Robust superhydrophobic silicone/epoxy functional coating with excellent chemical stability and self-cleaning ability

Superhydrophobic surfaces have attracted broad attention because of their unique water repellency but are restricted by poor wear resistance, weak adhesion to the substrate, and complex fabrication processes. Herein, a double-layer coating strategy consisting of the amino fluorine-silicone resin/epoxy resin (AFSR/EP) system is created. The system features a high hardness and transparent hydrophobic interface adhesive layer through the amine-epoxy "click" chemical reaction. The environmentally friendly resin system and low-cost nano-silica particles (n-SiO2) are composited and sprayed onto the substrate surface to form a superhydrophobic layer with outstanding robustness and excellent environmental stability. The prepared AFSR/EP@n-SiO2 composite coatings have a water contact angle of 161.1° and a sliding angle of 3.4°, demonstrating high superhydrophobic properties. Benefitting from the complementary advantages of silicone/epoxy resin, the prepared composite coatings maintain remarkable water repellency after various harsh environmental tests, including cyclic mechanical abrasion and tape-stripping, acid-base (pH 1 and pH 14) treatment, 10 wt% NaCl (pH 7) salt solution immersion, temperature treatment, knife scratching, and long-term ultraviolet radiation treatment, showing reinforced mechanical robustness and durable anti-corrosion stability. Notably, surface hardness of 5H and optical transparency over 80% can be achieved. The simple method offers a novel approach for the large-scale preparation of multifunctional superhydrophobic coatings.

A Rigid-Flexible and Multi-Siloxane Bridge Strategy for Toughening Epoxy Resin with Promising Flame Retardancy, Mechanical, and Dielectric Properties

Developing highly efficient and multifunctional epoxy resins (EPs) that overcome the shortcomings of flammability and brittleness is crucial for pursuing sustainable and safe application but remains a huge challenge. In this paper, a novel biomass-containing intumescent flame retardant containing a rigid-flexible and multi-siloxane bridge structure (DPB) was synthesized using siloxane; 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO); and biomass vanillin. DPB could facilitate the formation of a carbon residual with an intumescent structure, which effectively blocked the propagation of heat and oxygen. As a result, the peak heat release rate (pHRR) and total heat release (THR) of DPB/EP-7.5 decreased by 38.8% and 45.0%, respectively. In terms of mechanical properties, the tensile and flexural elongations at break of DPB/EP-7.5 increased by 77.2% and 105.3%, respectively. Impressively, DPB/EP-7.5 had excellent dielectric properties, with a dielectric constant of 2.5-2.9. This was due to the Si-O bonds (multi-siloxane bridges) contained in DPB/EP, which can quench the polarization behavior of the hydroxyl group. This paper provides a facile strategy for the preparation of multifunctional EP, which will pave the way for the promotion and application of EP in the high-end field.

Curing kinetics, thermal and erosive wear characteristics of bismaleimide blends modified by polyaryletherketone

The work aimed to study the effect of thermoplastic polyaryletherketone (PAEK) on the curing kinetics, thermal stability and erosive wear performances of bismaleimide (BMI) resin blends. Toughened bismaleimide blends were fabricated using the allyl compound modified bismaleimide resin prepolymer as matrix and PAEK as a toughening agent by blending method. The modified PAEK/BMI blends were characterized and analyzed using the fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), the swirling water jet erosive wear apparatus, scanning electron microscope (SEM) and three-dimensional surface profilometer. No obvious glass transition was observed for PAEK modified BMI blends in the temperature range of 50–350°C. In addition, the char yields ( Yc) and the heat-resistance index ( THRI) of the PAEK/BMI blends were affected by PAEK addition. The kinetic parameters, such as the activation energy and the pre-exponential factor of the PAEK/BMI blends were also higher than that of unmodified BMI blends, indicating that the incorporation of PAEK could promote the curing reaction of the epoxy resin without changing the curing mechanism. The erosive wear rate increased with the addition of PAEK especially when the mass fraction of PAEK was 10 parts per hundred of resins ( phr.). These results suggested that the thermal stability of the PAEK/BMI blends was significantly enhanced while the erosive wear resistance decreased by introducing the PAEK.

