How to Characterize Supramolecular Polymers: A User Guide

Unlike traditional macromolecules, supramolecular polymers are assemblies composed of individual monomeric units that are connected not by covalent bonds but through reversible, noncovalent interactions. This fundamental distinction from conventional polymers endows them with a wide range of novel and tunable properties, such as intrinsic dynamic reversibility, responsiveness to external stimuli (e.g., temperature, pH, light, and chemical environment), self-healing capability, and the ability to undergo controllable disassembly and reassembly. However, standardized or universally applicable techniques for the comprehensive characterization of supramolecular polymers have not been fully established yet. To address this gap, this review provides a detailed and systematic summary of various methodologies currently employed to characterize supramolecular polymers, including nuclear magnetic resonance spectroscopies (VC-NMR, VT-NMR, COSY, NOESY, ROESY, DOSY NMRs), mass spectrometries (ESI, MALDI, APCI), photo spectroscopies (UV-vis, FL, CD, IR, et al.), light scattering methods (DLS, SLS), X-ray techniques (SC-XRD, SAXS, WAXS, et al.), microscopies (AFM, SEM, TEM, CLSM, et al.) and methods used in traditional polymers (SEC, VPO, TGA, DSC, et al.). Due to the complexity and multifaceted nature of supramolecular systems, no single technique is capable of providing a complete and unambiguous description. Therefore, a combination of complementary techniques is typically required to achieve a thorough insight into their thermodynamics, kinetics, morphology, and responsiveness.