resin adhesives for high-temperature-resistant coatings rather than silicone-based resins, in extremely harsh conditions. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a novel colorless and transparent polysilazane (PSZ) with excellent spinnability was facilely synthesized via the thermal polymerization of silazane oligomer at 330℃. The silazane precursor was fabricated by one‐step copolycondensation of methyldichlorosilane (CH3SiHCl2) and dimethyldichlorosilane ((CH3)2SiCl2) in various ratios at 0℃ without catalyst during the reaction. The chemical composition, molecule structure, molecular weight and ceramic yield of PSZ were investigated by gel permeation chromatography (GPC), Fourier transform infrared (FT‐IR), thermogravimetric analysis (TGA) and pyrolysis chromatography‐mass spectrometry (PY‐GC/MS). The optimized novel transparent melt‐spinnable PSZ was a colorless and transparent brittle solid with a Mw = 14,231 and a melting point of 100℃, which was prepared with an optimal molar ratio of raw materials at 1.9:1 (CH3SiHCl2: (CH3)2SiCl2). Fibers with various diameters were spun using a homemade melt spinning setup at 90–120°C. The obtained PSZ showed outstanding spinnability, and the prepared continuous fibers exhibited a uniform diameter (10–80 microns) and a smooth surface up to 1000 meters long. In addition, possible polymerization mechanisms of PSZ were also discussed. The PSZ showed the excellent rheological properties in melt‐spinning as a potential precursor for Si3N4 fibers. The novel optically transparent polysilazane material also have great potential applications in optical technology and engineering. [ABSTRACT FROM AUTHOR]

The in situ confinement of nickel (Ni)-iron (Fe) nanoparticles (NPs) in a polymer-derived microporous silicon carboxynitride (Si-C-O-N)-based support is investigated to stimulate superior oxygen evolution reaction (OER) activity in an alkaline media. Firstly, we consider a commercial polysilazane (PSZ) and Ni and Fe chlorides to be mixed in N,N-dimethylformamide (DMF) and deliver after overnight solvent reflux a series of Ni-Fe : organosilicon coordination polymers. The latter are then heat-treated at 500 °C in flowing argon to form the title compounds. By considering a Ni : Fe ratio of 1.5, face centred cubic (fcc) Ni x Fe y alloy NPs with a size of 15-30 nm are in situ generated in a porous Si-C-O-N-based matrix displaying a specific surface area (SSA) as high as 237 m 2  ⋅ g -1 . Hence, encapsulated NPs are rendered accessible to promote electrocatalytic water oxidation. An OER overpotential as low as 315 mV at 10 mA ⋅ cm -2 is measured. This high catalytic performance (considering that the metal mass loading is as low as 0.24 mg cm -2 ) is rather stable as observed after an activation step; thus, validating our synthesis approach. This is clearly attributed to both the strong NP-matrix interaction and the confinement effect of the matrix as highlighted through post mortem microscopy observations., (© 2024 Wiley-VCH GmbH.)

Polysilazane and platinum were adopted to enhance the thermal stability of silicone rubber. The effect and mechanism of polysilazane and platinum on enhancing thermal stability were investigated via thermogravimetry, scanning electron microscopy-energy dispersive X-ray spectrometry, thermogravimetry-Fourier transform infrared spectrometry, and Fourier transform infrared spectrometry. Remarkable synergism between polysilazane and platinum was found in enhancing thermal stability of silicone rubber. When 1.34 wt% polysilazane and 8 ppm platinum were added, the degradation temperatures were elevated. Furthermore, the thermal residues of silicone rubbers were increased from 30–45 to 66–76 wt%, and maximum degradation rates were reduced from 8.81–15.8 to 4.55–5.02 wt%/min. Besides, silicone rubber demonstrated excellent shape retention at high temperature in the presence of polysilazane and platinum. The mechanism may be that platinum cooperated with polysilazane and efficiently catalyzed radical crosslinking between polysilazane and silicone chains. As a result, a tightly crosslinked network was developed, and degradation of silicone rubber was suppressed. [ABSTRACT FROM AUTHOR]

