Arylacetylene Resin Research Articles

Preparation and Properties of High‐Temperature‐Resistant and Low‐Dielectric Constant Silicon‐Containing Arylacetylene Resin/SiO2 Syntactic Foams

A silicon‐containing arylacetylene resin (PSA)/SiO2 syntactic foam was prepared through a chemical foaming approach, with PSA serving as the matrix, quartz sand (QS) and nanosilica (nSiO2) acting as fillers, and their structures and properties were characterized. The results show that the incorporation of appropriate amounts of QS and nSiO2 can reduce the cell size and apparent density of the syntactic foam, and improve its heat resistance, dielectric properties and wave transmission properties. The addition of QS can increase the compressive strength of the syntactic foam, while the addition of nSiO2 decreases the compressive strength. The apparent densities of the PSA/9QS and PSA/9nSiO2 syntactic foams with 9% filler addition are 0.242 g cm−3 and 0.157 g cm−3, respectively, and the temperatures at 5% weight loss (Td5) under a nitrogen atmosphere were 692 °C and 658 °C, respectively. The dielectric constants were 1.59 and 1.25, respectively. The wave transmittance within the frequency range of 8.2–12.4 GHz was 98.5% and 96.8%, respectively. PSA/SiO2 syntactic foam can be used as a lightweight and high‐temperature‐resistant wave‐transmission material in aerospace and other fields.

Preparation and Characterization of Lightweight Carbon Foam Derived From Silicon‐Containing Arylacetylene Resin With Antioxidant Properties and Excellent Electromagnetic Interference Shielding Performance

ABSTRACTIn this study, carbon foam derived from silicon‐containing arylacetylene resin (CFPSA) was prepared by using silicon‐containing arylacetylene (PSA) resin as the carbon precursor and polyurethane (PU) foam as the organic sacrificial template. CFPSAs with diverse apparent densities were prepared through the simple impregnation of PU foam with PSA resin solutions of varying concentrations. Their structures, such as the pore morphology; chemical composition; thermal stability; compression properties, and electromagnetic interference (EMI) shielding effectiveness (SE), were characterized. The results indicate that with an increase in the PSA resin concentration, the skeleton of CFPSA becomes thicker, the pore size slightly increases, the apparent density increases, the compressive strength increases, and the EMI SE slightly reduces. CFPSA‐10's apparent density is 0.032 g/cm3, its 5% thermal weight loss temperature (Td5) in an air atmosphere is 642°C, its thermal conductivity is 38.1 mW/m K, its specific compression strength is 2.45 MPa/g cm3, and its specific EMI SE divided by thickness (SSE/t) is 2367 dB cm2/g. CFPSA exhibits lightweight and antioxidant properties, as well as excellent electromagnetic interference shielding performance, presenting great potential for application in aerospace and other fields.

Preparation and Characterization of Cyano-Silicon-Containing Arylacetylene Resins and Their Composites: Dual Enhancement Strategy Involving Physical Interfacial Interactions and Chemical Crosslinking

Preparation and Characterization of Cyano-Silicon-Containing Arylacetylene Resins and Their Composites: Dual Enhancement Strategy Involving Physical Interfacial Interactions and Chemical Crosslinking

Synthesis and properties of silicon-containing poly(diethynylbenzen-co-phenoxyphenoxybenzenediacetylene)s

Good mechanical properties, heat resistance and processability are the basic requirements of matrix resins for high performance heat resistant composites. The existing two types of silicon-containing arylacetylene resins, poly (silylene arylacetylene) (PSA) and poly (silane arylether arylacetylene) (PSEA), cannot balance these three requirements well. To achieve this goal, an attempt was made to synthesize a copolymerized resin containing both diethynylbenzene and diynyl arylether structures in the main chain, silicon-containing poly (diethynylbenzene-co-phenoxyphenoxybenzenediacetylene). By controlling the amount of 1,3-diethynylbenzene ( m-DEB) and 1,3-bis(4′-ethynylphenoxy)benzene ( pmp-BEPB), several random copolymerized resins with various ratios of m-DEB to pmp-BEPB were synthesized by the Grignard reactions. The results show that the introduction of m-DEB could effectively reduce the viscosity of the resin, and thermal stability of the cured resin is improved, but the mechanical strength of the cured resin is slightly reduced. The copolymerized resin has good overall performance when the amount of m-DEB and pmp-BEPB is equal. The processing window of the resin is 56∼169°C, the flexural strength and modulus of the cured resin are 32.9 MPa and 2.7 GPa, respectively, and the temperatures of 5% weight loss (Td5) of the cured resin is 589°C in nitrogen.