Cyanate ester resins with superior dielectric, mechanical, and flame retardant properties by introducing fluorinated hyperbranched polyaryletherketone

Cyanate ester resins are broadly applied in electronic packaging, printed circuit boards, radome, and communication satellites. Herein, a novel fluorinated hyperbranched polyaryletherketone (HBPAEK) with epoxy terminal group was synthesized by...

Improved thermal and mechanical properties of bismaleimide nanocomposites via incorporation of a new allylated siloxane graphene oxide

A thermosetting resin system based on bismaleimide (BMI) has been developed via copolymerization with 4,4′-diaminodiphenylsulfone in the presence of a newly synthesized graphene oxide, modified using allylated siloxane (AS-GO). The curing behavior of the AS-GO-containing resin system was evaluated using curing kinetics. The dispersibility of AS-GO in the resin was observed through polarizing optical microscopy (POM), which indicates that AS-GO has good dispersibility in the resin due to GO modified with allylated siloxane which has a good phase compatibility with BMI. The effect of AS-GO on the thermomechanical and mechanical properties of the cured modified resin was also studied. Results of thermogravimetric analysis indicated that the cured sample systems display a high char yield at lower concentrations of AS-GO (≤0.5 wt%) with an improved thermal stability. Using dynamic mechanical analysis, a marked increase in glass transition temperature (T_g) with increasing AS-GO content was observed. Mechanical property analyses revealed a possible effect of AS-GO as a toughener, and the results showed that an addition of 0.3% AS-GO maximized the toughness of the modified resin systems, which was confirmed by analysis of fracture surfaces.

A thermosetting resin system based on bismaleimide has been developed via copolymerization of a new allylated siloxane graphene oxide.

Fabrication of new conductive surface-metallized UHMWPE fabric with improved thermal resistance

A new UHMWPE-based conductive fabric was successfully prepared by radiation-induced graft polymerization and subsequent post-modification, followed by electroless deposition. The chemical structure and composition of modified UHMWPE fabrics were investigated in detail by ATR-FTIR, ²⁹Si NMR, and XPS to confirm grafting and post-modification. After electroless deposition, the morphology, thermal stability, and crystal structure of original and modified fabrics were characterized by SEM, TG, DSC and XRD. Cu-deposited UHMWPE fabric exhibited much better thermal resistance than that of UHMWPE and Cu@UHMWPE-g-PAAc. In order to improve the oxidation resistance of copper-deposited fabric, nickel was processed on copper-coated UHMWPE fabric to protect the copper layer. An electromagnetic shielding effect test showed the nickel-copper coated UHMWPE fabric could shield 94.5% of the electromagnetic wave in the frequency range of 8-12 GHz. This work provides an approach for addressing the issue of poor thermal resistance of metal-coated polymeric materials due to the inherent low melting point of the organic support.

Bismaleimide bridged silsesquioxane aerogels with excellent heat resistance: effect of sol-gel solvent polarity

Due to the poor heat-resistance and intrinsic weakness of the bridging moieties in aerogel matrixes, it remains greatly challenging to fabricate highly thermostable and toughened silsesquioxane aerogels. By utilizing bismaleimide as the bridging part and optimizing the solvent polarity, lightweight (ρ < 0.09 g cm-3), compressible (80% strain) and superhydrophobic (CA ≈ 150°) bismaleimide bridged silsesquioxane aerogels (BMIT-BSAs) are constructed. The microstructure and compressive modulus of BMIT-BSAs can be tuned by the sol-gel solvents with different polarities. Moreover, stable low-temperature wettability at -196 °C and a significantly increased initial deposition temperature of 336 °C for both N2 and O2 atmospheres were measured, demonstrating the wide temperature tolerance of BMIT-BSAs.

