<p>Thermodynamic modelling was conducted using compressible self-consistent field theory to predict the morphology of polyurethane (PU)/clay nanocomposites. The PU comprised of poly(tetramethylene ether)glycol, as its soft segment, and methylene bis(cyclohexyl) diisocyanate-butanediol-methylene bis(cyclohexyl) diisocyanate, as its hard segment. The effect of polyol molecular weight, degree of polymerization of PU, nanoparticle volume fraction, solubility parameter of nanoparticle, and temperature on the free energy of the system was investigated. At 25&#xa0;°C, a tenfold increase in the molecular weight of the polyol from 1000 to 10,000&#xa0;g/mol in a PU nanocomposite containing clay with a solubility parameter of 24.4 (J/cm<sup>3</sup>)<sup>1/2</sup> at a volume fraction of 0.05 led to 56% drop in the free energy per unit area of the system. In similar conditions regarding temperature and the solubility parameter of clay, with a fivefold increase in the polymerization degree of a PU comprised of a polyol with a molecular weight of 1000&#xa0;g/mol, from 10 to 50, a 110% reduction in the free energy per unit area was observed. Raising the nanoparticle volume fraction from 0.05 to 0.1 and reducing the solubility parameter of the nanoparticle from 24.4 to 17.7 (J/cm<sup>3</sup>)<sup>1/2</sup> decreased the free energy per unit area. Furthermore, with an increase in the temperature from 25 to 190&#xa0;°C and thus, with the thermal expansion of the polymer and the dilution of their interactions with the nanoparticle, the free energy per unit area increased. The results showed an ordered exfoliated morphology for the nanocomposite systems, in good agreement with the experimental results.</p> Graphical abstract <p></p>

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Morphological predictions of polyurethane/clay nanocomposite systems by compressible self-consistent field theory

  • Gohar Mohammadi,
  • Somayeh Ghasemirad,
  • Mehrdad Kokabi

摘要

Thermodynamic modelling was conducted using compressible self-consistent field theory to predict the morphology of polyurethane (PU)/clay nanocomposites. The PU comprised of poly(tetramethylene ether)glycol, as its soft segment, and methylene bis(cyclohexyl) diisocyanate-butanediol-methylene bis(cyclohexyl) diisocyanate, as its hard segment. The effect of polyol molecular weight, degree of polymerization of PU, nanoparticle volume fraction, solubility parameter of nanoparticle, and temperature on the free energy of the system was investigated. At 25 °C, a tenfold increase in the molecular weight of the polyol from 1000 to 10,000 g/mol in a PU nanocomposite containing clay with a solubility parameter of 24.4 (J/cm3)1/2 at a volume fraction of 0.05 led to 56% drop in the free energy per unit area of the system. In similar conditions regarding temperature and the solubility parameter of clay, with a fivefold increase in the polymerization degree of a PU comprised of a polyol with a molecular weight of 1000 g/mol, from 10 to 50, a 110% reduction in the free energy per unit area was observed. Raising the nanoparticle volume fraction from 0.05 to 0.1 and reducing the solubility parameter of the nanoparticle from 24.4 to 17.7 (J/cm3)1/2 decreased the free energy per unit area. Furthermore, with an increase in the temperature from 25 to 190 °C and thus, with the thermal expansion of the polymer and the dilution of their interactions with the nanoparticle, the free energy per unit area increased. The results showed an ordered exfoliated morphology for the nanocomposite systems, in good agreement with the experimental results.

Graphical abstract