Supramolecular polymers are aggregates of monomers that self-assemble through non-covalent interactions. Due to their dynamic and responsive behavior and their tunability supramolecular polymers have many applications. We study 1,3,5-bezenetricarboxamide (BTA) polymers which are used as biocompatible agents for drug delivery, MRI contrast reagents and as organogels and hydrogels.

Using correlative single-molecule fluorescence and atomic force microscopy (AFM) we studied the structure and mechanical properties of BTA polymers. Correlating AFM to fluorescence microscopy allows us to couple nanoscale morphological information to microscale far-field optical images. A fraction of polymers was found to be clustered or entangled due to inter- and intrachain interactions. Persistence length analysis revealed that clustered and entangled polymers exhibit a significantly longer persistence length that is more broadly distributed compared to single unentangled polymers. We compare the measured heterogeneity in the persistence length to numerical simulations. This comparison reveals that the experimental data exhibits significantly more heterogeneity, which is attributed to polymer-substrate interactions and structural diversity within the polymer.