Silicon and carbon containing non-oxide ceramics, such as SiC, SiCN, SiBCN, derived from polymeric precursors show outstanding resistance towards creep and oxidation at high temperatures and harsh atmospheric conditions. These polymer derived ceramics are potential materials for application as protective coatings on carbon and SiC based composites. In the current investigation, a commercially available polyvinylsilazane polymer was doped with molecular source of Ti, crosslinked and pyrolyzed in nitrogen atmosphere, and the evolution of phase and nanostructure was studied. The pyrolyzed SiTiCNO ceramic hybrids appeared predominantly amorphous up to 1000 °C. Exceptionally homogeneous distribution of anatase TiO 2 nanocrystals in the size range of 2–12.5 nm was observed throughout the SiCN matrix on high temperature annealing. Such SiCN–TiO 2 nanocomposites exhibit enhanced oxidation resistance till 1400 °C. The paper demonstrates easy fabrication of the ceramic nanocomposite, which promise application in high temperature barrier coatings and structural components due to its excellent crystallization and oxidation resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dense ceramic coating effectively improves soft magnetic performance. • The resistivity of SMCs can be significantly enhanced through the PSZ modification. • 0.5 wt% of PSZ achieved the optimal soft magnetic performance. • The interaction between PSZ and silicone resin enhances the thermal stability of the resin. The coatings play a crucial role in enhancing the performance of soft magnetic composites (SMCs). This study aims to create coatings for Fe-Ni-Mo SMCs using polysilazane (PSZ) as the precursor. The transformation mechanism of the PSZ/resin mixture is studied by analyzing functional groups and chemical bonds at various temperatures. During the self-polymerization process of PSZ at 350 °C, N–H, C = C–H, Si-H bonds, –CH 3 , and Si-CH 3 groups undergo crosslinking reactions to form C–C and Si-N bonds. When the temperature reaches 600 °C, PSZ polymer cleavage, O-Si-C and Si-N-Si bond dominate in the coating. Additionally, PSZ can effectively enhance the heat resistance of silicone resin through its reaction with Si-OH groups, which has a significant effect on increasing the resistivity of SMCs and reducing high frequency core loss. Optimizing the PSZ content to 0.5 wt% enhances the magnetic properties of Fe-Ni-Mo SMCs, resulting in a μ e of 74.0 at 100 kHz and a corresponding core loss (P cv) of 547.7 mW/cm3 at 100 kHz/100 mT. The findings provide valuable insights for optimizing PSZ content to improve magnetic performance in SMCs. [ABSTRACT FROM AUTHOR]

The effect of polysilazane on the densification and mechanical properties of SiCf/SiC composites was examined thoroughly. The polysilazane was infiltrated into the fiber area, followed by pyrolysis at 1450°C for 4 h in an argon atmosphere. Furthermore, the SiC fabrics contain the pyrolyzed polysilazane was infiltrated by β-SiC slurry and sintered at 1750°C for 2 h in an argon atmosphere. The density of SiCf/SiC composites with and without the addition of polysilazane was 2.65 and 3.05 g/cm3, respectively. The pores in the fiber area were observed for the SiCf/SiC composites with the addition of polysilazane. However, the fine-grained size in the matrix area was obtained by the addition of polysilazane. The average grain size of the SiCf/SiC composite with and without the addition of polysilazane was 253 and 740 nm, respectively. Indeed, the hardness of the matrix area for SiCf/SiC composites with the addition of polysilazane (31.6 ± 1.8 GPa) was higher compared to SiCf/SiC composites without polysilazane (27.4 ± 1.6 GPa).

