Mechanochromic blends

Although the property of interest in all of the above-mentioned cyano-OPV-containing materials was a mechanically induced change of the photoluminescence color (i.e., a mechanically induced transformation from an excimer-rich to a monomer-dominated emission), certain cyano-OPVs also display a changed of their absorption color upon (dis)assembly. Thus, Kunzelman et al. reported mechanochromic blend films based on C18-RG and either poly(ethylene... 

Figure 11.10 Deformation induced colour changes in mechanochromic blends.

As many authors suggest, mechanochromic blends may find numerous applications, e.g., as strain sensors or as built-in threshold temperature sensors in polymer-based materials, therefore representing a promising technology for the production of devices with security purposes. 

Crenshaw, B.R, Burnworth, M., Khariwala, D Hiltner, A., Mather, P. T., Simha, R., Weder, C., Deformation-induced color changes in mechanochromic polyethylene blends. Macromolecules, 40(7), pp. 2400-2408 (2007). 

These blends have been used for the fabrication of luminogenic mechanochromic thin films. Which films change their emission color upon deformation. The alkyl tails influence fhe solubilify of fhe chromophores in the polymer matrix and effect different aggregation properties. Thus, the mechanochromic fluorescence color change of the blends is related to the self-assembly of the excimer-forming dye in the unperturbed polymer matrix. 

---