Supramolecular hydrogels that are formed from low molecular weight gelators are a new class of soft materials which are gaining prominence. Depending on their molecular make up, these soft gel materials are formed based on different triggers, pH being one among them. In order to build applications with pH-triggered supramolecular gelators, it is necessary to understand their structure-property relationships and learn how to predict, control material properties. As explained in chapter 1, this thesis dealt with the above topics via three distinct fronts: Gelation kinetics, predictive modelling and electrochemical patterning....@en

This study investigates the stabilization of oil/water emulsions as a function of addition of a biopolymer (scleroglucan) which acts as an emulsion stabilizer. Rheological characterization in the form of controlled stress creep measurements has been carried out and it reveals the colloidal gel exhibiting a delayed yielding in a certain applied stress window. The delay time and stresses that an emulsion can withstand depend strongly on the concentration of added scleroglucan. Increasing polymer concentration, however, is limited to a maximum value, above which a limited effect on the delay time is observed. Investigating of the emulsion under study was visualized by means of cryo transmission electron microscopy which shows adsorption of scleroglucan onto the surface of the oil particles and a gel-like structure that connects the oil phases. The results mentioned in this study support that scleroglucan-surfactant interactions play a key role in the stabilization of the oil/water emulsion.@en

The work presented here shows that the growth of supramolecular hydrogel fibers can be spatially directed at the nanoscale by catalytic negatively charged nanoparticles (NCNPs). The NCNPs with surfaces grafted with negatively charged polymer chains create a local proton gradient that facilitates an acid-catalyzed formation of hydrogelators in the vicinity of NCNPs, ultimately leading to the selective formation of gel fibers around NCNPs. The presence of NCNPs has a dominant effect on the properties of the resulting gels, including gelation time, mechanical properties, and network morphology. Interestingly, local fiber formation can selectively entrap and precipitate out NCNPs from a mixture of different nanoparticles. These findings show a new possibility to use directed molecular self-assembly to selectively trap target nano-objects, which may find applications in therapy, such as virus infection prevention, or engineering applications, like water treatment and nanoparticle separation.

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While the formation of (tri)block copolymer hydrogels has been extensively investigated, such studies mostly focused on equilibrium self-assembling whereas the use of preformed structures as building blocks such as out of equilibrium, quenched, nanofibrillar micelles is still a challenge. Here, we demonstrate that quenched, ultralong polystyrene-b-poly(ethylene oxide) (PS-b-PEO) micelles can be used as robust precursors of hydrogels. Two cross-linking strategies, (i) thermal fusion of micellar cores and (ii) chemical cross-linking of preformed micellar coronas were studied. The gelation process and the structure of the micellar networks were investigated by in situ rheological measurements, confocal microscopy and transmission electron microscopy. Direct observation of core fusion of preformed quenched micelles is provided validating this method as a robust gelation route. Using time sweep rheological experiments, it was found for both cross-linking methods that these 3D "mikado" gels are formed in three different stages, containing (1) initiation, (2) transition (growth), and (3) stabilization regimes.@en