Chapter 1
Introduction
Abstract A brief introduction of gels, their components, driving force and characterization is given in this chapter.
Keywords Gels Á Supramolecular interactions Á Characterization
A gel is “a soft, solid or solid-like material consisting of two or more components
one of which is a liquid, present in substantial quantity” according to Kramer’s
definition [1–3]. Gels often consist of two continuous phases which interpenetrate
on the macroscopic scale. Gels consist mainly of a liquid (e.g. water, alcohol) which
interpenetrates with a persistent network structure, formed by a second species, the
gelator. Solvent is the major component, up to about 99% by weight of the gel,
while the remaining 1% is the gelator [4]. The persistent gelator network prevents
the liquid constituent from flowing freely due to its attraction to the liquid, although
the molecules of the liquid continue to diffuse throughout the structure. Therefore,
gels exhibit some rheological properties like those of a solid.
1.1 Components of Gels
Gelators may be discrete small molecules, polymers, inorganic particles or colloidal
particles (Fig. 1.1). The gelators aggregate via various supramolecular interactions
to form one-dimensional (1D), 2D and 3D structures. For discrete small molecules,
1D structures (e.g. fibres) may be formed via intermolecular–supramolecular
interactions such as hydrogen bonding, p…p stacking, van der Waals attraction,
solvophobic effects, forming supramolecular gels. When polymer chains are
cross-linked via various interactions, polymer gels may be obtained. In inorganic
gels, precursors react to form inorganic colloidal particles and the particles are
further cross-linked to form inorganic gel matrix. When bridging molecular
Jianyong Zhang and Yongguang Li contributed together to this chapter.
© Springer Nature Singapore Pte Ltd. 2018
J. Zhang et al., Gel Chemistry, Lecture Notes in Chemistry 96,
https://doi.org/10.1007/978-981-10-6881-2_1
1
Introduction
Abstract A brief introduction of gels, their components, driving force and characterization is given in this chapter.
Keywords Gels Á Supramolecular interactions Á Characterization
A gel is “a soft, solid or solid-like material consisting of two or more components
one of which is a liquid, present in substantial quantity” according to Kramer’s
definition [1–3]. Gels often consist of two continuous phases which interpenetrate
on the macroscopic scale. Gels consist mainly of a liquid (e.g. water, alcohol) which
interpenetrates with a persistent network structure, formed by a second species, the
gelator. Solvent is the major component, up to about 99% by weight of the gel,
while the remaining 1% is the gelator [4]. The persistent gelator network prevents
the liquid constituent from flowing freely due to its attraction to the liquid, although
the molecules of the liquid continue to diffuse throughout the structure. Therefore,
gels exhibit some rheological properties like those of a solid.
1.1 Components of Gels
Gelators may be discrete small molecules, polymers, inorganic particles or colloidal
particles (Fig. 1.1). The gelators aggregate via various supramolecular interactions
to form one-dimensional (1D), 2D and 3D structures. For discrete small molecules,
1D structures (e.g. fibres) may be formed via intermolecular–supramolecular
interactions such as hydrogen bonding, p…p stacking, van der Waals attraction,
solvophobic effects, forming supramolecular gels. When polymer chains are
cross-linked via various interactions, polymer gels may be obtained. In inorganic
gels, precursors react to form inorganic colloidal particles and the particles are
further cross-linked to form inorganic gel matrix. When bridging molecular
Jianyong Zhang and Yongguang Li contributed together to this chapter.
© Springer Nature Singapore Pte Ltd. 2018
J. Zhang et al., Gel Chemistry, Lecture Notes in Chemistry 96,
https://doi.org/10.1007/978-981-10-6881-2_1
1