Mechano-responsive composition

A two-part mechano-responsive composition, comprising:

• Part I:
• a tetra-glycidyl amine multifunctional epoxy resin represented by the general formula (I);
• wherein R1 represents a linear or branched, unsubstituted or substituted alkylene group having 1 to 10 carbon atoms;
• and
• R2, R3, R4 and R5, independently each other, represent a direct bond, a linear or branched, unsubstituted or substituted alkylene group having 1 to 10 carbon atoms, an unsubstituted or substituted arylene group having 6 to 20 carbon atoms, or a combination of the alkylene and the arylene;
• and
• Part II:
• consisting of a polythiol and a tertiary amine catalyst;
• wherein more than 50% of the polythiol carries at least 3 thiol groups per molecule and when cured and subjected to mechanical stimuli, the cured composition changes color.