ORGS3-1113
Thermomechanical properties of free-standing polymer thin films on an ionic liquid surface at low temperatures via a novel direct testing method
Topic
GS3. Graduate Student Oral Session III: Polymer Synthesis, Structure, Properties, and Processing
When and Where
Sep 28, 2026
16:12 - 16:24
Room 103
Session Chairs
Jiwon KIM
Junmin LEE
Youngwoon KO
Presenter(s)
Eun Sung Oh (KAIST)
Co-Author(s)
Abstract
Polymer thin films have widely used for wearable electronics due to mechanical advantages such as low Young’s modulus and high stretchability. Considering that wearable electronic devices must operate in outdoor environments while attached to the human body or clothing, the polymer thin films are generally exposed to low temperatures down to -10 °C. Since polymers exhibit brittle mechanical behavior with reducing temperature, the thermomechanical properties of the polymer thin films at low temperatures are critical for the mechanical reliability of the wearable devices. However, it is highly challenging to measure the thermomechanical properties due to intrinsic fragility of the polymer thin films in free-standing state and the absence of the cooling system for the films. In this work, we measure the thermomechanical properties of free-standing polymer thin films on an ionic liquid surface at low temperatures down to -10 °C, developing direct thermomechanical testing using a Peltier device. While Young’s modulus of polystyrene (PS) thin films decreases linearly from -10 °C to 25 °C, the films exhibit a sharp increase in crack on-set strain (COS) due to slow propagation of voids inside crazing zone. And it is revealed that the tensile and thermal expansion properties of regiorandom poly(3-hexylthiophene) (RRa P3HT) thin films change sharply across glass transition temperature (Tg). This work highlights the significance of low-temperature properties of the polymer thin films for the mechanical reliability of wearable electronics, proposing a novel direct thermomechanical testing method at low temperatures.
