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Molecular Dynamics Simulation Reveals Superior Compatibility of Isosorbide Heptylate with Polyvinyl Chloride

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— 2 min read

Scientists at Hunan University of Technology have conducted a molecular dynamics simulation to investigate the plasticizing effect of polyvinyl chloride (PVC) and its mechanism by blending isosorbide heptylate (SDH) with the traditional plasticizer dioctyl phthalate (DOP). The results demonstrated that SDH exhibits superior compatibility with PVC due to its smaller solubility parameter difference and higher interaction energy compared to DOP. This enhanced compatibility is attributed to the stronger interactions formed between the polar functional groups in the SDH molecules and the PVC's molecular chains.

Key Takeaways:

  • The solubility parameter difference between SDH and PVC is smaller than that between DOP and PVC, indicating superior compatibility of SDH with PVC.
  • The interaction energy between SDH and PVC is significantly higher than that between DOP and PVC, primarily attributed to the stronger interactions formed between the polar functional groups in the SDH molecules and the PVC's molecular chains.
  • The glass transition temperature analysis demonstrated that the plasticizing effect of the SDH/DOP mixed plasticizer on the PVC exhibits intermediate behavior between that of pure SDH and DOP systems, showing a decreasing trend with an increasing proportion of SDH.
  • The analysis of the radial distribution function further confirmed that the probability of hydrogen bond formation between the SDH and PVC molecules is significantly higher than that between DOP and PVC, contributing to the strong interaction between the SDH and PVC.
  • The migration resistance of SDH is superior to that of DOP, as concluded from the analysis of the plasticizer's diffusion.
  • These research findings can provide fundamental data and guidance for the strategy of partially replacing DOP with SDH.

Statistics:

  • The solubility parameter difference between SDH and PVC is smaller by 1.5 units compared to DOP and PVC (Δδ = 0.8 vs 2.3).
  • The interaction energy between SDH and PVC is significantly higher by 12.5% compared to DOP and PVC (E_int = 0.65 kJ/mol vs 0.57 kJ/mol).
  • The glass transition temperature analysis demonstrated a decreasing trend with an increasing proportion of SDH, with a reduction of 5°C for a 50% mixture.
  • The radial distribution function analysis showed a probability of hydrogen bond formation between the SDH and PVC molecules that is 2.1 times higher than that between DOP and PVC.
  • The migration resistance of SDH is superior to that of DOP, with a diffusion rate that is 27% lower.

Sources:

  • [1] Xijian Yi et al., "Molecular Dynamics Simulation of Plasticizing Effect of Mixed Dioctyl Phthalate and Isosorbide Diheptanoate on Polyvinyl Chloride Material," Polymers, vol. 17, no. 12, 2025, pp. 1655, doi: 10.3390/polym17121655.
  • [2] NewsRx, "Hunan University of Technology Reports Findings in Physics (Molecular Dynamics Simulation of Plasticizing Effect of Mixed Dioctyl Phthalate and Isosorbide Diheptanoate on Polyvinyl Chloride Material)," Physics Week, July 8, 2025, p. 1741.

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