Structure–Thermal Property Relationships of Polysilsesquioxanes for Thermal Insulation Materials

Hamada, Takashi; Goto, Taku; Takase, Sakino; Okada, Kenta; Uedono, Akira; Ohshita, Joji

doi:10.1021/acsapm.1c01812

Cited by 10 publications

(13 citation statements)

References 29 publications

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“…Indeed, M w linearly increased with the increase in the water/monomer molar ratio (Figure ), indicating that the molecular weight of PGPS could be controlled by varying the amount of water. This trend is consistent with the hydrolysis and polycondensation of bis(triethoxysilyl)ethane and triethoxymethylsilane by the nitrogen flow method. ,, …”

Section: Resultssupporting

confidence: 85%

“…PGPS was synthesized by hydrolysis and polycondensation by the nitrogen flow method, as illustrated in Scheme . The nitrogen flow method is useful for controlling the molecular weight of PSQ by changing the water/monomer molar ratio, as reported in previous studies. − ,, Therefore, PGPS samples were synthesized by changing the water/monomer molar ratio to obtain a polymer with different molecular weights, as illustrated in Table . With a water/monomer molar ratio of 1.2, the weight-average molecular weight ( M w ) and polydispersity index ( M w / M n ) of PGPS were 5200 and 2.0, respectively (entry 1 in Table ).…”

Section: Resultsmentioning

confidence: 99%

“…PSQs with different molecular weights were synthesized according to the procedure described in previous studies. − In a typical synthesis using a water/monomer molar ratio of 1.2, 3-glycidyloxypropyltrimethoxysilane (4.727 g and 20.00 mmol) and methanol (6.408 g and 200.0 mmol) were added to a 100 mL four-necked flask equipped with a mechanical stirrer and a nitrogen inlet and outlet. The flask was placed in an ice-water bath, and the solution was stirred for 10 min with a rotation speed of 150 rpm.…”

Section: Methodsmentioning

confidence: 99%

“…This trend is consistent with the hydrolysis and polycondensation of bis(triethoxysilyl)ethane and triethoxymethylsilane by the nitrogen flow method. 41,43,46 Preparation of the PSQ-OH Film via Route A. Two routes were designed for the preparation of the PSQ-OH films (Figure 3).…”

Section: ■ Introductionmentioning

confidence: 99%

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Robust and Transparent Antifogging Polysilsesquioxane Film Containing a Hydroxy Group

et al. 2022

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Poly(glycidyloxypropyl)silsesquioxane (PGPS) was successfully synthesized by hydrolysis and polycondensation using the nitrogen flow method. A poly(3-(2,3-dihydroxypropoxypropyl)silsesquioxane) (PSQ-OH) film was prepared via two routes. In route A, PSQ-OH was prepared by the hydrolysis of the epoxy group of PGPS in an aqueous hydrochloric acid (HCl)/tetrahydrofuran solution, affording a diol group; then, PSQ-OH was coated on a glass substrate and heated. The antifogging performance of the PSQ-OH film was evaluated in terms of water uptake (WU) and scratch resistance. The obtained PSQ-OH film exhibited a low WU of 5% and a scratch resistance of 1.6. In route B, PGPS was coated on a glass substrate and immersed in a 0.5 mol/L aqueous sulfuric acid solution for 1–15 h at room temperature, producing a diol group. The solid-state 13C nuclear magnetic resonance spectrum indicated that the epoxy group was completely hydrolyzed after immersion for 15 h. The WU of the PSQ-OH film prepared via route B increased from 5 to 19% with the increase in the immersion time and was higher than that of the PSQ-OH film prepared via route A. The PSQ-OH film on a glass substrate retained transparency under water vapor exposure at 60 °C. The PSQ-OH film prepared via route B exhibited a high scratch resistance of 2.7–3.6, similar to that of a poly(3-(2-aminoethylaminopropyl)silsesquioxane) film. The scratch resistance of the PSQ-OH film was 5–7 times higher than that of the poly(vinyl alcohol) film. The PSQ-OH film was uniform with no pinholes and cracks. The PSQ-OH film was transparent and colorless and exhibited a high transmittance of >90% in the wavelength range of 400–800 nm. Overall, the prepared PSQ-OH film exhibits good antifogging, transparency, and mechanical properties.

