Increasingly threaded polypseudorotaxanes with reduced enthalpies of melting

Abstract

Polymers that contain mechanical bonds have unique and useful properties. It is difficult to prepare linear polyrotaxanes that contain well-defined mechanical bonds, which has made it challenging to establish the influence of mechanical bonding on linear polyrotaxane properties. We disclose the synthesis of 1,9-decadiene-pseudorotaxane linear copolymers with variable densities of threaded macrocycles using acyclic diene metathesis (ADMET) polymerization. This enabled our investigation into how macrocyclic threading impacts the thermomechanical properties of linear polypseudorotaxanes. Specifically, we observe that the melting enthalpy decreased from 67 to 5 J g⁻¹ as we increased the molar incorporation of a pseudorotaxane unit. Going forward, we expect ADMET to be a useful strategy to prepare linear mechanically interlocked macromolecules at scales relevant for characterizing their thermomechanical properties.