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<p>A high-performance polysiloxane nanocomposite adhesive was developed using a backbone engineered with methylvinyl and diphenyl units to enable addition curing and enhance thermal and mechanical stability. The poly(dimethyl-co-diphenyl) siloxane copolymer and poly(dimethyl-co-diphenyl-co-methylvinyl) siloxane terpolymer were synthesized via tetramethylammonium silanolate-initiated anionic ring-opening polymerization. A central innovation of this study is the replacement of conventional volatile small-molecule disiloxane end-cappers with a long-chain vinyl-terminated end-capper. This molecular engineering strategy overcomes a key limitation of equilibrium anionic polymerization—namely, poor molecular weight predictability at medium-to-high molecular weights—while simultaneously enhancing curing efficiency by providing higher effective vinyl functionality at the chain ends. The resulting polysiloxanes were formulated into a two-part adhesive by incorporating fumed silica and iron oxide nanoparticles, leading to enhanced mechanical performance and interfacial adhesion. Careful purification and optimized synthesis minimized unreacted species, yielding an adhesive with a tensile strength of 1.4 MPa, an elastic modulus of 942 MPa, an elongation at break of 143%, and a single-lap shear strength of 1.3 MPa. Notably, the adhesive exhibited an ultra-low total mass loss (TML) of 0.181%, highlighting its strong potential for use in advanced electronic and aerospace systems, where mechanical robustness and low outgassing are critical.</p>

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Synthesis of molecularly engineered polysiloxane nanocomposites adhesive enabled by long-chain end-capping and synergistic silica/iron oxide reinforcement

  • 期刊论文

  • 发表日期：

    2026年2月28日

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  • Mahdi Hashemi,
  • Ehsan Chehrazi,
  • Majid Haghgoo,
  • Majid Mokhtari

摘要

A high-performance polysiloxane nanocomposite adhesive was developed using a backbone engineered with methylvinyl and diphenyl units to enable addition curing and enhance thermal and mechanical stability. The poly(dimethyl-co-diphenyl) siloxane copolymer and poly(dimethyl-co-diphenyl-co-methylvinyl) siloxane terpolymer were synthesized via tetramethylammonium silanolate-initiated anionic ring-opening polymerization. A central innovation of this study is the replacement of conventional volatile small-molecule disiloxane end-cappers with a long-chain vinyl-terminated end-capper. This molecular engineering strategy overcomes a key limitation of equilibrium anionic polymerization—namely, poor molecular weight predictability at medium-to-high molecular weights—while simultaneously enhancing curing efficiency by providing higher effective vinyl functionality at the chain ends. The resulting polysiloxanes were formulated into a two-part adhesive by incorporating fumed silica and iron oxide nanoparticles, leading to enhanced mechanical performance and interfacial adhesion. Careful purification and optimized synthesis minimized unreacted species, yielding an adhesive with a tensile strength of 1.4 MPa, an elastic modulus of 942 MPa, an elongation at break of 143%, and a single-lap shear strength of 1.3 MPa. Notably, the adhesive exhibited an ultra-low total mass loss (TML) of 0.181%, highlighting its strong potential for use in advanced electronic and aerospace systems, where mechanical robustness and low outgassing are critical.