Dynamic Mechanical Analysis of Polymer Thin Films Using a Kirigami-Inspired Support

Area of Science:

• Materials Science
• Polymer Science
• Mechanical Engineering

Background:

• Polymer thin films are crucial for organic photovoltaics (OPVs).
• Understanding their mechanical relaxation behavior is vital for device performance and longevity.
• Current methods may not fully capture behavior in ultra-thin films where morphology is highly sensitive to processing.

Purpose of the Study:

• To present a new method for determining the mechanical relaxation behavior of polymer thin films.
• To demonstrate the utility of a kirigami-inspired sample support for this purpose.
• To investigate the influence of processing conditions on the thermal relaxation of polymer films.

Main Methods:

• A kirigami-inspired sample support was designed and fabricated.
• Polymer thin films were placed on the kirigami support.
• The composite sample was loaded into a dynamic mechanical analyzer for tensile testing.
• Mechanical relaxation and storage modulus were quantitatively assessed.

Main Results:

• The kirigami-inspired method accurately determined the mechanical relaxation behavior of polymer thin films.
• Quantitative assessment of the film storage modulus was achieved.
• Differences in casting conditions were shown to significantly impact the thermal relaxation of neat and blend conjugated polymer films.
• The method proved valuable for thin films where morphology is highly dependent on processing.

Conclusions:

• The kirigami-inspired sample support provides an accurate method for evaluating mechanical relaxation in polymer thin films.
• This technique offers insights into how processing conditions influence film morphology and relaxation behavior.
• The findings are particularly relevant for optimizing materials used in organic photovoltaics.