A single quadrupole mass spectrometer coupled measuring setup was developed for the investigation of the helium transmission rate (HeTR) of SiOx-coated polyethylene terephthalate (PET) barrier films. The setup allows the pressure-less and timeresolved measurements of the helium permeation at transient and steady-state conditions. Whereas standard water vapour transmission rate (WVTR) experiments took extended test times (in the range of several days), HeTR measurements were finished after 1 h. For the material system investigated here, an excellent linear correlation of WVTR and HeTR was proven over two orders of magnitude (regarding WVTR). Experiments with application of different strain loads on the coated films revealed a significant increase of both, HeTR and WVTR. Scanning electron microscope (SEM) measurements evidenced multiple ruptures of the SiOx coating depending on the applied strain and initial thickness of the SiOx layer. Considering virgin barrier films and strain-ruptured barrier films, a good correlation of WVTR and HeTR was shown. [ABSTRACT FROM AUTHOR]

In this work, the formation of transient microporosity during the polymer-to-ceramic conversion in polymer-derived ceramics was studied using a commercially available poly(vinyl)silazane precursor which was modified with divinylbenzene (DVB) as linker molecule during crosslinking. After pyrolysis treatments between 400 and 700 °C, the resulting materials not only showed distinct changes in elemental composition and structural features upon introduction of the linker molecule, but also a shift in micropore size, e.g. shifting from 0.84 nm to 0.70 nm after pyrolysis at 600 °C. Due to hindrance of transamination reactions in the low-temperature region, the nitrogen content in linker-containing samples was significantly higher, leading to a different composition of micropore-forming entities and, in case of the system studied, to smaller pores. These findings are a first step towards the clarification of the mechanisms leading to the pore formation in PDCs during pyrolytic conversion, which is essential for their use in prospective applications. [ABSTRACT FROM AUTHOR]

Ceramic matrix composites usually utilize carbon or ceramic fibers as reinforcements. However, such fibers often expose a low ductility during failure. In this work, we follow the idea of a reinforcement concept of a ceramic matrix reinforced by refractory metal fibers to reach pseudo ductile behavior during failure. Tungsten and molybdenum fibers were chosen as reinforcement in SiCN ceramic matrix composites manufactured by polymer infiltration and pyrolysis process. The composites were investigated with respect to microstructure, flexural- and tensile strength. The single fiber strengths for both tungsten and molybdenum were investigated and compared to the strength of the composites. Tensile strengths of 206 and 156 MPa as well as bending strengths of 427 and 312 MPa were achieved for W/SiCN and Mo/SiCN composites, respectively. The W fiber became brittle across the entire cross section, while the Mo fiber showed a superficial, brittle reaction zone but kept ductile on the inside. [ABSTRACT FROM AUTHOR]

Ceramic aerogels possess intriguing thermophysical properties which make them excellent candidates for high temperature thermal insulators. However, their properties can degrade at high temperature because of crystallization phenomena or because of densification (causing a sensible reduction of their specific surface area and porosity). The polymer derived ceramic (PDC) route is a relatively new way of developing ceramic aerogels. Several aspects influence the properties of the final product when dealing with preceramic polymers, among them their chemical composition and molecular architecture. In this work, we investigated the possibility of producing aerogels belonging to the SiCN system from polysilazanes mixtures, namely perhydropolysilazane (PHPS) and a methyl/vinyl-containing polysilazane, namely Durazane 1800®, thus changing the C/Si ratio of the amorphous pyrolyzed products. It is shown that the chemical composition of the ceramic aerogel affects the main properties of the porous materials, such as thermal stability and specific surface area (SSA). Results show that the presence of carbon in the aerogels inhibits crystallization of Si 3 N 4 up to 1600 °C in N 2 and allows to maintain a SSA of ~90 m2/g up to this temperature. [ABSTRACT FROM AUTHOR]

