An Introduction to Silicone

In our last blog we have introduced some basic chemical characteristics & applications of silicone and its broadly extensions- silicone oils & LSR silicone rubbers.

Today, we will introduce more about the nature and the history of silicone element rather than just one specific silicone product which is developed from it.

(silicone oils and silicone rubbers-liquid form)

What is Silicone?

Silicone is a chemical element which could be seen in everyday life easily; the name is originated from Latin word “silex”. Its symbol is Si and its atomic number is 14. The amount of storage of silicone is 25.7% in the earth curst and which is only lower than oxygen (which is 49.4%). It is thus the second richest element.

Silicone has both of physical & chemical characteristics between metalloids’ and non-metals’. It is because its ranking in the periodic table of the elements- it is in the same row as carbon and germanium and the position is just between these two elements (shown as the picture below). Sometimes silicone is considered as a semi-metalloid.

A Periodic Table of Elements

(cited from: https://pubchem.ncbi.nlm.nih.gov/periodic-table/)

As mentioned before, the chemical characteristics are pretty similar with carbon. However, many are also different. For example, carbons are usually combines with many other elements and then become organic matters at last. However, silicone usually combines with other elements to become inorganic minerals such as silicone oxide, silicates and many others. Besides these, there are also few compounds of silicone in atmosphere, rain waters, sea waters and many animals.

In normal atmospheric temperature, the element silicone usually exists in the form of amorphous or crystalline solids. Silicone only has one crystalline form in normal atmospheric temperature and normal pressure. It has diamond crystal structure whose silicone atoms are mutually paralleled and spread averagely in its space. The distance between any closed two silicones atoms are also the same. The crystal form silicone is usually dark blue with flash metallic luster. What is more, it is due to the atomic crystal nature, the crystal silicone is pretty hard but crispy.

Silicone is very stable in normal atmospheric. However, its chemical characteristics will be very active once in high temperature. It could be reacted with oxygen or even nitrogen in the air to produce corresponding oxides or nitride. Its chemical characteristics increase with the decrease of its crystallinity. Melting silicone can corrode almost all daily temperature-resistance materials.

The applications of element silicone are very wide. From electronic industries to chemical raw materials, from textile industries to cosmetics, silicone could be easily find to play an important role.

The Founding Period of Organic Silicone Industry

The history of using silicone and its compounds is of thousands of years. In the classic era or even in the periods which are way earlier, humans used the almost countless natural silicates and silica for their daily life and work. It is after the development of different industries, products like concretes, glasses and ceramics are all founded with the effective use of silicone raw materials. It is especially thankful to the successful & rapid construction of organic chemistry (which is mainly about studying the element of carbons), the relevant silicone chemistry has also been mentioned after the carbon has a collection of mature research results & industrial applications. The early-stage academic purpose of silicone chemistry is to expect new materials which have stable chemical characteristics which carbons are proved to have already. Later on, the scientists make a further goal which is to find silicone-carbon combined chemistry.

In 1863, the French scientist C. Friedel and J. M. Crafts got SiEt4 which is the first known chemical that has a Si-C key. The chemical is based on SiCl4 and ZnEt2 which were reacted together in a sealed tube with a temperature of 160℃.

In 1872, A Ladenburg made a similar experiment which is to use ZnEt2 to react with Si(OEt3)Cl and Na. 1n 1874, he also used HgPh2 and SiCl4 to get PhSiCl3 in the sealed tube. Both of the two experiments got successful results.

From 1863 to 1903, many scientists tried their best to get achievement and progresses in organic silicone industry and this period is also considered as the founding period of organic silicone chemistry.

Another famous chemist is F. S. Kipping who is British. He spent more than 40 years in studying organic silicone chemistry and made many foundations to today’s silicone organic chemistry.

In the end of 30s of 20^th century, the research purposes gradually shift to find the industrial & practical applications of silicones due to the gradually matured theory of getting silicone compounds. Some scientists from the U.S.A and the former U.S.S.R have realized the bright future of silicone products’ applications. They started to explore more on silicone polymers. After finding the existence of silicone resins, they got the basic form of today’s silicone oil successfully. In 1941, more effective way to produce silicone products came up one by one. The efficiency to produce silicone chemicals was also rapidly increasing. In 1943, two famous American companies- Dow and Corning invested together to form a new company Dow Corning (or abbreviation DC). In 1947, General Electric organized the department of organic silicones with the new silicone manufacturing methods and its following new factories also use these methods. During the whole 40s of 20^th century, DC and GE have developed a variety of new chemicals based on silicones. Not only in the U.S.A, the former U.S.S.R also developed new organic silicone manufacturing devices during the period.

Silicone Industries in the Post World War Period

It is after the Second World War, organic silicone products (like silicone liquid oils) are proved to be effective in military-grade products. This leads many governments to pay more attentions to organic silicone chemistry. In the 50s of 20^th century, many today’s famous companies like Wacker and Bayer from Germany, R-P from France, ICI from Britain and many other companies were going to build new organic silicone manufacturing devices. It is due to the mass escalations, the prices and the manufacturing cost of organic silicone were dropped rapidly and the new varieties of silicone chemicals came out more and more frequently.

During 1938 and 1965, organic silicone chemistry has made a striking breach in reactions and the corresponding mechanisms. As for the silicone polymers, a new set of basic technologies was developed and still been used in today’s silicone manufacturing process. This period is called the developing period of organic silicone chemistry.

After 1965, many countries turned to develop the civil industrial uses of silicone products. Medical and electronic industries are two evident examples of these developments. Pharmaceutical industry also benefits a lot from the applications of silicone products in several medicines (like our silicone oils use for Aciclovir).

Today’s Silicone Industries

The silicone products like dmethyl fluids are not widely been known for ordinaries until the recent days. Even in the beginning of the 21^st century, many people who do not involve in chemical or relevant manufacturing industries know little about silicones. However, it is since more requirements on green environment and new materials. Silicone products become more public to the audiences even they have never been related to science or chemistry closely.

In the foreseeable near future, silicone and its extensions like silicone liquid rubbers, will be one of the hottest materials and topics in the world.