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<p>The effects of polymer-grafted silica nanoparticles (pg-SNPs) as both low-profile additives (LPA) and tougheners on cured sample morphologies, volume shrinkage and mechanical properties of low-shrink vinyl ester resins (VER) after cure at 120&#xa0;°C were investigated. These pg-SNPs designated as SiO<sub>2</sub>-polymer, which contain SNP as the core and organic polymer as the shell, were synthesized by the Z supported reversible addition-fragmentation chain transfer (RAFT) graft polymerization using silica-supported 3-(benzylsulfanylthiocarbonylsulfanyl) propionic acid (Si-BSPA) as the chain transfer agent (CTA). The 15&#xa0;nm SNP was synthesized by size-controllable hydrolysis of elemental silicon, whereas the grafted polymer onto SiO<sub>2</sub> was made from poly(butyl acrylate)-block-poly(methyl acrylate-co-glycidyl methacrylate) (PBA-b-poly(MA-co-GMA)) with molecular weights (M<sub>n</sub>) at about 40,000&#xa0;g/mol. Depending on the content of pg-SNP (0–15 wt%), and the molar composition of GMA (0–20&#xa0;mol%) in outer shell of pg-SNP, the pg-SNP could lead to a reduction of cyclization reaction for VER resins during the cure, and the microgel structure during the cure would be less compact, and, in turn, be favorable for the decrease of intrinsic polymerization shrinkage after the cure. It was found that adding 15 wt% SiO<sub>2</sub>-PBA-b-poly(MA-co-GMA20)-40&#xa0;K, with 20&#xa0;mol% GMA in outer shell, can lead to a decrease of volume shrinkage by about 84%. As for the mechanical properties of cured St/VER/pg-SNP ternary systems, adding 15 wt% SiO<sub>2</sub>-PBA-b-poly(MA-co-GMA20)-40&#xa0;K may lead to an increase of the impact strength by 142%, an increase of Young’s modulus by 30%, but a slight decrease of tensile strength by 23%, when compared with that of neat cured St/VER resin.</p>

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Synthesis of polymer-grafted silica nanoparticles by RAFT polymerization and their effects on the volume shrinkage and mechanical properties of cured vinyl ester resins

  • 期刊论文

  • 发表日期：

    2025年11月22日

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  • Woan-Luen Chung,
  • Meng-Ru Chung,
  • Jyh-Woei Huang,
  • Yueh-Pyn Lin,
  • Yan-Jyi Huang

摘要

The effects of polymer-grafted silica nanoparticles (pg-SNPs) as both low-profile additives (LPA) and tougheners on cured sample morphologies, volume shrinkage and mechanical properties of low-shrink vinyl ester resins (VER) after cure at 120 °C were investigated. These pg-SNPs designated as SiO2-polymer, which contain SNP as the core and organic polymer as the shell, were synthesized by the Z supported reversible addition-fragmentation chain transfer (RAFT) graft polymerization using silica-supported 3-(benzylsulfanylthiocarbonylsulfanyl) propionic acid (Si-BSPA) as the chain transfer agent (CTA). The 15 nm SNP was synthesized by size-controllable hydrolysis of elemental silicon, whereas the grafted polymer onto SiO2 was made from poly(butyl acrylate)-block-poly(methyl acrylate-co-glycidyl methacrylate) (PBA-b-poly(MA-co-GMA)) with molecular weights (Mn) at about 40,000 g/mol. Depending on the content of pg-SNP (0–15 wt%), and the molar composition of GMA (0–20 mol%) in outer shell of pg-SNP, the pg-SNP could lead to a reduction of cyclization reaction for VER resins during the cure, and the microgel structure during the cure would be less compact, and, in turn, be favorable for the decrease of intrinsic polymerization shrinkage after the cure. It was found that adding 15 wt% SiO2-PBA-b-poly(MA-co-GMA20)-40 K, with 20 mol% GMA in outer shell, can lead to a decrease of volume shrinkage by about 84%. As for the mechanical properties of cured St/VER/pg-SNP ternary systems, adding 15 wt% SiO2-PBA-b-poly(MA-co-GMA20)-40 K may lead to an increase of the impact strength by 142%, an increase of Young’s modulus by 30%, but a slight decrease of tensile strength by 23%, when compared with that of neat cured St/VER resin.