Thermal curing mechanisms and cross-linking network structure of a novel silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene unit

Silicon-containing arylacetylene resin and its composites have attracted great interest as emerging heat-resistant materials, but their curing mechanisms and products are still elusive. In this work, the influences of the terminal and inner acetylenes on the curing mechanisms of silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene were first identified by density functional theory. Two reaction pathways were proposed and their products include polyenes, anthracene dimers, and benzene trimers. To gain a distinct observation of the cross-linking process, molecular dynamics simulations were used to construct a cross-linking polymerization model. The effects of the temperature on the cured structure were investigated by analyzing the characteristics of the cross-linked network. As expected, higher curing temperature will make the larger proportion of polyene chain and aromatic ring in the terminal alkyne−terminal alkyne route, meanwhile, for the inner alkyne−inner alkyne route, the short chains and a small amount of aromatic rings are major productions. Overall, our cross-linking method may provide an unique guidance for studying the cured structure of other thermosetting resins.

Evaluating two stages of silicone-containing arylene resin oxidation via experiment and molecular simulation

Silicon-containing aryl acetylene resin (PSA) is a new type of high-temperature resistant resin with excellent oxidation resistance, whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still remains unclear. Herein, the oxidation behavior and mechanisms of PSA resin are systematically investigated combining kinetic analysis and ReaxFF molecular dynamics (MD) simulations. Thermogravimetric analysis indicates that the oxidation process of PSA resin undergoes two main steps: oxidative weight gain and oxidative degradation. The Distributed Activation Energy Model (DAEM) is employed for describing oxidation processes and the best-fit one is obtained using genetic algorithms and differential evolution. DAEM model demonstrates that the oxidative weight gain stage is dominated by two virtual reactants and the oxidative degradation stage consists of three virtual reactants. Correspondingly, the observation of MD reaction pathways indicates that oxygen oxidation of unsaturated structures occurs in the initial stage, which results in the formation of PSA resin oxides. Furthermore, cracked pieces react with O2 to generate CO and other chemicals in the second step. The resin matrix's great antioxidation resilience is illustrated by the formation of SiO2. The analysis based on MD simulations exhibits an efficient computational proof with the experiments and DAEM methods. Based on the results, a two-stage reaction mechanism is proposed, which provides important theoretical support for the subsequent study of the oxidation behavior of silica-based resins.

Exploring the impact of backbone architecture on the thermal decomposition of silicon-containing arylacetylene resins

Silicon-containing arylacetylene (PSA) resins are promising heat-resistant polymers. However, little is known about their decomposition mechanisms. A molecular dynamics (MD) study based on reactive force field (ReaxFF) was employed to investigate the thermal decomposition mechanism of two representative PSA resins containing benzene or naphthalene in the backbone. The effect of heating rate, temperature, and crosslinking degree on decomposition behavior was examined, and the temperatures of three decomposition stages were disclosed. The predicted 5% decomposition temperatures (Td5) and decomposition products are consistent with experimental findings. The ReaxFF MD simulation reveals that the Td5 is dominated by the secondary decomposition and final decomposition, in which the high molecular weight and the stable CC bond of naphthyl play a dominant role in determining high-temperature resistance of the naphthalene-containing PSA resin. We also disclose the decomposition pathways of PSA-type resin. The results gained from the present work can be a helpful guideline for designing resins with excellent heat resistance.

Understanding curing dynamics of arylacetylene and phthalonitrile thermoset blends

AbstractTetrakis(phenylethynyl)benzene (TPEB), a high char yield arylacetylene resin, was blended with a resorcinol‐based PEEK™‐like oligomeric phthalonitrile resin (Res). We observed the influence of each polymer precursor on the structural changes and material dynamics of different mixtures of these resins during thermal curing to produce thermosets with high char retention. We provide insight to help understand fundamental processes that control and tune this complex thermally driven curing mechanism, which, to date, has not been well understood. We show that an equivalent blend of Res and TPEB mitigates the exothermic curing process and exhibits a low viscosity, which may facilitate processing of these thermosetting blends for composite manufacturing. To obtain a more comprehensive overview of the different dynamics of these polymers during curing, we correlated thermodynamic changes with rheology, materials characterization, and molecular dynamics derived from neutron scattering. Our efforts shed more light on the thermally driven chemical changes, physical transformation, and gelation dynamics that drive or accompany softening and curing of these two distinct crosslinking resin groups.

