Issue 32, 2013

Solvent effects on the gelation performance of melamine and 2-ethylhexylphosphoric acid mono-2-ethylhexyl ester in water–organic mixtures

Abstract

A two-component gel of melamine (M) and 2-ethylhexylphosphoric acid mono-2-ethylhexyl ester (P) in binary solvent mixtures has been investigated. PM formed opaque gels at a certain water volume fraction in methanolwater mixtures. The minimum gelation concentration (MGC) decreased with increasing the water content, whereas the gel-to-sol transition temperature (Tgel) increased firstly and had a decline at 60% water content. Scanning electron microscopy (SEM) images revealed that the gel fibers formed macroscopic aggregates when an appropriate amount of water was added. When the water content was increased from 25% to 50%, the network in the mixed-solvents became more “uniform” and “denser” and when the water content was increased to 60%, fibers packed more closely together and formed a sheet-like structure. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy patterns (FTIR) of xerogels showed that the gelator had a similar packing mode in the gel state, which was different from the precipitation state. The solvent viscosity had a good correlation with SEM images and gel-to-sol temperature. Hansen solubility parameters and Flory–Huggins parameters were calculated to estimate the gelatorsolvent interaction. The results indicated that gelation occurred when the gelatorsolvent interaction was neither too strong nor too weak, otherwise solution or precipitate was obtained.

Graphical abstract: Solvent effects on the gelation performance of melamine and 2-ethylhexylphosphoric acid mono-2-ethylhexyl ester in water–organic mixtures

Supplementary files

Additions and corrections

Article information

Article type
Paper
Submitted
21 Mar 2013
Accepted
12 Jun 2013
First published
13 Jun 2013

Soft Matter, 2013,9, 7780-7786

Solvent effects on the gelation performance of melamine and 2-ethylhexylphosphoric acid mono-2-ethylhexyl ester in water–organic mixtures

L. Niu, J. Song, J. Li, N. Tao, M. Lu and K. Fan, Soft Matter, 2013, 9, 7780 DOI: 10.1039/C3SM50814E

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