Supramolecular hydrogels based on 1,3,5‐benzene tricarboxamides
type: CreativeWork
description: In this thesis the pH-sensitive aggregation behavior of low molecular weight (lmw) compounds based on the 1,3,5-benzene tricarboxamide (BTA) self-assembly motif is investigated in aqueous systems to elucidate their potential to form supramolecular hydrogels. The thesis covers four main subjects: i) the self-assembly behavior of pH-sensitive BTAs in aqueous systems is investigated with regard to their ability to form nano-fiber networks and supramolecular hydrogels; ii) the formation of supramolecular chromophores during gelation is studied using spectroscopic methods; iii) the possible application of the hydrogel as an adsorption material for small dye molecules and the controlled delivery is elucidated; and iv) the formation of controlled hydrogel films on conductive substrates via electrogelation is investigated. Five different BTA derivates were synthesized to show that a sensitive balance between lipophilic and hydrophilic interactions must be fulfilled to enable pH-sensitive aggregation in water. Besides the hydrophobic shielding of the BTA core, the introduction of three carboxylic acid groups as lateral headgroups proved to be mandatory to achieve stable gel formation upon change of the pH value. Different gelation methods were investigated for the carboxylic acid derivative and the properties of the resulting hydrogels were compared. Upon addition of aqueous acid solutions only inhomogeneous gels can be obtained. The diffusion of hydrochloric acid gas leads to macroscopically homogenous hydrogels with a gradient in mechanical stability. The addition of glucono-delta-lactone (GdL), a slow proton donating agent, enables the formation of stable homogenous gels with a homogeneous mechanical stability. Gels prepared with hydrochloric acid gas or GdL have a very low critical gelation concentration (cgc) of 2 g L 1. Even at this low gelator concentrations the gels are thermally stable up to the boiling point of water. They are also stable in various organic solvent…
abstract: In this thesis the pH-sensitive aggregation behavior of low molecular weight (lmw) compounds based on the 1,3,5-benzene tricarboxamide (BTA) self-assembly motif is investigated in aqueous systems to elucidate their potential to form supramolecular hydrogels. The thesis covers four main subjects: i) the self-assembly behavior of pH-sensitive BTAs in aqueous systems is investigated with regard to their ability to form nano-fiber networks and supramolecular hydrogels; ii) the formation of supramolecular chromophores during gelation is studied using spectroscopic methods; iii) the possible application of the hydrogel as an adsorption material for small dye molecules and the controlled delivery is elucidated; and iv) the formation of controlled hydrogel films on conductive substrates via electrogelation is investigated. Five different BTA derivates were synthesized to show that a sensitive balance between lipophilic and hydrophilic interactions must be fulfilled to enable pH-sensitive aggregation in water. Besides the hydrophobic shielding of the BTA core, the introduction of three carboxylic acid groups as lateral headgroups proved to be mandatory to achieve stable gel formation upon change of the pH value. Different gelation methods were investigated for the carboxylic acid derivative and the properties of the resulting hydrogels were compared. Upon addition of aqueous acid solutions only inhomogeneous gels can be obtained. The diffusion of hydrochloric acid gas leads to macroscopically homogenous hydrogels with a gradient in mechanical stability. The addition of glucono-delta-lactone (GdL), a slow proton donating agent, enables the formation of stable homogenous gels with a homogeneous mechanical stability. Gels prepared with hydrochloric acid gas or GdL have a very low critical gelation concentration (cgc) of 2 g L 1. Even at this low gelator concentrations the gels are thermally stable up to the boiling point of water. They are also stable in various organic solvent…
author: Behr, Marina
date published: 2015-04-27
date modified: 2026-07-27T18:49:49Z
provider: Universität Bayreuth
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Universität Bayreuth