This talk will examine physico-chemical aspects of self-repairing processes in thermoplastic and thermosetting polymers.To achieve self-healing behavior in thermosets,stability and reactivity of reforming bonds resulting from physical chain slippage and/or chemical bond cleavage must be synchronized with entropically driven chain rearrangements.While covalent incorporation of photochromic monomers into networks facilitates color changes during damage,our recent studies also showed that chemically modified thermosetting polyurethanes are capable of self-repairs under atmospheric amounts of CO2 and H2O,thus resembling plants behavior during photosynthesis.