Design of silicon-containing arylacetylene resins aided by machine learning enhanced materials genome approach

Silicon-containing acetylene resins have a broad application prospect as a type of organic–inorganic hybrid high-temperature resistant resins. However, its processability still needs further improvement to meet processing requirements for low viscosity. We proposed a materials genome approach to design and screen silicon-containing acetylene resins with excellent processing properties and heat resistance. To high-throughput screen the promising resin, we established machine learning models for predicting the properties of processing and heat resistance. Ten latent resins were screened, and one easy-to-synthesize resin was prepared by the Grignard reagent method to verify the materials genome approach. The results showed that the processing properties of the screened resin are improved evidently, with excellent heat resistance maintained. This work generates a fresh way for cost-effective data-driven designs of silicon-containing acetylene resins.

Assessing pyrolysis behavior of silicon-containing arylacetylene resin via experiments and ReaxFF MD simulations

Silicon-containing arylacetylene resin (PSA), a thermosetting organic-inorganic hybrid resin of high heat-resistance performs well in ablation process, whereas its pyrolysis behavior under high temperature has not been fully interpreted. Herein, the PSA pyrolysis process was in-depth investigated by experiments and ReaxFF molecular dynamics simulation (ReaxFF-MD). TG results show that the temperature of 5% weight loss (Td5) is above 600 ℃, and the residue at 900 ℃ surpass 85%, demonstrating PSA has excellent heat resistance and thermal stability. The on-line FTIR and out-line gas quantify analysis reveals that H2 and CH4 are dominant gaseous products, which are also unveiled by ReaxFF-MD simulation. Molecular reaction tracking indicates PSA pyrolysis is initiated by the cleavage of skeleton in benzene ring, the cleavage of C-C bond and C-Si bond in main chain at elevated temperature. Hydrogen abstraction reactions are primary formation pathways of CH4 and H2, together with conquering high energy barriers. The activation energy of PSA pyrolysis in experiments is 155 kJ/mol, agreeing well with that from ReaxFF MD simulations (144 kJ/mol), which further confirms the thermochemical stability of cured PSA that rich in highly crosslinked aromatic structure. Besides, the influence of silicon side-groups on PSA pyrolysis is screened by MD and results indicate that gases evolution depended largely on side-groups types and decreasing side phenyl groups in PSA is benefit for improving its thermal stability. This work deepens the understanding of PSA pyrolysis mechanism and provides theoretical guidance for improving its heat resistance.

Study on vinyl crosslinking and related properties of silicon-containing arylacetylene resin synthesised by zinc powder catalysis

A matrix resin poly(silicon-containing arylacetylene vinyl)s (PSAV) containing vinyl at both branch and terminal chains underwent synthesis via the zinc powder catalytic method using m-diacetylene benzene and dichloromethylvinylsilane as raw materials. Vinyl in the PSAV resin was crosslinked by the free radical initiator dibenzoyl peroxide to obtain a crosslinked network structure resin (PSAV-L). This approach sought to improve the thermal properties and other related properties of the matrix resin. A series of tests, such as rotated rheometer, FTIR, DSC, TGA, Py-GC-MS and universal testing machine, characterised processing property, curing behaviour, thermal properties and mechanical properties. The rheological curve shows that PSAV-L resin has a wide processing window (40–134.5°C), endowing the resin with excellent processing performance. Thermal curing behaviour indicates that PSAV-L resin can start curing at a lower temperature, namely, 32°C earlier than PSAV resin. TGA analysis shows that the degradation temperature at 5% weight loss (Td5) of PSAV-L resin stands at 579.4°C, 45.4°C higher than that of PSAV resin due to the fact that the crosslinking of vinyl gives PSAV-L resin a network structure. The flexural strength, flexural modulus and ILSS of the quartz fibre cloth reinforced PSAV-L resin composite (QF/PSAV-L) are 184.68 MPa, 15.50 GPa and 12.40 MPa. The PSAV-L resin exhibits the comprehensive properties of good processing performance, low curing temperature, excellent thermal performance and high mechanical properties.

