MQ Silicone Resin Research Articles

Enhancing the damping and mechanical properties of phenyl silicone rubber by introducing phenyl MQ silicone resins as molecular fillers

Silicone rubber features excellent thermal stability, outstanding low-temperature performance, and superb processability, however, the poor damping property and low mechanical strength limit its applications. In this work, we synthesized two types of phenyl MQ resins as molecular fillers and incorporated them into phenyl silicone rubber to prepare damping composites. The effects of both the phenyl MQ resin structures and contents on the damping properties and mechanical performances were investigated. The results showed that phenyl MQ resins exhibit multiscale damping effects with temperature rising, and phenyl MQ resins are distributed in silicone rubber with a "sea-island" structure, which strengthen the mechanical property. The composite exhibit optimal performance with incorporating 30phr diphenyl MQ resins: the damping factor at 150 °C increased from 0.1 to 0.18, the temperature range for tan δ > 0.3 expanded by 115.2 %, and maintained a tensile strength of 6.3 MPa. This study paves a new path to design and prepare silicone rubber composite that balance high damping performances with better mechanical strength.

Enhanced mechanical strength and water resistance in waterborne polyurethanes through hydroxyl-functionalized MQ silicone resin modification

As an alternative to solvent-based polyurethane, waterborne polyurethane (WPU) uses water as dispersants and can significantly reduce VOC. However, dispersing polyurethanes with hydrophobic backbones in water requires hydrophilic groups, which undermine the water resistance. It remains a challenge to simultaneously improve water resistance and mechanical properties. Here we report a polyurethane with superior mechanical properties and water resistance through the introduction of an organic-inorganic hybrid material, MQ silicone resin. Hydroxyl functionalized MQ silicone resin increases chemical crosslinking and improves the microphase separation and hydrogen bonding strength of polyurethanes. When the MQ-OH content was 10.1 wt%, the tensile strength increased from 27 MPa to 37.3 MPa, and the toughness increased from 74.8 MJ/m3 to 97.4 MJ/m3. Si-O-Si backbones with low surface energy can migrate to the film surface, increasing the surface hydrophobicity. WPU films with MQ silicone resin exhibited remarkable tensile strength retention, with 84.7 % after 40 h hydrolysis in 80 °C water, while WPU retained only 24.6 %. MQ silicone resin offers a novel approach to enhance the hydrophobic properties of WPU without compromising the mechanical properties.

Toward structural regulation and characterization of MQ silicone resins

MQ silicone resins, a class of highly branched hybrid macromolecules composed of one or more M (R3SiO1/2) and Q (SiO4/2) structural units, have garnered significant attention in recent years due to their distinctive structure and properties. However, on-demand control over their chemical structures remains a formidable challenge, particularly using sodium silicate as a precursor. In this study, we systematically manipulated various polymerization factors such as temperature, reaction time, molar ratio between M and Q precursors, ethanol quantity and stirring rate to exert on-demand control over the Q-to-Q condensation and M-to-Q end-capping co-condensation in the sodium silicate method. This approach enabled us to obtain a series of MQ silicone resins with controlled molecular weight (from 19400 to 3600 Da), silanol content (from 5.65 % to 0.20 %), and M/Q ratio (from 0.56 to 0.98). The resulting materials were characterized using combined techniques to elucidate the influence of polymerization conditions on the structure and properties of MQ silicone resins. Meanwhile, the formation mechanism of MQ silicone resins was discussed, offering a guideline for controllable synthesis of MQ silicone resins. Additionally, we have developed a facile method for determining the M/Q ratio using Fourier transform infrared spectroscopy. This work not only provides insights into engineering the chemical structures but also offers valuable characterization methods for MQ silicone resins.