Novel allyl and propenyl monomers for modification of the bismaleimide resins, with excellent dielectric properties and high glass transition temperatures

Two new monomers were prepared by the reaction of 2-allylphenol and 4,4′-biphenyldicarbonyl chloride under different reaction conditions. The monomers were characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The curing processes of N, N-4,4′-bismaleimidodiphenylmethyene with 4,4′-bis(2-allylphenyl) biphenyldicarbonylate (BABC) and 4,4′-bis(2-propenylphenyl benzoate) ether (BPBE) were studied by rheological analysis and differential scanning calorimetry. Melting points of two monomers, BABC and BPBE, are 64°C and 121°C, respectively. The ABMI [4,4′-bis(2-allylphenyl)biphenyl bismaleimide] and PBMI [4,4′-bis(2-propenylphenyl)biphenyl bismaleimide] resins showed exothermic peaks at 233°C and 204°C, respectively. The measured melting points are significantly lower than that of the traditional bismaleimide resin which is modified by allyl bisphenol A. Dynamic mechanical analysis of the materials showed glass transition temperatures of ABMI and PBMI to be in the range of 213–258°C and 302–339°C, respectively. Thermogravimetric analysis of the cured resins showed 5% weight loss for ABMI and PMBI at 437°C and 428°C, along with char residues of 35.6–39.5%, respectively, at 800°C under nitrogen atmosphere. Furthermore, dielectric constants of propenyl-modified resins were lower (2.46–3.10) with dissipation factors of 0.0034–0.0036, compared with those of allyl bisphenol A resins.

Thermal and oxidative behavior of a tetraphenylsilane-containing phthalonitrile polymer

Phthalonitrile polymers have potential for high-temperature applications in polymer matrix composites as electronic encapsulation compounds. To investigate the effect of inclusion of an organosilicon moiety, a tetraphenylsilane-containing phthalonitrile monomer was synthesized in high yields. The monomer possessed a high melting point of 222–223°C, while no hydrolytic sensitivity was observed. Cured polymers exhibited glass transitions in the range of 290–325°C and coefficients of thermal expansion of 73–77 µm/(m °C). In thermogravimetric analysis (TGA), 5 wt% loss was observed at 482–497°C and 519–526°C, under air and nitrogen, respectively. Infrared (IR)-TGA of evolved gases revealed multiple degradations in both nitrogen and air. The material possessed good thermo-oxidative stability (TOS) when aged in air at 250°C. After aging for 5000 h, oxidative degradation was characterized using Fourier transform IR microscopy, energy dispersive spectroscopy, optical microscopy, and Knoop hardness testing. Four zones were identified in aged samples. The cleavage of Si-phenyl bonds and the formation of Si–O phases and carbonyl groups were observed.

Simultaneous reinforcement and toughness improvement of an epoxy–phenolic network with a hyperbranched polysiloxane modifier

An epoxy–phenolic network is modified with hyperbranched polysiloxane (HBPSi). The addition of HBPSi-2, which has medium molecular weight, can significantly decrease the viscosity of the uncured epoxy–phenolic system and increase the crosslinking density and homogeneity of the cured crosslinking network. With 10% HBPSi-2, the mechanical properties of the samples are improved comprehensively: tensile modulus and maximum strength increase by 11.4% and 36.2%, respectively, while elongation at break and impact strength increase by 153.8% and 186.7%, respectively. The comprehensive improvements in the mechanical properties are attributed to combined effects of crosslinking density, network rigidity, cohesive density and the matrix-modifier compatibility. What is more, HBPSi-2 also significantly increases the char yield of the material and decreases the thermal weight loss rate, indicating an improved thermal stability. All these results may provide a new strategy for toughness and strength improvement of the epoxy–phenolic network.

An epoxy–phenolic network is modified with hyperbranched polysiloxane (HBPSi).

Preparation and thermal stability of heat-resistant phenolic resin system constructed by multiple heat-resistant compositions containing boron and silicon

This work reports a boron- and silicon-containing phenolic-formaldehyde (PF) resin exhibiting an extremely high thermal decomposition temperature and char yield and formed by copolymerizing phenol, formaldehyde, boric acid (BA), and phenyltriethoxysilane (PTES). The structure of BA and PTES-modified PF (BSPF) resin was characterized by Fourier transform infrared spectroscopy. Thermal stability of the investigated composites was estimated by means of thermogravimetric analysis (TGA). The results of TGA indicated that the modified resin exhibited excellent thermal stability. Specifically, the thermoset had a char yield of 77.0% when the boron and silicon contents were only 1.27 wt% and 1.7 wt%, respectively. Compared with the unmodified resin (PF), the temperature at the maximum decomposing rate of the BSPF increased by 84°C and its charring yield was enhanced by 15.0%. The cured products of PF and BSPF were further investigated by X-ray diffraction and Raman spectroscopy, respectively. The incorporation of boron and silicon into the carbon lattice results in a decrease of interlayer spacing, and Raman ID/ IG values for PF and BSPF (2.63 and 1.32) show that the rearrangement of crystalline structure leads to an increase in graphite structure and a decrease in disordered structure upon the modification processes.

