Stretchable Polydimethylsiloxane Composites with Emulsified Ionic Materials and Thermochromic Applications.

In this study, a new preparation method is developed to include thermochromic complex ions in polydimethylsiloxane (PDMS) as a stretchable composite. Ethylene glycol (EG) droplets down to the nanometer scale were dispersed using a reverse micelle method to form a stable suspension in PDMS precursor solution. After curing, the EG nanodroplets were well encapsulated in the cured PDMS elastomer. The EG/PDMS composite exhibited great stability after thermal heating at 100 °C for 2 hours. The deformable liquid droplets helped maintaining the composite structures under severe stretching conditions, and thus the stretched composite exhibited great transparency without any fractures or delamination. Ionic dyes, such as methylene blue and Congo red, can be added in the EG droplets to color the composite. Moreover, complex ions with thermochromic properties can also be used in the composite. Upon thermal heating, the reconfiguration of the complex ions in the liquid dispersed phase led to obvious color changes, and the color remained unchanged up to 50% tensile strain after more than 1000 stretch cycles.