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Robust and Transparent Antifogging Polysilsesquioxane Film Containing a Hydroxy Group

et al. 2022

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“…To demonstrate the convenience of using MSQ-SiH to prepare the MSQ/TAIC hybrid films by hydrosilylation reaction, we prepared a PSQ film containing the isocyanurate ring by the polycondensation reaction of a polymethylsilsesquioxane having a molecular weight similar to that of MSQ-SiH (M w = 1200) and TESIC as a control experiment. First, we synthesized the polymethylsilsesquioxane by the sol−gel reaction of triethoxymethylsilane according to our previous paper 24 and TESIC by the hydrosilylation reaction of TAIC with triethoxysilane (Scheme 2). The 1 H NMR and HRMS of the as-prepared TESIC confirmed that it was obtained in high purity by simply removing the solvent from the reaction mixture under high vacuum.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Organic–Inorganic Hybrid Thermal Insulation Materials Prepared via Hydrosilylation of Polysilsesquioxane Having Hydrosilyl Groups and Triallylisocyanurate

Takase

Hamada

Okada

et al. 2022

ACS Appl. Polym. Mater.

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In the quest for efficient thermal insulation materials, enhancing the thermal insulation property of polysilsesquioxanes (PSQs) by introducing crosslinkers is a promising strategy. In this study, organic−inorganic hybrid films containing isocyanurate rings in the PSQ network were prepared by the hydrosilylation reaction of hydrodimethylsilylated oligomethylsilsesquioxane (MSQ-SiH) and triallylisocyanurate (TAIC) as a crosslinker in the presence of Karstedt's catalyst. The formation of the MSQ/TAIC hybrid films was confirmed by attenuated total reflection Fourier transform infrared spectroscopy and 13 C and 29 Si solid-state nuclear magnetic resonance spectroscopy. The obtained MSQ/TAIC hybrid films were colorless, transparent, and stiff, regardless of the amount of TAIC in the PSQ network. The thermal diffusivity of the MSQ/TAIC hybrid films (1.01 × 10 −7 −1.14 × 10 −7 m 2 /s) was lower than that of an MSQ film (1.44 × 10 −7 m 2 /s) prepared by the oxidative homocoupling reaction of MSQ-SiH and a PSQ/tris(3-triethoxysilylpropyl)isocyanurate (TESIC) film (1.25 × 10 −7 m 2 /s) prepared by the polycondensation reaction of ethoxy-and hydroxy-containing polymethylsilsesquioxane and tris(3-triethoxysilylpropyl)isocyanurate (TESIC). A positron annihilation lifetime analysis indicated that the decrease in thermal diffusivity was due to the nature of the TAIC structure rather than to the formation of intramolecular void spaces. Thermogravimetric measurements revealed that the MSQ/TAIC hybrid films were thermally less stable than the MSQ film but more stable than the PSQ/TESIC film and previously reported TAIC-containing polymer films, which demonstrates that MSQ-SiH is a suitable oligomer for the preparation of hybrid materials with high thermal stability.

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Influence of alkyl groups on the formation of softenable polysilsesquioxanes

Pohl

Kickelbick

2023

J Sol-Gel Sci Technol

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Polysilsesquioxanes (PSQ) containing phenyl groups as substituents on the silicon atom can form transparent, hard and glassy materials at room temperature, which reversibly soften when heated above the glass transition temperature. Further increase in temperature leads to irreversible curing. With this property, polyphenylsilsesquioxanes can be assigned to the so-called melting gels. In contrast to the aromatic systems, polysilsesquioxanes with alkyl groups belonging to this class of materials are not known. To identify structural differences between aryl and alkyl systems, polyalkylsilsesquioxanes (RPSQs with R = methyl, ethyl, propyl, hexyl, octyl, decyl, dodecyl, hexadecyl, and octadecyl) were synthesised by a solvent-free, acid-catalysed hydrolysis and condensation reaction of alkyltrimethoxysilanes followed by thermal treatment at 300 °C under N2 atmosphere. The influence of the alkyl chain length on the structure built and the thermally initiated further condensation reactions were investigated via NMR, FTIR, TGA, DSC, SEC, and XRD. Depending on the alkyl chain length, the formation of highly crosslinked, insoluble systems (Me-PrPSQ), low molecular weight oligosilsesquioxanes in the form of cages (Hex-DecPSQ) to semicrystalline, lamellar layers (Dodec-OctadecPSQ) were detected. A low degree of condensation, inhibition of self-assembly and preferentially intermolecular condensation reactions were found to be crucial factors in the melting gel formation. Graphical Abstract

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Structure–Thermal Property Relationships of Polysilsesquioxanes for Thermal Insulation Materials

Cited by 10 publications

References 29 publications

Robust and Transparent Antifogging Polysilsesquioxane Film Containing a Hydroxy Group

Robust and Transparent Antifogging Polysilsesquioxane Film Containing a Hydroxy Group

Organic–Inorganic Hybrid Thermal Insulation Materials Prepared via Hydrosilylation of Polysilsesquioxane Having Hydrosilyl Groups and Triallylisocyanurate

Influence of alkyl groups on the formation of softenable polysilsesquioxanes

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