Thermally resistant unsaturated polyester resin with low dielectric loss based on special benzyl alcohol terminated hyperbranched polysiloxane for producing high efficiency motors using vacuum pressure impregnation technique

New hyperbranched polysiloxane/unsaturated polyester resins for fabricating high efficient motors through vacuum pressure impregnation technique were developed.

Fabrication and origin of flame retarding glass fiber/bismaleimide resin composites with high thermal stability, good mechanical properties, and a low dielectric constant and loss for high frequency copper clad laminates

High performance glass fiber reinforced resin composites were fabricated by designing structures of fiber and resin with unique hyperbranched polysiloxane.

Unanticipated bright blue fluorescence produced from novel hyperbranched polysiloxanes carrying unconjugated carbon–carbon double bonds and hydroxyl groups

Bright blue fluorescence-emitting hyperbranched polysiloxane simultaneously carrying unconjugated carbon–carbon double bonds and hydroxyl groups is reported for the first time.

Hydrosoluble aliphatic tertiary amine-containing hyperbranched polysiloxanes with bright blue photoluminescence

Two hydrosoluble aliphatic tertiary amine-containing hyperbranched polysiloxanes are explored. The resulting conventional chromophore-free polymers, without any treatment, such as acidification or oxidation, can emit bright blue fluorescence.

Fabrication of modified bismaleimide resins by hyperbranched phenyl polysiloxane and improvement of their thermal conductivities

Synthetic terminal amine group hyperbranched phenyl polysiloxane (NH₂-HBPSi) is introduced into a bismaleimide/diallylbisphenol A (BMI/DABA) prepolymer to fabricate NH₂-HBPSi/BMI/DABA resins.

Hyper-branched polymer grafting graphene oxide as an effective flame retardant and smoke suppressant for polystyrene

A well-defined functionalized graphene oxide (FGO) grafted by hyper-branched flame retardant based on N-aminoethyl piperazine and phosphonate derivative was synthesized to reduce flammability and toxicity of polystyrene (PS). The chemical structure, morphological and thermal properties were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis, respectively. Micro combustion calorimeter and steady state tube furnace were employed to evaluate the heat and non-heat fire hazards of PS nanocomposites. The incorporation of FGO into PS matrix effectively improved the flame retardancy and restrained the toxicity of the volatiles escaped, which is attributed to that the homogeneous dispersion of FGO in the PS matrix enhanced barrier effect that reduced peak heat release rate, total heat release and toxic gas release during combustion. Furthermore, PS-FGO nanocompsites obviously decreased the amount of flammable and toxic volatiles evolved, such as the aromatic compounds, carbonyl compounds, carbon monoxide, indicating suppressed fire hazards of the PS composites.

The effect of functionalized benzoxazine with allyl groups on the dielectric, mechanical and thermal properties of BMI/BADCy composites

The incorporation of functionalized benzoxazine with allyl groups into BMI/BADCy composites can induce an interpenetrating network (IPN) structure and the fracture surface will change from a riverlike shape to a ductile sunken shape.

Novel tough and thermally stable cyanate ester resins with high flame retardancy, low dielectric loss and constant based on a phenolphthalein type polyarylether sulfone

Tough cyanate ester resins with good compatibility, low dielectric loss, high flame retardancy and thermal stability were developed.

Interfacial carbonation for efficient flame retardance of glass fiber-reinforced polyamide 6

The interfacial carbonation mode is introduced to solve the high flammability of GF-reinforced polymer composites through interfacial char produced.

A novel epoxy-functionalized hyperbranched polysiloxane (HPSi) endowing methyl phenyl silicone resin (Si603)/epoxy systems with enhanced compatibility and fire retardancy performance

A novel hyperbranched polysiloxane (HPSi) with a great amount of epoxy groups was synthesized as a compatibilizer of epoxy resin (EP)/methyl phenyl silicone resin (Si603) blends.