Synthesis and characterization of high strength and ultraviolet transmitting silicone rubber reinforced by organic solvent‐soluble trimethylsiloxysilicate polymers (MQ and MTQ copolymers)

AbstractAdditional‐type liquid silicone rubber (ALSR) has poor mechanical properties, and conventional methods to reinforce it are at the cost of decreasing transparency. Here, vinyl MQ and fluorine‐containing MTQ silicone resins were synthesized by the sol–gel method. Then, high strength and ultraviolet (UV) transmitting ALSR were prepared using MQ and MTQ silicone resins as reinforcing agents, vinyl‐terminated silicone oil, and polydimethylmethylhydrosiloxane as matrix, respectively. The results show that the enhancement effect of MTQ silicone resin on the mechanical properties of ALSR resin is better than that of MQ silicone resin due to the vinyl content of MTQ silicone resin being higher than that of MQ silicone resin. Compared with pure ALSR, the tensile strength, Young's modulus, and Shore hardness of ALSR with 7 wt% MTQ silicone resin are enhanced by 435%, 127%, and 14%, respectively. The thermal stability of ALSR is slightly increased. The modified silicone rubber also has favorable transparency. Additionally, the MTQ/ALSR composites show higher UV transmittance than MQ/ALSR systems owing to the introduction of fluorine element increasing UV transmittance. The high strength and UV transmittance silicone rubber composites were prepared by using a small addition of MTQ silicone resin.

Sensitive quantification of the surface Si–OH group in MQ silicone resins by benzoylation and GPC−UV analysis

The content of the Si–OH group markedly affects the physical and chemical properties of MQ silicone resin (MQ) and its secondary processing products. However, current methods for the determination of the Si–OH group are still unsatisfactory due to their insensitivity and inaccuracy. Herein, an accurate analytical method has been developed for the determination of the active Si–OH group in MQ based on benzoylation and GPC–UV analysis. The UV-insensitive Si–OH group in MQ was converted to a UV-sensitive benzoyl group by the benzoylation with p-methoxy benzoyl chloride, which greatly improved its detection sensitivity. The interference of water was also excluded by the introduction of GPC separation. The effect of several derivatization parameters was investigated and optimized, and complete benzoylation of the Si–OH group in MQ was achieved under the optimized experimental parameters. Good linearity was obtained in a range of 0.425–42.5 μg/g for the content of the Si–OH group in MQ, with a correlation coefficient greater than 0.999. Reasonable reproducibility was also obtained, with the intraday RSD (N = 3) of 1.78 % and the interday RSD (3 days) of 3.98 %, respectively. This method has been successfully applied for the determination of the active Si–OH group in several commercial MQs.

Flame-retardant composite phase change material with silicone resin and melamine phosphate for battery thermal safety

<p>With the prosperity of electric vehicles (EVs), the thermal management of lithium-ion battery (LIB) is crucial for ensuring the safety of drivers on EVs. Composite phase change material (CPCM) with high latent heat has a great promising prospect in battery thermal management systems (BTMS). However, the thermal management efficiency of CPCM is limited due to the leakage, low thermal conductivity and flammability. Herein, the novel multifunctional CPCM with paraffin (PA), epoxy resin (ER), expanded graphite (EG), methyl MQ silicone resin (MQ) and melamine phosphate (MP) (PEE/MQ/MP3) has been prepared, which can achieve well anti-leakage, high flame-retardant and thermal conductivity, enhancing the thermal safety for battery module. The results reveal that PEE/MQ/MP3 with MQ and MP at a ratio of 1:2 can exhibit optimum flame retardant performance. The total heat release peak, smoke production rate, carbon monoxide production and carbon dioxide production are 169 MJ/m<sup>2</sup>, 0.05 m<sup>2</sup>/s, 0.005 g/s and 0.38 g/s, respectively. The battery module with PEE/MQ/MP3 displays excellent thermal management performance, delaying thermal propagation. Even after ten cycles at a 3 C rate, the maximum temperature is controlled below 50 ��C and the maximum temperature difference is maintained with 5 ��C. Besides, the thermal propagation processes of battery modules reveal that PEE/MQ/MP3 can absorb and transfer heat in the first stage timely and quickly, efficiently suppressing the thermal hazard occurrence. Therefore, this study has proposed a multifunctional flame-retardant CPCM as an effective solution to enhance the thermal safety of battery modules, thus ensuring the safety of EV drivers.</p>

Polyether-Thiourea-Siloxane Copolymer Based on H-Bonding Interaction for Marine Antifouling.

