6 Cocoon Silk: From Mesoscopic Materials Design …
245
6.1.3 Scope of This Chapter
This chapter attempts to address the following questions: What are the hierarchical
structures constituting SF materials? How do different levels of structures synergistically affect the macroscopic properties? Which techniques can be applied for
structural characterization? This chapter will provide a fundamental, refined description of the hierarchical network structures of SF materials in a bottom-up manner,
which will enable us to comprehensively investigate the above-mentioned topics.
Moreover, the correlation between structure and performance is discussed accordingly. In Sect. 6.2, we present a brief overview of the history of sericulture in China.
In addition, the life cycle of silkworms as well as the silk fabrication process are also
included. In Sect. 6.3, we will first investigate the different levels of the hierarchical
structures of SF materials and discuss how they can be correlated to mechanical
strength. Then, in Sect. 6.4, we will introduce several structural characterization and
imaging technologies. In Sect. 6.5, to illustrate how SF materials are self-assembled,
we will put forward a nucleation-crystal growth model based on comprehensive
observations and detailed experimental verification.
6.2 Silk Road: From Ancient Textiles to Smart Flexible
Functional Materials
6.2.1 History and Life Cycle of Silkworms
The oldest textile fiber, silk, according to Chinese folklore, was first discovered by
Empress His-Ling-Shi (the wife of the mythical Yellow Emperor) in approximately
3000 BC, while she was sipping her tea. The history of sericulture in China is very
long (Fig. 6.3a and b) and is believed to have started during the Chinese Neolithic
period. For instance, the oldest silk found in Henan Province, China, dates to circa
3630 BC. Other examples of very old silk in China are a group of silk threads,
a braided silk belt, and a woven silk cloth fragment excavated from the Liangzhu
culture site in Zhejiang Province, China, all of which date to approximately 2570
BC. Following the discovery of silk, it soon became a valued commodity in ancient
China. With the development of sericulture, silk has become highly prized in China
and throughout the world. For instance, the techniques of silkworm raising and silk
fabrication were spread to nearby countries such as India and Japan (Fig. 6.3c). As
time progressed to 139 BC (the Han dynasty), the ancient Chinese built a trade route
stretching from Eastern China to the Mediterranean Sea called the Silk Road for the
lucrative silk trade (Fig. 6.3d) [21].
In terms of silkworm species, it is generally accepted that silkworms can be
classified into two main categories: mulberry and non-mulberry, based on their diet.
Specifically, the mulberry silkworm refers to B. mori silkworms only. Given that B.
mori silkworms are easily domesticated, they are also called domesticated silkworms.
245
6.1.3 Scope of This Chapter
This chapter attempts to address the following questions: What are the hierarchical
structures constituting SF materials? How do different levels of structures synergistically affect the macroscopic properties? Which techniques can be applied for
structural characterization? This chapter will provide a fundamental, refined description of the hierarchical network structures of SF materials in a bottom-up manner,
which will enable us to comprehensively investigate the above-mentioned topics.
Moreover, the correlation between structure and performance is discussed accordingly. In Sect. 6.2, we present a brief overview of the history of sericulture in China.
In addition, the life cycle of silkworms as well as the silk fabrication process are also
included. In Sect. 6.3, we will first investigate the different levels of the hierarchical
structures of SF materials and discuss how they can be correlated to mechanical
strength. Then, in Sect. 6.4, we will introduce several structural characterization and
imaging technologies. In Sect. 6.5, to illustrate how SF materials are self-assembled,
we will put forward a nucleation-crystal growth model based on comprehensive
observations and detailed experimental verification.
6.2 Silk Road: From Ancient Textiles to Smart Flexible
Functional Materials
6.2.1 History and Life Cycle of Silkworms
The oldest textile fiber, silk, according to Chinese folklore, was first discovered by
Empress His-Ling-Shi (the wife of the mythical Yellow Emperor) in approximately
3000 BC, while she was sipping her tea. The history of sericulture in China is very
long (Fig. 6.3a and b) and is believed to have started during the Chinese Neolithic
period. For instance, the oldest silk found in Henan Province, China, dates to circa
3630 BC. Other examples of very old silk in China are a group of silk threads,
a braided silk belt, and a woven silk cloth fragment excavated from the Liangzhu
culture site in Zhejiang Province, China, all of which date to approximately 2570
BC. Following the discovery of silk, it soon became a valued commodity in ancient
China. With the development of sericulture, silk has become highly prized in China
and throughout the world. For instance, the techniques of silkworm raising and silk
fabrication were spread to nearby countries such as India and Japan (Fig. 6.3c). As
time progressed to 139 BC (the Han dynasty), the ancient Chinese built a trade route
stretching from Eastern China to the Mediterranean Sea called the Silk Road for the
lucrative silk trade (Fig. 6.3d) [21].
In terms of silkworm species, it is generally accepted that silkworms can be
classified into two main categories: mulberry and non-mulberry, based on their diet.
Specifically, the mulberry silkworm refers to B. mori silkworms only. Given that B.
mori silkworms are easily domesticated, they are also called domesticated silkworms.