Mechanical and Optical Properties of Stretchable Silicon Nanocrystal/Polydimethylsiloxane Nanocomposites

Nanoparticle-infused polymer composites have long been an area of interest due to the typically stabilizing effects they have on the mechanical behavior of the composites, as well as added functionalities such as reduced surface resistance. Newer applications of these nanocomposites include dispersing optoelectronically functional nanoparticles in polymer matrices, for example, including luminescent nanocrystals in rigid slabs for luminescent solar concentrating photovoltaics and electrochromic panels. Dispersion of luminescent nanocrystals in stretchable polymers adds novel possibilities for applications, such as wearable health monitoring systems, flexible communications devices, and more. To leverage the exciting combined properties that these nanocomposites promise, there is a pressing need to evaluate and understand the interconnections between the optical effects, mechanical behavior, and the properties of the constituents. Herein, the optical and mechanical behavior of brightly emissive silicon nanocrystal/polydimethylsiloxane (PDMS) nanocomposites are investigated as a function of nanocrystal concentration and nanocrystal surface functionality. Mechanically, incorporating the nanocrystals at higher concentration leads to a dramatic reduction in the mechanical properties of the nanocomposite. The results suggest that the nanocrystal inclusions interfere with polymer cross-linking, changing the mechanical behavior of the host PDMS as compared to the control.