By introducing thiourea and ether groups into MQ silicone resin polymer via free radical polymerization, a polyether-thiourea-siloxane (PTS) copolymer was synthesized. The characterization of the synthesized copolymer indicated the occurrence of H-bonding interactions and a narrow molecular weight polydispersity index. Antifouling coatings were produced by incorporating the synthesized copolymer and phenylmethylsilicone oil (PSO). The addition of a minute amount of copolymer enhanced the hydrophobicity of the coating by increasing its surface roughness. However, excessive addition of copolymer resulted in a significant deterioration of the coating surface smoothness. The copolymer improved the mechanical properties of the coating, but excessive addition decreased the crosslinking density and weakened the mechanical performance. With increasing copolymer addition, the leaching of PSO was significantly improved due to the change in the storage form of PSO in the coating caused by the copolymer. Based on the H-bonding interaction of the copolymer, the adhesion strength between the coating and the substrate was significantly improved. However, excessive addition of copolymer did not infinitely enhance the adhesion strength. The antifouling performance demonstrated that an appropriate amount of copolymer could obtain adequate PSO leaching efficiency, thereby effectively enhancing the antifouling performance of the coating. In this study, the prepared coating P12 (12 g of PTS in 100 g of PDMS) showed the most effective antifouling performance.

Preparation and Properties of α‐Cyanoacryloyloxyethoxypropyl‐functionalized MQ Silicone Resin

Abstractα‐Cyanoacryloyloxyethoxypropyl‐functionalized MQ resins were synthesized using commercially available hydrogen‐containing MQ silicone resin and 2‐(allyloxy)ethoxytrimethylsilane through a series of hydrosilylation, condensation and retro‐Diels‐Alder reactions. Under the conditions of room temperature and relative humidity of 60 %, the prepared silicone resins could be completely cured within 10 h without adding any promoters. When a small amount of N, N‐dimethyl‐p‐toluidinewas added as an accelerator, the curing time could be shortened to 3–5 s. Although grafted α‐cyanoacryloyloxyethoxypropyl groups on MQ resins reduced their thermal stabilities, the introduction of α‐cyanoacryloyloxyethoxypropyl groups destroyed the order of polysiloxane segments and eliminated the crystallization behavior of polysiloxane, which is beneficial to maintain structural stability of the functionalized polysiloxanes over a wide temperature range. The water contact angle of the cured product decreased from 102° to approximately75° when α‐cyanoacryloyloxyethoxypropyl groups were grafted to the polysiloxaneand thus changed the hydrophobicity of the polydimethylsiloxane materials to hydrophilicity. The novel α‐cyanoacryloyloxyethoxypropyl‐functionalized MQ resins not only maintain the inherent flexibility of polysiloxanes but also endow the silicone materials with the characteristics of fast cross‐linking.

Facile preparation method of phase change microcapsule with organic-inorganic silicone shell for battery thermal management

Microencapsulation is commonly adopted to improve the stability and expand the application of phase change materials. We developed a novel phase change microcapsule with MQ silicone resin (MQ), a typical organic-inorganic hybrid polysiloxane, as its shell material through a simple preparation process. Its morphology, including its core-shell microstructure and size distribution, was observed via scanning electron microscopy, transmission electron microscopy, and laser diffraction particle size analysis. The microcapsule exhibited the best thermal properties and shape stability at a core-shell ratio of 2:1, where the thermal energy storage capacity was 80.21 kJ kg−1. It was then composited with silicone rubber (SR) to form a composite. Owing to the chemical structure of MQ, the microcapsule presented enhanced mechanical properties with the SR matrix. When the composite was used for battery thermal management of a commercial prismatic LiFePO4 battery at 1C, the maximum temperature could be reduced by more than 10 °C, and the maximum temperature difference could be controlled within 5 °C.

Bio-based epoxy functionalized MQ silicone resins: from synthesis to toughened epoxy composites with good mechanical properties, thermal resistance and transparency

A series bio-based eugenol silicone resins are synthesized, and EG-1.2MQ shows its good promise as a new green multifunctional additive to well balance the toughness, mechanical properties, transparency, and other properties.

