Covalent
macromolecules tend to fragment under mechanical stress
through the mechanochemical scission of covalent bonds in the backbone.
However, linear polymers that have been intramolecularly collapsed
by covalent bonds show greater mechanochemical stability compared
to other thermoplastics. Here, rhodium-π bonds are used for
intramolecular collapse in order to show that mechanical stress can
be removed from the polymer backbone and focused on weaker intramolecular
cross-links, leading to polymer unfolding instead of mechanochemical
events at the backbone. Moreover, given rhodium-π bonds form
spontaneously, by changing the time interval between ultrasound pulses,
we demonstrate that entropic spring effects can lead to polymer refolding
and reformation of the previously cleaved metal–ligand bonds,
effectively repairing the intramolecular noncovalent cross-links.
These findings provide the first example of an intramolecular repairing
mechanism in synthetic molecules in solution, allowing for restoration
of chemical bonds after mechanochemical events.
Oxazolines containing carbomethoxy‐, acetoxy‐, and hydroxy‐alkyl groups on the side chain were prepared and polymerized. The properties of the polymers were investigated.
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