A Novel One‐Step Synthesis of Silicon‐Containing Arylacetylene Resin Catalyzed by Et2Zn with Excellent Processability and Thermal Properties

AbstractA novel one‐step synthesis of silicon‐containing arylacetylene resin (PSA) catalyzed by Et2Zn was reported. PSA‐Et2Zn was prepared by the reaction between diethynylbenzene and dichlorodimethylsilane in the presence of diethylzinc. The structure of PSA‐Et2Zn was determined and the reaction mechanism was proposed. In addition, the processability, thermal curing behavior, and thermal properties were studied. When compared with the zinc powder catalysis method, the Et2Zn catalysis method demonstrates a greater effectiveness in avoiding the formation of olefinic products at the ends of the molecular chain, which can improve thermal capabilities. The results show that PSA‐Et2Zn possesses excellent processability and thermal properties. PSA‐Et2Zn has a wide processing window of 35∼182 °C and the thermal crosslinking reactions of PSA‐Et2Zn resin are mild. The cured PSA‐Et2Zn shows high thermal stability with a residue yield up to 87.9 % at 800 °C. Furthermore, the temperature at 5 % weight loss in nitrogen and air atmospheres is 584 °C and 539 °C, respectively.

Investigation of Poly(dimethylsilylene ethynylenealkylphenylenmethylenealkylphenyleneethynylene)

ABSTRACT A new kind of silicon-containing arylacetylene resins with the structure unit of ethynylenealkylphenylenemethylenealkylphenyleneethynylene in the main chains were synthesized. Their structures were characterized by 1H-NMR, FT-IR, Gel Permeation Chromatography (GPC), and X-Ray Diffraction (XRD). Properties of the resins such as solubility, softening point, viscosity, and processing window were determined. The mechanical properties and thermal stability of the cured resins and composites were tested. The results show that poly(dimethylsilylene ethynylenemethylphenylenemethylenemethylphenyleneethynylene) (PSMA-M) has good comprehensive performance. The flexural strength of the resin casting and its carbon fiber reinforced composite reaches 42.1 MPa and 381.9 MPa, respectively. The temperature (Td5) at 5% weight loss is 493°C under nitrogen.

Effect of side groups on the properties of silicon‐containing arylacetylene resins

AbstractFour silicon‐containing arylacetylene resins were synthesized by polycondensation of Grignard reagent of m‐diethynylbenzene with methylethyldichlorosilane, dimethyldichlorosilane, methylphenyldichlorosilane, and diphenyldichlorosilane, respectively. The structures of the resins were verified by nuclear magnetic resonance spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The solubility, crystallinity, and rheological character of the resins were characterized. The curing behavior was traced by differential scanning calorimetry (DSC) and FTIR analyses. The effect of the side groups on the silicon atom on the properties was investigated. The results show that the resins with asymmetrical side groups display better processability (wide processing window) as compared with those with symmetrical side groups. The resin with side phenyl groups shows higher flexural strength but lower thermal stability as compared with those without side phenyl groups. Meanwhile, the side phenyl groups also enhance the temperature at which secondary relaxation occurs.

The synthesis and characterization of a heat-resistant Si-containing aryl ether arylacetylene resin

A Si-containing arylether arylacetylene resin, poly(dimethylsilyene-ethynylene-phenyleneetherene-ethynylene) (PSEE), was synthesized from diethynyldiphenyl ether and dichlorosilane through Grignard reactions. The structures and properties of PSEE resin were characterized by NMR, FT-IR, DSC, TGA analysis techniques. PSEE resin can be crosslinked to form a thermoset at a temperature less than 2000C. There is no glass transition in the temperature range of RT~5000C and Td5 is 5680C in N2 for PSEE thermoset. The thermoset shows good dielectric properties and its glass fiber reinforced composite exhibits high mechanical properties. Copyright © 2017 VBRI Press.

