Chapter 4
Interfacial Gaseous States
4.1 Disjoining Pressure
4.1.1 The Definition
We will see in the next chapter that interfacial gaseous states hold a key to the
nucleation of clathrate hydrates. Nucleation in the real world is almost exclusively
through heterogeneous nucleation for the reasons detailed in Chap. 1. For clathrate
hydrate, since the solubility of a typical guest gas in an aqueous phase is much lower
than the guest gas content in the clathrate form (see Chap. 3), the availability of the
guest gas next to a solid substrate on which heterogeneous nucleation takes place
dictates the heterogeneous nucleation probability of the clathrate hydrate. Thus, the
physical properties of such surfaces hold the key to the heterogeneous nucleation
rates of clathrate hydrates.
An interfacial gaseous state refers to any gaseous phase that metastably exists
next to a solid surface in a liquid phase (Fig. 4.1) [1–4]. An interfacial gaseous state
on a solid substrate in liquid water can readily supply the guest gas to an emerging
nucleus of a clathrate phase and hence would dramatically impact the heterogeneous
nucleation rate of clathrate hydrates.
As we will see later in this chapter, interfacial gaseous states are generally not
thermodynamically stable. Therefore, their presence is transient in nature and they
are destined to disappear sooner or later. Because of this metastability, interfacial
gaseous states are small to begin with and are usually shrinking when they survive
long enough to be detected. Unlike macroscopically large bubbles, the small sizes of
the interfacial gaseous states render their physical states be dominated by the surface
forces exerted by the solid substrate next to them.
The central concept in dealing with such situations is the disjoining pressure.
There are excellent textbooks on the disjoining pressure, such as by Derjaguin et al.
[5] and by de Gennes et al. [6], so here we only cover the essence of the disjoining
pressure that is necessary for an understanding of interfacial gaseous states. For
© Springer Nature Switzerland AG 2020
N. Maeda, Nucleation of Gas Hydrates,
https://doi.org/10.1007/978-3-030-51874-5_4
83
Interfacial Gaseous States
4.1 Disjoining Pressure
4.1.1 The Definition
We will see in the next chapter that interfacial gaseous states hold a key to the
nucleation of clathrate hydrates. Nucleation in the real world is almost exclusively
through heterogeneous nucleation for the reasons detailed in Chap. 1. For clathrate
hydrate, since the solubility of a typical guest gas in an aqueous phase is much lower
than the guest gas content in the clathrate form (see Chap. 3), the availability of the
guest gas next to a solid substrate on which heterogeneous nucleation takes place
dictates the heterogeneous nucleation probability of the clathrate hydrate. Thus, the
physical properties of such surfaces hold the key to the heterogeneous nucleation
rates of clathrate hydrates.
An interfacial gaseous state refers to any gaseous phase that metastably exists
next to a solid surface in a liquid phase (Fig. 4.1) [1–4]. An interfacial gaseous state
on a solid substrate in liquid water can readily supply the guest gas to an emerging
nucleus of a clathrate phase and hence would dramatically impact the heterogeneous
nucleation rate of clathrate hydrates.
As we will see later in this chapter, interfacial gaseous states are generally not
thermodynamically stable. Therefore, their presence is transient in nature and they
are destined to disappear sooner or later. Because of this metastability, interfacial
gaseous states are small to begin with and are usually shrinking when they survive
long enough to be detected. Unlike macroscopically large bubbles, the small sizes of
the interfacial gaseous states render their physical states be dominated by the surface
forces exerted by the solid substrate next to them.
The central concept in dealing with such situations is the disjoining pressure.
There are excellent textbooks on the disjoining pressure, such as by Derjaguin et al.
[5] and by de Gennes et al. [6], so here we only cover the essence of the disjoining
pressure that is necessary for an understanding of interfacial gaseous states. For
© Springer Nature Switzerland AG 2020
N. Maeda, Nucleation of Gas Hydrates,
https://doi.org/10.1007/978-3-030-51874-5_4
83