Supramolecular Templation of Entanglements and Their Spectroscopic Detection in Polymer Elastomers

Abstract

Trapped entanglements─topological cross-links among polymer chains in a network─are fundamental to polymers and have been correlated with mechanical properties like toughness, critical for virtually any application of soft materials. Yet, although the concept of polymer entanglement has been around over 80 years, entanglement topology-property relationships remain ill-defined because we lack methods to experimentally install and quantify entanglements with precise topologies. Here, we use supramolecular templates based on phenanthroline-copper(I) complexes to install into poly(methoxyethyl acrylate) elastomer-trapped entanglements whose topology is programmed by the complex geometry. Compared to control materials, we observe 17% diminished swelling and 29% enhanced modulus, with only 0.75 mol % of the entanglement template or 1.5 mol % of the ligand. Moreover, we discovered that fluorescent phenanthroline-based exciplexes formed selectively when entanglement-templating complexes were used, which could in the future enable detection and direct quantification of supramolecular templated entanglements.