Temperature-Controlled Chain Dynamics in Polyimide Doped with CoCl₂ Probed Using Dynamic Mechanical Analysis.

Area of Science:

• Polymer Science
• Materials Chemistry
• Spectroscopy

Background:

• Polyimides are advanced polymers with applications in electronics and aerospace.
• Cobalt(II) chloride (CoCl2) is a transition metal salt with potential to modify polymer properties.
• Understanding polymer-salt interactions is crucial for developing new materials.

Purpose of the Study:

• To investigate the molecular dynamics and interactions between polyimide and CoCl2.
• To determine the influence of CoCl2 content on polyimide properties.
• To elucidate the coordination chemistry between cobalt and the polyimide matrix.

Main Methods:

• Polyimide synthesis via poly(amic acid) precursor.
• Fourier Transform Infrared Spectroscopy (FTIR) and 2D correlation spectroscopy (2D-COS) for chemical group analysis.
• X-ray photoelectron spectroscopy (XPS) for surface elemental composition and bonding.
• Dynamic Mechanical Analysis (DMA) for evaluating mechanical properties and relaxation behavior.

Main Results:

• Evidence of residual amic acid groups confirmed by FTIR and 2D-COS.
• FTIR and XPS indicated Co(II)-N coordination bonds between cobalt and polyimide.
• Coordination with amic acid groups was also observed.
• DMA revealed a specific relaxation attributed to CoCl2, with a content-dependent reinforcing effect.

Conclusions:

• CoCl2 significantly modifies polyimide molecular dynamics.
• The interaction involves Co(II)-N coordination, potentially with amic acid groups.
• The reinforcing effect of CoCl2 in polyimide is dependent on its concentration.