Research ArticleMATERIALS SCIENCE

Optically transparent, high-toughness elastomer using a polyrotaxane cross-linker as a molecular pulley

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Science Advances  12 Oct 2018:
Vol. 4, no. 10, eaat7629
DOI: 10.1126/sciadv.aat7629
  • Fig. 1 Comparison of mechanical properties of elastomers prepared using polyrotaxane cross-linking agent and general cross-linking agent.

    (A) Stress-extension ratio curves of the MEO2MA elastomers prepared with HPR-C and EGDMA as cross-linkers. (B) The horizontal axis of (A) was converted to λ-λ−2 to analyze the results of (A). On the basis of the linear relationship observed in (B), the polymer between the cross-linking points behaves as a Gaussian chain. (C) Hysteresis loops of the stress-extension ratio curves of the MEO2MA elastomers prepared with HPR-C and EGDMA as cross-linkers.

  • Fig. 2 Comparison of thermophysical properties of elastomers prepared using polyrotaxane cross-linking agent and general cross-linking agent.

    (A) DSC results of the MEO2MA elastomers prepared with HPR-C and EGDMA as cross-linkers. (B) TGA of the MEO2MA elastomers prepared with HPR-C and EGDMA as cross-linkers. (C) Temperature dependence of the storage modulus, loss elastic modulus, and tan δ obtained from the dynamic viscoelasticity measurements of the MEO2MA elastomers prepared with HPR-C and EGDMA as cross-linkers.

  • Fig. 3 SAXS analysis of the behavior of polyrotaxane in elastomers.

    Scattering profiles obtained by SAXS measurements of the MEO2MA elastomers prepared with HPR-C and EGDMA as cross-linkers: (A) Elastomers prepared with different amounts of HPR-C or with EGDMA. (B) The scattering profiles of the elastomers containing different amounts of HPR-C in (A) were normalized to the concentration of HPR-C. (C) 2D SAXS pattern obtained during uniaxial stretching of the MEO2MA elastomer prepared with 2 wt % HPR-C as a cross-linker. (D) Sector-averaged scattering profiles, I(Q), for the direction parallel to the deformation of the MEO2MA elastomer prepared with 2 wt % HPR-C. (E) Schematic diagram of the change in the conformation of PR due to elongation of the elastomer. The arrow in the figure indicates the elongation direction of the elastomer.

  • Fig. 4 Mechanical properties of polyrotaxane cross-linked elastomers at various polyrotaxane concentrations.

    (A) Results of the uniaxial tensile tests and tear tests of the MEO2MA elastomers prepared with different amounts of HPR-C as a cross-linker. (B) Temperature dependence of the storage modulus of the MEO2MA elastomers prepared with different amounts of HPR-C or with EGDMA. (C) Temperature dependence of the loss modulus of the MEO2MA elastomers prepared with different amounts of HPR-C or with EGDMA. (D) Temperature dependence of tan δ of the MEO2MA elastomers prepared with different amounts of HPR-C or with EGDMA.

  • Fig. 5 Chemical structure of the cross-linkers (HPR-C and EGDMA) and monomer (MEO2MA) used in this study.

    Here, only two cyclic cyclodextrin molecules are shown, in order to simplify the diagram.

  • Table 1 Fracture energy (Γ) of 1.0 wt % HPR-C and EGDMA elastomers.
    EGDMA1.0 wt % HPR-C
    Strain energy density U (kPa)20.2102.2
    Fracture energy Γ (J/m2)147.8703.1
  • Table 2 Mechanical properties obtained from the uniaxial tests of the MEO2MA elastomers prepared with different amounts of HPR-C as a cross-linker.
    0.5 wt %
    HPR-C
    1.0 wt %
    HPR-C
    2.0 wt %
    HPR-C
    4.0 wt %
    HPR-C
    Young’s modulus E
    (kPa)
    125280349400
    Extension at break λ
    (mm/mm)
    760620615481
    U (kPa)70.8102.2138.3145.9
    Γ (J/m2)415.9703.11019.11320.2

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/10/eaat7629/DC1

    Table S1. Preparation of MEO2MA elastomer with HPR-C with varying amounts of monomer-to-solvent ratio.

    Table S2. Preparation of MEO2MA elastomer with HPR-C with varying amounts of HPR-C concentration.

    Table S3. Preparation of MEO2MA elastomer with EGDMA with varying amounts of monomer to solvent ratio.

    Scheme S1. Elastomer shapes used for the mechanical tests.

    Fig. S1. Viscoelasticity dynamics of polyrotaxane cross-linked elastomers at various polyrotaxane concentrations.

    Fig. S2. Stress-extension ratio curves of PR–cross-linked elastomer (PR concentration, 1 wt %) under loading-unloading process at various strain rates.

    Fig. S3. Young’s moduli of elastomers with various HPR-C cross-linker concentrations.

    Fig. S4. Photos of the HPR-C–cross-linked MEO2MA elastomer exhibiting a reversible extensibility change.

  • Supplementary Materials

    This PDF file includes:

    • Table S1. Preparation of MEO2MA elastomer with HPR-C with varying amounts of monomer-to-solvent ratio.
    • Table S2. Preparation of MEO2MA elastomer with HPR-C with varying amounts of HPR-C concentration.
    • Table S3. Preparation of MEO2MA elastomer with EGDMA with varying amounts of monomer to solvent ratio.
    • Scheme S1. Elastomer shapes used for the mechanical tests.
    • Fig. S1. Viscoelasticity dynamics of polyrotaxane cross-linked elastomers at various polyrotaxane concentrations.
    • Fig. S2. Stress-extension ratio curves of PR–cross-linked elastomer (PR concentration, 1 wt %) under loading-unloading process at various strain rates.
    • Fig. S3. Young’s moduli of elastomers with various HPR-C cross-linker concentrations.
    • Fig. S4. Photos of the HPR-C–cross-linked MEO2MA elastomer exhibiting a reversible extensibility change.

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