Published: June 15, 2018
Joshua A. Hammons, Fan Zhang, Jan Ilavsky
Many applications of deep eutectic solvents (DES) rely on exploitation of their unique yet complex liquid structures at the mesoscopic level. Due to the ionic nature of the DES components, their diffuse structures are known to be affected in the presence of charged surface, similar to other room temperature ionic liquids. The degree of perturbation near curved, charged surfaces with mesoscopic dimensions, however, remains unexplored experimentally. We performed in situ, synchrotron-based ultra-small angle X-ray scattering (USAXS) experiments to study the solvent distribution near the surface of charged mesoporous silica particles (MPS) (≈ 0.5 µm in diameter) suspended in both water and a common type of DES (1:2 choline Cl-:ethylene glycol). A careful USAXS analysis reveals that the perturbation of electron density distribution of DES extends ≈ 1 μm beyond the particle surface, and that this perturbation can be manipulated by the addition of salt ions (AgCl). Our results also demonstrate that the composition of the pore-filling fluid in the nano-scale pores of the MPS strongly depends on the type of solvents and availability of salt ions. Notably, we extracted the real-space structures of these fluctuations from the USAXS data using a simulated annealing approach. The heuristic analytical approach established in this paper does not require a priori knowledge about the scattering form factor, and can be generalized to a wide range of complex small-angle scattering problems that cannot be easily resolved using traditional analysis methods.
Citation: Journal of Colloid and Interface Science
Pub Type: Journals
Electrostatic stabilization, deep eutectic solvents, pore activity, nanoparticle stabilization, small angle scattering, mesoporous silica, drug delivery, green technology
Created June 15, 2018, Updated November 10, 2018