Insights into the Kinetics of Supramolecular Comonomer Incorporation in Water

Abstract

Multicomponent supramolecular polymers are a versatile platform to prepare functional architectures, but a few studies have been devoted to investigate their noncovalent synthesis. Here, we study supramolecular copolymerizations by examining the mechanism and time scales associated with the incorporation of new monomers in benzene-1,3,5-tricarboxamide (BTA)-based supramolecular polymers. The BTA molecules in this study all contain three tetra(ethylene glycol) chains at the periphery for water solubility but differ in their alkyl chains that feature either 10, 12 or 13 methylene units. C10BTA does not form ordered supramolecular assemblies, whereas C12BTA and C13BTA both form high aspect ratio supramolecular polymers. First, we illustrate that C10BTA can mix into the supramolecular polymers based on either C12BTA or C13BTA by comparing the temperature response of the equilibrated mixtures to the temperature response of the individual components in water. Subsequently, we mix C10BTA with the polymers and follow the copolymerization over time with UV spectroscopy and hydrogen/deuterium exchange mass spectrometry experiments. Interestingly, the time scales obtained in both experiments reveal significant differences in the rates of copolymerization. Coarse-grained simulations are used to study the incorporation pathway and kinetics of the C10BTA monomers into the different polymers. The results demonstrate that the kinetic stability of the host supramolecular polymer controls the rate at which new monomers can enter the existing supramolecular polymers.

Supramolecular Double Helices from Small C3-Symmetrical Molecules Aggregated in Water

“… 39 After both molecules were mixed, the same heating–cooling protocol was used to be consistent with the sample preparation of the homopolymers (see Supporting Information ). During this protocol the molecules are heated to 80 °C, which is above their cloud point temperature, 53 and this is likely causing a temporal dehydration of the ethylene glycol and glycerol units. Similar to above, cryo-TEM micrographs of the respective copolymer samples were recorded and these were subsequently analyzed by MSA and classification techniques.…”

The Martini Model in Materials Science

“…An important example are 1,3,5‐benzenetricarboxamide (BTA)‐based supramolecular polymers, synthetic supramolecular materials which have been studied in detail by Bochicchio, Pavan, and co‐workers. [ 257–263 ] Two Martini models for the BTA core were developed, both capturing the step‐wise cooperative polymerization mechanism which leads to the formation of supramolecular fibers ( Figure ) [ 257 ] : BTA monomers initially aggregate quickly in water due to hydrophobic interactions; the disordered aggregates formed then reorganize into directional oligomers on a slower time scale; such ordered oligomers then fuse to form and elongate the supramolecular fiber on an even slower time scale. In the more refined model, additional charged particles were introduced to improve the stacking interactions between the BTA cores, [ 257 ] similarly to the ones introduced within amino acid side chains by de Jong et al.…”

“…[ 257 ] A Dry Martini [ 59 ] version of the BTA model has also been put forward by the same authors. [ 259 ] There are several applications of structural variants of the BTA supramolecular polymer, [ 258,260–262 ] some in combination with enhanced sampling and machine‐learning techniques. [ 258,262 ] For example, Martini‐based well‐tempered metadynamics simulations were used to investigate monomer exchange in and out of the fibers, finding a central role of defects on the supramolecular structure in this process.…”

Dynamics in supramolecular nanomaterials

“…HDX also enables the tracking of exchange of different types of monomers in multicomponent systems [86][87] . This capability is achieved by employing mass spectrometry to distinguish between molecular masses.…”