Surface characterisation of plasma-modified poly(ethylene terephthalate)

Area of Science:

• Materials Science
• Surface Chemistry
• Polymer Science

Background:

• Polyethylene terephthalate (PET) is a widely used polymer.
• Surface modification of PET can enhance its properties for various applications.
• Cold plasma treatments offer a non-thermal method for polymer surface modification.

Purpose of the Study:

• To investigate the surface modifications of PET induced by nitrogen and helium cold plasmas.
• To analyze the chemical and morphological changes on the PET surface.
• To evaluate the impact of plasma treatments on the surface free energy of PET.

Main Methods:

• Diffuse reflectance Fourier transform spectroscopy (DRIFTS) for chemical analysis.
• Atomic force microscopy (AFM) for surface morphology.
• Inverse gas-solid chromatography (IGSC) for surface energy determination.

Main Results:

• Plasma treatments introduced nitrogen and oxygen atoms onto the PET surface.
• AFM revealed surface alterations, including the formation of bumps due to polymer chain scission.
• Surface area and porosity remained unchanged after plasma treatments up to 15 minutes.
• Nitrogen plasma decreased the dispersive component of surface free energy (gamma(s)(d)) with prolonged treatment.
• Helium plasma showed minimal change in gamma(s)(d) even after extended treatment.

Conclusions:

• Cold plasma treatments effectively modify the PET surface chemistry and morphology.
• The observed surface changes are dependent on the type of plasma gas (nitrogen vs. helium) and treatment duration.
• PET surface energy can be tuned by plasma treatment, with nitrogen plasma showing a more significant effect on the dispersive component.