A spotlight on the interactions governing gelation behavior in water: a combined experimental and computational study of a bis-urea based hydrogel

Scriptie/Masterproef: Master's Thesis

Samenvatting

Gels have been around for centuries. However, it is not until recently that a specific class of gels, low molecular weight gels, gained significant attention amongst scholars. This is due to their potential in many high tech applications such as tissue engineering, drug delivery, waste removal and so on. Unfortunately, their discovery is serendipitous, which makes the design of these materials problematic.
Gels typically consist of two substances: a fluid and a gelator. The latter forms a network that immobilises the fluid leading to the extraordinary features of a gel. The inability to predict gelation is often assigned to the inaccurate description of the interactions between these gelator molecules. Therefore, this work aimed to rationalise the gelation behaviour by gaining insight into the crucial interactions. To achieve this, a unique combination of experiments and computational calculations was used on a set of bis-urea based low molecular weight hydrogelators.
A library of compounds was synthesised. To assess their gelation performance, vial inversion tests and rheology measurements were performed. From this, three efficient new low molecular weight hydrogelators were discovered. Moreover, it was also observed that the type of gelation procedure significantly affected their performance.
Additionally, a set of computational calculations was performed on different scales, which ultimately formed a bottom-up approach. This method identified the importance of two non-covalent hydrogen bonding interactions, hydrogen bonding between two urea moieties and hydrogen bonding between a urea moiety and a pyridine ring. Remarkably these interactions appeared intra- as well as intermolecular.
With these results, the gelation performance of the studied compounds was partially rationalised. As such, this study is a first step towards a smarter design of low molecular weight gelators.
Datum prijs2 jul 2018
Originele taalEnglish
SponsorenKU Leuven
BegeleiderMercedes Alonso Giner (Promotor), Frank De Proft (Promotor) & Wim De Borggraeve (Promotor)

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