Related Experiment Video
Updated: Feb 15, 2026

Large Area Substrate-Based Nanofabrication of Controllable and Customizable Gold Nanoparticles Via Capped Dewetting
Published on: February 26, 2019
Entropy-Driven Reversible Agglomeration of Crown Ether Capped Gold Nanoparticles
Alexander P Hill1, Casper Kunstmann-Olsen1, Marcin P Grzelczak1
1Department of Chemistry, University of Liverpool, Liverpool, L7 7ZD, UK.
Abstract:
It is shown that plasmonic gold nanoparticles functionalised with a thiolated 18-crown-6 ligand shell agglomerate spontaneously from aqueous dispersion at elevated temperatures. This process takes place over a narrow temperature range, is accompanied by a colour change from red to purple-blue and is fully reversible. Moreover, the temperature at which it occurs can be adjusted by the degree of complexation of the crown ether moiety with appropriate cations. More complexation leads to higher transition temperatures. The process has been studied by UV/Vis spectroscopy, electron microscopy, dynamic light scattering and zeta potential measurements. A thermodynamic rationale is provided to suggest an entropy-driven endothermic agglomeration process based on attractive hydrophobic interactions of the complexed crowns that are competing against electrostatic repulsion of the charged ligand shells.
Related Concept Videos
Crown Ethers
Entropy Change in Reversible Processes
The statement can be further generalized to prove that entropy is a state function. Take a cyclic process between any two points on a p-V diagram.
Entropy
Entropy
When an ideal gas expands isothermally, the disorder in the gas increases. From the molecular perspective, the gas molecules have more volume to move around in.
Consider an infinitesimal step in the expansion, which...
Standard Entropy Change for a Reaction
Ethers from Alcohols: Alcohol Dehydration and Williamson Ether Synthesis
Ethers can be prepared from organic compounds by various methods. Some of them are discussed below,
Preparation of Ethers by Alcohol Dehydration
In this method, in the presence of protic acids, alcohol dehydrates to produce alkenes and ethers under different conditions. For example, in the presence of sulphuric acid, dehydration of ethanol at 413 K yields ethoxyethane, whereas it yields ethene at 443 K.