A hybrid cyanate ester resin containing polysilazane was prepared via the prepolymerization of bisphenol-A dicyanate ester monomer (BADCy) in the presence of polysilazane (PSZ) under low temperature conditions in a short period of time. Fourier transform-infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy reveal that the polymerization reaction of BADCy can be carried out in the presence of PSZ to obtain a hybrid resin below 100°C and polymethylsilazane (PHS) exhibits an improved prepolymerization effect when compared to polydimethylsilazane (PMS). FT-IR spectroscopy and gel permeation chromatography (GPC) showed that the prepolymerization degree of the PHS/BADCy resin increased upon increasing PHS mass fraction from 0 to 12 wt%, polymerization temperature from 60 to 100°C and polymerization time from 0 to 4 h. The PHS/BADCy hybrid resins samples were prepared and their process properties were investigated by rheometry and Differential scanning calorimetry (DSC). The results indicated that their viscosity was <10 Pa.s in the temperature range of 60–130°C, and the initial curing temperature and curing exothermic enthalpy were 121.9°C and 358.9 J/g, respectively. Furthermore, the cured PHS/BADCy resin possesses excellent thermal and mechanical properties, the 5% weight loss temperature (Td5) and glass transition temperature (Tg) were 424–441°C and 273–282°C, respectively. The cured PHS/BADCy resin with 4 wt% PHS showed the highest flexural strength of 146 MPa and flexural modulus of 4.1 GPa. [ABSTRACT FROM AUTHOR]

Manufacturing complexity and poor machinability hinder the preparation of complex-shaped ceramic composites. Three-dimensional printing can overcome this difficulty. Herein, we report a type of photocurable preceramic resin containing SiO 2 nanoparticles (up to 20 wt% of polymer), which do not affect the photocurability of the preceramic resin, and a small amount of SiC nanofibres (1 wt%). We successfully printed precise green bodies with a complex shape by digital light processing and converted them into ceramic composites via pyrolysis at 1300 °C under a N 2 atmosphere. The introduction of SiO 2 and SiC into the ceramic composites led to reduced weight loss of the composites during pyrolysis and a decrease in their porosity and enhancement in their mechanical properties after pyrolysis. The properties of the printed samples pyrolysed at different ramping rates were compared, and the effects of the microstructure on the mechanical properties of the composites were investigated. [ABSTRACT FROM AUTHOR]

As a new method for producing dense ceramics with complex structures, digital light processing 3D printing technology has received considerable attention when applied to polymer-derived ceramics. In this study, using acrylate monomers, we developed a material system to modify the polysilazane preceramic polymers. Furthermore, during photopolymerization, the photocuring thickness was tuned using carbon nanotubes as light absorbers, thus improving the printing accuracy. The green body was printed and subsequently pyrolyzed to obtain the SiCN ceramic. We then managed to completely maintain the printed structure with uniform shrinkage being observed in all directions. The printed ceramic microstructures, denoting pyrolysis-induced microstructural changes, were characterized using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. This study paves the way for developing new approaches to obtain ultra-light and high-strength microwave-absorbing components that are suitable for aerospace applications by combining the SiCN ceramics of the unique dielectric properties with 3D printing technology to produce dense ceramics with periodic 3D structures. [ABSTRACT FROM AUTHOR]

Due to their unique physicochemical properties, polysilazanes exhibit excellent performance when combined with some resin matrixes, which had drawn great research attention. In this article, polyurethane (PU) was firstly prepared by polytetrahydrofuran glycol, isophorone diisocyanate, and 1,4-butanediol as main materials. Then, the prepared PU was blended with polysilazane by mixing the two solutions together, which was cured to films via dip-coating method at room temperature. The structure, thermal stability, and surface properties of the composite coatings were investigated by Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The results demonstrated that after modification with polysilazane, the heat resistance, hydrophobicity, and mechanical property of the PU coatings were improved. When the content of polysilazane was 6 wt%, the mechanical property of the composite films was optimized, with a maximum tensile strength of 25.7 MPa and elongation at break of 797%. Meanwhile, the water contact angle of the composite film was 107° and the water absorption reached a minimum of 2.1%, which showed improved hydrophobicity and water resistance. [ABSTRACT FROM AUTHOR]