Facile Fabrication of a Mechanical, Chemical, Thermal, and Long‐Term Outdoor Durable Fluorine‐Free Superhydrophobic Coating

AbstractDespite their great self‐cleaning, anti‐dust, and anti‐icing properties superhydrophobic coatings show great promise in various practical applications in solar cells, car windows, powerlines, etc., superhydrophobic coatings encounter a large resistance in large‐scale practical applications due to their unsatisfactory long‐term mechanical, chemical, thermal, and weathering durability. This study demonstrates a cost‐effective, large‐scale applicable, mechanical, chemical, thermal, and long‐term weathering durable fluorine‐free superhydrophobic coating. This coating can be prepared with a simple spin‐coating or doctor‐blade painting or spray‐brush method, using SiO2 nanoparticles coated with methyl MQ silicone resin (Me‐MQ), and y‐methacryloxypropyltrimethoxysilane (KH‐570). This coating displays remarkable super‐hydrophobic performance with a large water contact angle of 168.8°, and a small sliding angle less than 1.0°, which survives tape peeling, sand impact, sandpaper abrasion, etching in acidic and alkaline environments, baking at high temperature up to 550 °C, and long‐term exposure to outdoor natural environment (under 16 months’ natural sunlight irradiation, UV irradiation, rain falls, high PM2.5, dust accumulation, etc.). The materials used are non‐fluorine, non‐toxic, environmentally friendly, and can be effectively applied to large glass surfaces using cost‐effective doctor‐blade painting and spray‐brush methods towards large‐scale applications. Therefore, this work can inspire and advance researches on superhydrophobic coatings towards practical applications.

Insights into the reinforcement and mechanism of silicone mold rubber co-modified with WCB and MMQ resin

The exploitation of condensation room-temperature vulcanized silicone rubber (C-RTV) with excellent mechanical properties and thermal stability is of great practical significance in the preparation of insulation materials and rubber products with high performance. In this work, novel silicone rubber was fabricated successfully by adding white carbon black (WCB) and different percentages of methyl MQ (MMQ) silicone resin to C-RTV silicone mold rubbers (C-RTV/WMMQ). The mechanical properties, dimensional thermal stabilities, and thermal decomposing temperatures of the as-prepared samples were investigated in detail. Compared to the primitive C-RTV, the tensile strength of the sample with the WCB adding an amount of 15% increased from 0.44 MPa to 3.9 MPa. When the 1% MMQ was introduced, the tensile strength further increased to 4.4 MPa, suggesting a 12.8% reinforcement rate in addition to the improvements in the dimensional thermal stabilities and decomposing temperature. Based on the experimental results, a feasible synergistic effect and compatibility mechanism was proposed that hydrogen bond formed on the interface between MMQ resin and C-RTV in addition to the rigid structure of WCB, and thus led to a dense crosslinking network structure in the polymer matrix.

Thermo-reversible phase structures of lightly cross-linked PDMS/MQ silicone polymer blends

The phase structures of lightly cross-linked poly (dimethyl siloxane) (PDMS)/MQ silicone polymer blends were analyzed using scanning probe microscopy (SPM) and pulsed 1H NMR. The MQ silicone resins comprised three-dimensional oligomers made of M units ((CH3)3SiO1/2) and Q units (SiO4/2). The SPM observations demonstrated that these blends had sea/island-type phase structures, in which hard MQ phases were dispersed in a soft matrix. The pulsed 1H NMR showed that the soft matrix was not pure PDMS but rather composed of a PDMS-rich phase incorporating dissolved MQ, whereas the dispersed phase was almost pure MQ. Magnetic relaxation spectra obtained using the pulsed 1H NMR were used to quantify the proportions of the MQ domains and the PDMS-rich matrix and to evaluate the molecular mobility of each component. The molecular motion of the PDMS-rich matrix was found to become more constrained with increases in the proportion of MQ. The effect of temperature on the magnetic relaxation spectra was assessed and the MQ domains were determined to partially dissolve in the PDMS matrix at higher temperatures and then to precipitate on cooling. The spectra obtained during heating and cooling were superimposable at intermediate temperatures, indicating that the phase structures of the blends were thermo-reversible.

