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<p>This study reports the development of a novel curing route for fabricating silicone elastomers based on hydride-functionalized silicone copolymers. The work was conducted in three parts. First, copolymers were synthesized via cationic ring-opening polymerization under varying conditions, including different temperatures and dimethylsiloxy (D) to methylhydrosiloxy (D<sup>H</sup>) unit ratios, to examine their effects on key parameters such as yield and practical molecular weight. While the yield remained relatively constant (90–93%) regardless of temperature, increasing the temperature to 95&#xa0;°C raised the D/D<sup>H</sup> ratio from the targeted value 3 to 4.2. Additionally, decreasing the D/D<sup>H</sup> ratio from 9 to 1 resulted in an approximate 20% reduction in the experimentally measured molecular weight compared to the targeted value. After optimizing the reaction conditions, copolymers with different molecular weight and D/D<sup>H</sup> were synthesized, and their curing behavior was studied at different platinum catalyst concentrations and temperatures. Results showed that the sequence of D and D<sup>H</sup> units greatly influences the curing temperature. Random copolymers cured at 100&#xa0;°C within ~ 50&#xa0;min, whereas PMHS, with its high Si–H content and blocky D<sup>H</sup> sequences, did not cure at this temperature, and copolymers containing D<sup>H</sup> blocks required at least 130&#xa0;°C to achieve a comparable curing rate. Moreover, increasing the concentration of Si–H groups moderately accelerated the curing rate. Finally, nanocomposites were fabricated by incorporating different amounts of hydrophobic fumed silica, and their thermal and mechanical properties were evaluated. The best performance was observed at 5&#xa0;wt% nanofiller, showing an onset degradation temperature around 360&#xa0;°C, a tensile strength of 1380&#xa0;kPa, and stretchability up to 140%. The elastomers' properties were benchmarked against commercial addition-cure silicone rubbers (ALSRs). Overall, the results indicate that PMHS-co-PDMS-based elastomers exhibit thermal and mechanical properties comparable to those of ALSRs in many cases. Such materials open new prospects for applications requiring rapid processing, reduced filler loadings, and cost-effective production.</p>

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Fabrication of silicone elastomers and their silica nanocomposites from hydride-functionalized copolymers: preparation and properties

  • 期刊论文

  • 发表日期：

    2025年10月26日

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  • Ali Rahmatpour,
  • Mohammad Hossein Jazayeri

摘要

This study reports the development of a novel curing route for fabricating silicone elastomers based on hydride-functionalized silicone copolymers. The work was conducted in three parts. First, copolymers were synthesized via cationic ring-opening polymerization under varying conditions, including different temperatures and dimethylsiloxy (D) to methylhydrosiloxy (DH) unit ratios, to examine their effects on key parameters such as yield and practical molecular weight. While the yield remained relatively constant (90–93%) regardless of temperature, increasing the temperature to 95 °C raised the D/DH ratio from the targeted value 3 to 4.2. Additionally, decreasing the D/DH ratio from 9 to 1 resulted in an approximate 20% reduction in the experimentally measured molecular weight compared to the targeted value. After optimizing the reaction conditions, copolymers with different molecular weight and D/DH were synthesized, and their curing behavior was studied at different platinum catalyst concentrations and temperatures. Results showed that the sequence of D and DH units greatly influences the curing temperature. Random copolymers cured at 100 °C within ~ 50 min, whereas PMHS, with its high Si–H content and blocky DH sequences, did not cure at this temperature, and copolymers containing DH blocks required at least 130 °C to achieve a comparable curing rate. Moreover, increasing the concentration of Si–H groups moderately accelerated the curing rate. Finally, nanocomposites were fabricated by incorporating different amounts of hydrophobic fumed silica, and their thermal and mechanical properties were evaluated. The best performance was observed at 5 wt% nanofiller, showing an onset degradation temperature around 360 °C, a tensile strength of 1380 kPa, and stretchability up to 140%. The elastomers' properties were benchmarked against commercial addition-cure silicone rubbers (ALSRs). Overall, the results indicate that PMHS-co-PDMS-based elastomers exhibit thermal and mechanical properties comparable to those of ALSRs in many cases. Such materials open new prospects for applications requiring rapid processing, reduced filler loadings, and cost-effective production.