302
coatings (Zhang and Seeger 2011), cosmetics (Horii and Kannan 2008), foaming
and anti-foaming agents (Baferani et al. 2018), medical implants (Brook 2012),
pharmaceuticals (Rodriguez-Lopez et al. 2019) and sealants. While siloxane polymers have been initially prepared since the second half of the nineteenth century
(1800s), it was not until the mid-1940s that they became industrially and commercially relevant materials. Since then, they have become an important part of our
daily routines in some way or another. Despite this, they are often overlooked as
compared to their carbon-based counterparts.
This chapter highlights many of the fundamental aspects of siloxane polymers
and what gives them such unique functionality. A brief introduction on the silicon
nomenclature is presented to dispel the confusion about the terminology of siloxane
polymers present throughout the chapter. The basic properties and molecular characteristics which differentiate this class of polymer from traditional carbon-based
polymers are also highlighted. A fundamental understanding of these properties better explains the behavior of advanced silicone materials. In addition, we will give an
overview of the main methods in which monomers can be prepared with desired
functional groups and the subsequent polymerization techniques for preparing linear silicone oils. The reactions of functional siloxanes for the preparation of crosslinked materials and elastomers will also be explored.
In the second half of the chapter, recent advances in various applications of
industrial importance will be covered. First, new emerging synthetic techniques for
preparing and reacting siloxanes will be explained. Second, the importance of
silicone- based surfactants in a number of applications will be discussed. Finally,
reactions of siloxanes with inorganic oxide surfaces and other substrates highlighting the siloxane bond as a functional group in its own right will be detailed.
13.2 Silicon Nomenclature
One aspect of siloxane polymers which typically gives people a certain degree of
problems is simply the terminology of the field. With many of the terms appearing
and sounding similar, it is not entirely surprising that many people struggle at the
beginning to find the right use. Figure 13.1A highlights many common siliconcontaining compounds. Of these compounds, silanes are a typical monomer for
siloxane polymers and will be discussed throughout the text. In addition, the terms
siloxanes and silicones are commonly used interchangeably. However, ‘silicone’ is
a more general term for siloxane-containing polymers or siloxane materials, while
siloxane can refer to small molecules, side groups or polymers. An interesting element of the siloxane nomenclature is found in Fig. 13.1B, which does not often
appear outside specific silicone texts. These terms, developed by industrial silicone
chemists at General Electric (Hurd 1946), describe the amount of oxygens in a silicon atom in a material. In this case, a silicon atom with one, two, three or four
oxygen atoms would be referred as a M, D, T or Q unit, respectively. These terms
are useful for preparing the abbreviated nomenclature of compounds and resins. For
K. M. Ryan et al.
coatings (Zhang and Seeger 2011), cosmetics (Horii and Kannan 2008), foaming
and anti-foaming agents (Baferani et al. 2018), medical implants (Brook 2012),
pharmaceuticals (Rodriguez-Lopez et al. 2019) and sealants. While siloxane polymers have been initially prepared since the second half of the nineteenth century
(1800s), it was not until the mid-1940s that they became industrially and commercially relevant materials. Since then, they have become an important part of our
daily routines in some way or another. Despite this, they are often overlooked as
compared to their carbon-based counterparts.
This chapter highlights many of the fundamental aspects of siloxane polymers
and what gives them such unique functionality. A brief introduction on the silicon
nomenclature is presented to dispel the confusion about the terminology of siloxane
polymers present throughout the chapter. The basic properties and molecular characteristics which differentiate this class of polymer from traditional carbon-based
polymers are also highlighted. A fundamental understanding of these properties better explains the behavior of advanced silicone materials. In addition, we will give an
overview of the main methods in which monomers can be prepared with desired
functional groups and the subsequent polymerization techniques for preparing linear silicone oils. The reactions of functional siloxanes for the preparation of crosslinked materials and elastomers will also be explored.
In the second half of the chapter, recent advances in various applications of
industrial importance will be covered. First, new emerging synthetic techniques for
preparing and reacting siloxanes will be explained. Second, the importance of
silicone- based surfactants in a number of applications will be discussed. Finally,
reactions of siloxanes with inorganic oxide surfaces and other substrates highlighting the siloxane bond as a functional group in its own right will be detailed.
13.2 Silicon Nomenclature
One aspect of siloxane polymers which typically gives people a certain degree of
problems is simply the terminology of the field. With many of the terms appearing
and sounding similar, it is not entirely surprising that many people struggle at the
beginning to find the right use. Figure 13.1A highlights many common siliconcontaining compounds. Of these compounds, silanes are a typical monomer for
siloxane polymers and will be discussed throughout the text. In addition, the terms
siloxanes and silicones are commonly used interchangeably. However, ‘silicone’ is
a more general term for siloxane-containing polymers or siloxane materials, while
siloxane can refer to small molecules, side groups or polymers. An interesting element of the siloxane nomenclature is found in Fig. 13.1B, which does not often
appear outside specific silicone texts. These terms, developed by industrial silicone
chemists at General Electric (Hurd 1946), describe the amount of oxygens in a silicon atom in a material. In this case, a silicon atom with one, two, three or four
oxygen atoms would be referred as a M, D, T or Q unit, respectively. These terms
are useful for preparing the abbreviated nomenclature of compounds and resins. For
K. M. Ryan et al.