The dilute solution properties of maleic anhydride and maleic acid copolymers. II-unperturbed dimensions and persistence lengths of chains in solution

Hybrid Nanocrystals of Small Molecules and Chemically Disordered Polymers

Organic crystals formed by small molecules can be highly functional but are often brittle or insoluble structures with limited possibilities for use or processing from a liquid phase. A possible solution is the nanoscale integration of polymers into organic crystals without sacrificing long-range order and therefore function. This enables the organic crystals to benefit from the advantageous mechanical and chemical properties of the polymeric component. We report here on a strategy in which small molecules cocrystallize with side chains of chemically disordered polymers to create hybrid nanostructures containing a highly ordered lattice. Synchrotron X-ray scattering, absorption spectroscopy, and coarse-grained molecular dynamics simulations reveal that the polymer backbones form an "exo-crystalline" layer of disordered chains that wrap around the nanostructures, becoming a handle for interesting properties. The morphology of this "hybrid bonding polymer" nanostructure is dictated by the competition between the polymers' entropy and the enthalpy of the lattice allowing for control over the aspect ratio of the nanocrystal by changing the degree of polymer integration. We observed that nanostructures with an exo-crystalline layer of polymer exhibit enhanced fracture strength, self-healing capacity, and dispersion in water, which benefits their use as light-harvesting assemblies in photocatalysis. Guided by computation, future work could further explore these hybrid nanostructures as components for functional materials.

Universal binding behavior for ionic alkyl surfactants with oppositely charged polyelectrolytes

Oppositely charged polyelectrolyte-surfactant mixtures are ubiquitous in biology and the basis of numerous consumer healthcare products. Despite their broad use, however, a rational approach to their formulation remains challenging because of the complicated association mechanisms. Through compilation and analysis of literature reports and our own research, we have developed a semiempirical correlation of the binding strength of surfactants to polyelectrolytes in salt-free mixtures as a function of the polyion linear charge density and the surfactant hydrophobicity. We have found that the cooperative binding strength increases as the square of the polyelectrolyte's linear charge density and in proportion to the surfactant's hydrophobicity, such that a quantitative relationship holds across a broad range of polyelectrolytes. Deviations from the correlation reveal the role of system-specific interactions not considered in the analysis. This engineering relationship aids in the rational design of oppositely charged polyelectrolyte-surfactant formulations for consumer products and biomedicines by enabling the prediction of binding strengths in polyelectrolyte-surfactant mixtures based on mesoscale parameters determined from the chemical composition.