Mechanochromic polymers are an emerging class of stimuli-responsive materials that can be used in a variety of industrial applications, such as the detection of mechanical damage or pressure sensors. The encapsulation of charge-transfer complexes (CTCs) to create mechanochromic materials is reported here. Hexamethylbenzene (donor) and chloranil (acceptor) were separately encapsulated in poly(urea-formaldehyde) microcapsules. These capsules were dispersed in a poly(dimethylsiloxane) (PDMS) pre-polymer, which was subsequently cured to produce the desired mechanoresponsive elastomers. When local stresses were applied to the materials, the microcapsules broke, releasing the donor and acceptor molecules, which led to the formation of a CTC and, ultimately, to a remarkable yellow-to-red color change (Figure 1). These composite structures responded under different type of stress: shearing, stretching and compression. This work demonstrates a novel strategy to fabricate mechanochromic materials by means of a straightforward and scalable methodology, which could potentially be extended to other matrices and optical systems.

Encapsulation of charge-transfer complexes for mechanochromic sensors applications

249th National Meeting (2015)

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