Synthesis of High Molecular Weight Vinylphenyl-Con Taining MQ Silicone Resin via Hydrosilylation Reaction

To overcome the inherent limitation that the preparation of high molecular weight MQ copolymers (Mw ≥ 30,000 g/mol) via the hydrolysis and condensation of solicate salts generally results in an intractable gel, vinylphenyl-containing MQ silicone resin with a high molecular weight was designed and synthesized through the hydrosilylation reaction of vinyl-containing MQ silicone resin and linear poly(diphenylsiloxane) with two terminal Si–H bonds. The weight average molecular weight of these modified copolymers reported here is at least 30,000 dal·mol−1. These polymers have favorable thermal stability and a higher refractive index than that of the base resin due to the formation of novel regular macromolecular structures and the introduction of phenyl groups. These inorganic/organic hybrid materials could be used as a potential component for temperature-resistance electronics adhesive, heat-resistant coatings and high-performance liquid silicone rubber. Moreover, the proposed process also provides a possibility to choose higher molecular weight MQ silicones according to application requirements.

Synthesis and characterization of ureido-containing MQ silicone resin

Ureido-containing MQ silicone resin (U-MTQ) was synthesized by the hydrolysis and co-condensation reaction of ethyl silicate, ureido silane, hexamethyldisiloxane, and divinyltetramethyldisiloxane under the catalysis of hydrochloric acid. U-MTQ was characterized by FT-IR, 1H-NMR, 29Si-NMR, GPC and TGA. The influences of M/Q molar ratio and hydrochloric acid content on the yield and structure of U-MTQ were investigated. The results showed that the M/Q molar ratio of the product calculated from the 29Si-NMR spectrum was much smaller than that in the feed. As M/Q molar ratio in the feed increased, the molecular weight and its distribution index of U-MTQ decreased, and Si-OH content of U-MTQ also decreased, while the structural regularity of U-MTQ was enhanced. With HCl content increasing, the molecular weight and its distribution index of U-MTQ decreased, but the Si–OH content and structural regularity increased. Meanwhile, the yield first increased and then decreased, and reached the highest value of 71.9% when HCl content was 2.10%. Compared with MQ, the onset weight loss temperature of U-MTQ decreased from 237 °C to 158 °C, and the residue at 900 °C increased from 3.5% to 29.5%.

A Simple Preparation Route for Bio-Phenol MQ Silicone Resin via the Hydrosilylation Method and its Autonomic Antibacterial Property.

MQ silicone resins represent a broad range of hydrolytic condensation products of monofunctional silane (M units) and tetrafunctional silane (Q units). In this work, a Bio-Phenol MQ silicone resin (BPMQ) was designed and synthesized by the hydrosilylation of hydrogen containing MQ silicone resin and eugenol in the presence of chloroplatinic acid. The structure, thermal property, and antibacterial property against Escherichia coli of the modified MQ silicone resin were investigated. The results showed that BPMQ has been prepared successfully, and the thermal stability of this modified polymer improved significantly because of the introduction of phenyl in eugenol. The temperature at the maximum degradation rate increased from 250 °C to 422.5 °C, and the residual yields mass left at 600 °C were increased from 2.0% to 28.3%. In addition, its antibacterial property against Escherichia coli was also enhanced markedly without adding any other antimicrobial agents. This improved performance is ascribed to special functional groups in the structure of eugenol. The BPMQ polymer is expected to be applied to pressure-sensitive adhesives and silicone rubber products for the biomedical field due to its reinforcing effect and antioxidant quality.

Synthesis and Characterization of Room Temperature Vulcanized Silicone Rubber Using Methoxyl-Capped MQ Silicone Resin as Self-Reinforced Cross-Linker.

