Concern for the environment has been driving major changes in the coatings industry.

We recently described a new approach to surfactant-free latex dispersions prepared by emulsification of a partially neutralized linear acrylic acid-containing styrene-acrylic copolymer without the use of an organic solvent [Polym. Chem. 2017, 8, 2931–2941]. These secondary dispersions consisted of a polymer with a molecular weight (M n = 5000 g mol–1, D̵ = 3) too low to form a useful coating. In the work reported here, we built up the molecular weight of the polymer and introduced partial gel content via a reaction in the dispersed state with a bisepoxide, followed by a reaction with a monoepoxide to reduce the acid number. We monitored the reaction with bisepoxide with T 2-filtered 1H NMR to separate signals of highly mobile small molecules from those of less mobile polymer-bound species. Fluorescence resonance energy transfer measurements were carried out both to monitor polymer exchange among nanoparticles (NPs) as the dispersions in water were annealed and to measure the extent of polymer mixing upon film formation. Our most important finding was that the reaction with the monoepoxide reduced polymer T g and, to a limited extent, promoted polymer interdiffusion during film formation. We also found that the presence of cross-links in the NPs limited the extent of polymer mixing that can be achieved when the polymers were dissolved in a good solvent and cast as a film. The combination of cross-linking and molecular weight build-up strongly reduced the propensity for molecular exchange in the dispersed state.

Multivalency is a key concept in the supramolecular science; it allows an additive or even synergetic enhancement of association constants without the need to replace the basic binding motif. To understand the effects of multivalent binding on the mechanical and dynamic properties of metallo-supramolecular polymer gels, we investigate the concentration-and association strength-dependent linear viscoelasticity of two model systems in the semidilute regime, which are based on either telechelic starpoly(ethylene glycol)s (pEGs) or linear multiblock polyurethanes (PUs) with isolated, monotopic, or adjacent, ditopic terpyridine stickers. In the homogeneous star-pEG gels, the ditopic stickers increase the network strength at identical cross-linker concentrations through the formation of higher functional cross-linking junctions, whereas the mechanical enforcement of the partially clustered PU gels is less-pronounced. The ditopic stickers slow down the dynamics of both gel types to a similar extent by increasing the number of sticker-opening attempts required for network relaxation.

The rational design of transiently crosslinked polymer gels requires a profound understanding of how molecular and topological factors determine the mechanical and dynamic material properties. To refine so-far established structure–property...