Enhance high-temperature mechanical performance of a silicon-containing arylether arylacetylene resin with the aid of a terminal alkyne compound

Enhance high-temperature mechanical performance of a silicon-containing arylether arylacetylene resin with the aid of a terminal alkyne compound

A high-performance silicon-containing arylacetylene resin with conjugated naphthalene rings

2,7-Diphenyloxynaphthalene with large conjugated structure has been introduced into the main chain of silicon-containing arylacetylene resin and then poly(dimethylsilylene-ethynylenephenoxynaphthyloxyphenylene-ethynylene) ( m-PPNSA-MM) was synthesized. The m-PPNSA-MM resin shows good solubility and a wide processing window. A stable three-dimensional cross-linking network formed due to thermal crosslinking reactions of acetylene groups and intermolecular π–π stacking interactions after m-PPNSA-MM was cured through the process of 180°C/2 h + 220°C/2 h + 260°C/4 h. The flexural strength and modulus of the cured m-PPNSA-MM resin at room temperature are 49.2 MPa and 2.75 GPa, respectively. The cured m-PPNSA-MM resin show high thermal stabilities, the 5% temperature of weight loss ( Td5) reaches 560°C in nitrogen.

Reinforcing the poly(silylene arylacetylene)s via strong π-π stacking interactions

Silicon-containing arylacetylene resins show a trade-off between mechanical property and heat resistance as usual. A strategy is proposed by utilizing the interchain π-π stacking interactions to obtain a resin with both high mechanical property and heat resistance. In this work, silicon-containing arylacetylene resins separately with 2,5-diphenyl- [1,3,4]-oxadiazole unit as π-π stacking precursors (PODSA-MM, PODSA-MP) and the phenylene unit (PESA-MM, PESA-MP) in the main chains were synthesized by Grignard reactions. The stronger interchain π-π stacking interactions in the PODSA resins compared with PESA resins were confirmed by UV–Vis, XRD, SAXS analyses, regardless of whether or not the resins are cured. The PODSA resins with more regular structures show higher melting temperature and melt viscosity. The stable physical and chemical crosslinking dual-networks caused by both strong interchain interactions and thermal crosslinking reactions are formed in cured PODSA resins. The cured PODSA resins exhibit higher secondary relaxation temperature (Tβ), mechanical properties and thermal conductivity than cured PESA resins. The enhancement of properties of the cured PODSA resins are mainly attributed to stronger intermolecular π-π stacking interactions derived from 2,5-diphenyl- [1,3,4]-oxadiazole unit.

Highly heat‐resistant branched silicon‐containing arylacetylene resins with low curing temperature

AbstractSilicon‐containing arylacetylene (PSA) resins exhibit excellent thermal stability. However, the high curing temperature limits their applications. Herein, we report that changing the topology of PSA resins from linear to branched effectively decreases their curing temperature with no deterioration of thermal stability. Two sets of resins based on silyleneethynylene–naphthalene–ethynylene (SNP) and silyleneethynylene–phenyl–ethynylene (SPN) repeat units were studied. It is found that the branched resins exhibit considerably lower thermal curing temperatures than their linear counterparts. The exothermic peaks for branched SNP (BSNP) and branched SPN (BSPN) are about 190 and 214 °C, respectively, which are 18 and 25 °C lower than those for their linear counterparts (i.e. PSNP and PSPN). Density functional theory was applied to theoretically explain the differences in the thermal curing temperature between the linear and branched resins. The lower curing temperature of the branched PSAs is attributed to the greater number of terminal alkyne groups per molecule which increases the reactivity of the curing reaction to transform into a crosslinked structure. In addition, Td5 (the temperature at 5% mass loss) for BSNP and BSPN resins are 653 and 613 °C, respectively, which are comparable with those for their linear counterparts. © 2021 Society of Industrial Chemistry.

Enhanced Magnetic Properties of FeSiAl Soft Magnetic Composites Prepared by Utilizing PSA as Resin Insulating Layer

Thermosetting organic resins are widely applied as insulating coatings for soft magnetic powder cores (SMPCs) because of their high electrical resistivity. However, their poor thermal stability and thermal decomposition lead to a decrease in electrical resistivity, thus limiting the annealing temperature of SMPCs. The large amount of internal stress generated by soft magnetic composites during pressing must be mitigated at high temperatures; therefore, it is especially important to find organic resins with excellent thermal stabilities. In this study, we prepared SMPCs using poly-silicon-containing arylacetylene resin, an organic resin resistant to high temperatures, as an insulating layer. With 2 wt % PSA as an insulating layer and annealed at 700 °C for 1 h, the FeSiAl SMPCs achieved the best magnetic properties, including the lowest core loss of 184 mW/cm3 (measured at 0.1 T and 50 kHz) and highest permeability of 96.