The molecular structure of polymer has a great influence on the physical and chemical properties of polysilazane and the properties of ceramics pyrolyzed from the polysilazane. The polysilazane with reticulating molecular structure has good performance generally. The performance of the precursor can be effectively improved by reasonable molecular structure design and control of the synthesis process. In this paper, a reticulating polysilazane PSZ-M with outstanding meltability and solubility were synthesized via an aminolysis reaction between dichloromethylsilane (DCMS) and hexamethyldisilazane (HMDZ), and using the melamine as additive. The properties and the ceramization process of PSZ-M, as well as the molecular structure and properties of derived SiCN ceramic, were well studied. The melamine can be introduced via the dehydrogenation reaction between N–H and Si–H. The ceramics yield was enhanced to 63.18% at 900 °C after the introduction of melamine. The SiCN ceramics derived from the PSZ-M can remain amorphous when pyrolyzed below 1400 °C, the crystal phase of SiC, SiN4 were detected for 1500 °C treated samples. The using of melamine as an additive to synthesis polysilazanes has led to the development of a convenient approach for constructing polysilazanes with reticulating structure and ideal performance, which supports a strategy for the structure design of preceramic polymers. [ABSTRACT FROM AUTHOR]

The SiO2/PSN core-shell microspheres were prepared via an emulsion reaction combined with the polymer-derived ceramics (PDCs) method using polysilazane (PSN) in situ polymerization on the surface of SiO2 modified by silane coupling agents MPS, followed by pyrolysis process to obtain SiO2/SiCN core-shell ceramic microspheres. The effects of raw mass ratio, curing time and pyrolysis temperature on the formation and the morphology of core-shell microspheres were studied. The morphology, chemical composition and phase transformation were characterized by SEM, EDS, TEM, FT-IR and XRD. The results show that after reaction for 4h at 200℃, SiO2 completely coated PSN forms a core-shell microsphere with rough surface when the mass ratio of SiO2 and PSN is 1:4; when pyrolysis temperature is at 800-1200℃, amorphous SiO2/SiCN core-shell ceramic microspheres are prepared; at 1400℃, the amorphous phase partially crystallizes to produce SiO2, SiC and Si3N4 phase.

Polysilazane (PSN2) was used as chemical foaming agent to prepare epoxy foam for the first time. Using the new foaming agent, epoxy foams with high strength and low density were successfully prepared. The density of epoxy foam can be tuned from 0.321 to 0.151 g cm−3 by changing the content of PSN2 from 2.50 to 7.50 wt%, with the compressive strength varied from 7.39 to 1.25 MPa. The morphology, porosity, mechanical property, thermal conductivity and adhesive property of foams with different polysilazane content were investigated. Besides, the effect of polyamine curing agent and surfactant on foams was also investigated to optimize the as-prepared epoxy foam.

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• Flexible electronics requires a flexible film with high gas barrier performance and heat resistance. • PET film with high gas barrier performance and heat resistance was developed. • This PET film has high gas barrier properties with a WVTR of 0.02 g/m2 day or less and heat resistance at 210 °C. • It is expected for this PET film to have applications in films for flexible devices. A solution of polysilazane (Perhydropolysilazane) was applied to a heat resistant PET substrate, and then irradiated with excimer light at 150 °C to form a gas barrier film. This film primarily consisted of a thin layer of SiO 2 , and had very high gas barrier properties, with a water vapor transmission rate of 0.02 g/m2·day or less (40 °C/90% RH). This gas barrier film has good transparency, film adhesion, surface flatness, and flexibility, and since it has high heat resistance and good gas barrier performance, it is expected to have applications in films for flexible devices. [ABSTRACT FROM AUTHOR]