Triggered Metal Ion Release and Oxidation: Ferrocene as a Mechanophore in Polymers

The introduction of mechanophores into polymers makes it possible to transduce mechanical forces into chemical reactions that can be used to impart functions such as self-healing, catalytic activity, and mechanochromic response. Here, an example of mechanically induced metal ion release from a polymer is reported. Ferrocene (Fc) was incorporated as an iron ion releasing mechanophore into poly(methyl acrylate)s (PMAs) and polyurethanes (PUs). Sonication triggered the preferential cleavage of the polymers at the Fc units over other bonds, as shown by a kinetic study of the molar mass distribution of the cleaved Fc-containing and Fc-free reference polymers. The released and oxidized iron ions can be detected with KSCN to generate the red-colored [Fe(SCN)(n)(H2O)(6-n))]((3-n)+) complex or reacted with K-4[Fe(CN)(6)] to afford Prussian blue.