Non-equilibrium segmental dynamics driven by multiwall carbon nanotubes in PS/PVME blends

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Dynamically asymmetric polymer blends like polystyrene/poly(vinyl methyl ether) (PS/PVME) exhibit complex structural relaxation and intermolecular cooperativity.
• Understanding how nanofillers influence these properties is crucial for designing advanced materials.

Purpose of the Study:

• To investigate the effect of multiwall carbon nanotubes (MWNTs) on structural relaxation and intermolecular cooperativity in PS/PVME blends.
• To explore the role of MWNTs in miscibility, dynamics, and phase separation behavior.

Main Methods:

• Dielectric spectroscopy (DS) was employed to study relaxation dynamics in the temperature regime where chain connectivity effects dominate.
• Calorimetric measurements were used to assess the length scale of the cooperative rearranging region (ξCRR) at the glass transition temperature (Tg).

Main Results:

• MWNTs induced a bimodal relaxation distribution in the loss modulus spectra, suggesting altered environments for PVME.
• PVME segmental dynamics were significantly slowed by MWNTs, exhibiting Arrhenius-type behavior attributed to interphase regions.
• The ξCRR at Tg increased in the presence of MWNTs, indicating enhanced molecular-level miscibility and larger cooperative volumes.

Conclusions:

• MWNTs promote enhanced miscibility and alter relaxation dynamics in PS/PVME blends.
• Phase separation via spinodal decomposition led to an interconnected PVME network, resulting in materials with high electrical conductivity.