Methoxyl-capped MQ silicone resin (MMQ) was first synthesized by the hydrosilylation of vinyl-containing MQ silicone resin and trimethoxysilane and then used in condensed room-temperature vulcanized (RTV) silicone rubber as a self-reinforced cross-linker. Results show that modified silicone rubber exhibits good light transmission. Compared with unmodified silicone rubber, the hardness, tensile strength and elongation of MMQ at the break are increased by 26.4 A, 2.68 MPa and 65.1%, respectively. In addition, the characteristic temperature of 10% mass loss is delayed from 353.5 °C to 477.1 °C, the temperature at maximum degradation rate is also delayed from 408.9 °C to 528.4 °C and the residual mass left at 800 °C is increased from 1.2% to 27.7%. These improved properties are assigned to the synergistic effect of the rigid structure of MMQ, the formation of a dense cross-linking structure in polymers and the uniform distribution of MMQ cross-linking agent in RTV silicone rubber.

Investigation of ureido‐attached vinyl MQ silicone resin on tracking and erosion resistance of addition‐cure liquid silicone rubber

ABSTRACTWith the growing incidence of extreme climate and serious pollution, the capability to resist high‐voltage arc discharge has been considered as one of crucial performances for silicone rubber in the field of electrical power. Herein, to enhance the tracking and erosion resistance of addition‐cure liquid silicone rubber (ALSR), a kind of ureido‐attached vinyl MQ silicone resin [hydrolytic condensation products of monofunctional silane (M) and tetrafunctional silane (Q)] (U‐VMQ) was synthesized. The chemical structure of U‐VMQ was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance, and the effects of U‐VMQ on the mechanical properties, thermal stability, and tracking and erosion resistance of ALSR were investigated. The results showed that U‐VMQ was beneficial for the improvement of mechanical properties and thermal stability of ALSR. With 2 phr of U‐VMQ containing 2.5 wt % of vinyl content, the ALSR successfully passed the inclined plane tracking at 4.5 kV, and the electrical erosion rate was only 0.13%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47360.

Plasma resistance of addition-cure liquid silicone rubber with Ureido-attached MQ silicone resin

Ureido-attached MQ silicone resin (U-MQ) was synthesized and added into addition-cure liquid silicone rubber (ALSR) for the improvement of the plasma resistance. The morphology and chemical structure of the surface of ALSR/U-MQ after plasma treatment were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), and the water contact angles (WCAs) of the surface at different recovery time were also measured. The results indicated that the surface of ALSR/U-MQ was slightly destroyed after plasma treatment, exhibiting excellent plasma resistance. Furthermore, the increasing rate of WCAs of ALSR with U-MQ kept faster than that of ALSR without U-MQ at different recovery time after plasma treatment, also demonstrating the lower destruction degree of ALSR/U-MQ. It was possible that inorganic ceramic layer was gradually formed on the surface of ALSR/U-MQ under plasma treatment, which was beneficial to protect the inner matrix from serious destruction.

Reduced Graphene Oxide Embedded with MQ Silicone Resin Nano-Aggregates for Silicone Rubber Composites with Enhanced Thermal Conductivity and Mechanical Performance.

With developments of the electronics industry, more components are being included in electronic devices, which has led to challenges in thermal management. Using reduced graphene oxide embedded with MQ silicone resin (RGO/MQ) nano-aggregates as the composite filler and silicone rubber (SR) as the matrix, a simple approach is designed to prepare RGO/MQ/SR composites. Reduced graphene oxide (RGO) was first used as a substrate for the growth of MQ silicone resin by hybridization, forming sandwich-like micro structured RGO/MQ nano-aggregates successfully. Then, RGO/MQ was integrated into α,ω-dihydroxylpolydimethylsiloxane based on the in situ solvent-free blending method, followed by condensation and vulcanization, fabricating the final RGO/MQ/SR composites. The effective strategy could enhance the adaptability between graphene and silicone matrix under external stimuli at room temperature by embedding nanoscale MQ into the interface of graphene/silicone as the buffer layer. Obvious improvements were found in both thermal conductivity and mechanical properties due to excellent dispersion and interfacial compatibility of RGO/MQ in the host materials. These attractive results suggest that this RGO/MQ/SR composite has potential as a thermal interface material for heat dissipation applications.