Inorganic Polymers : Silicates/ Silicones



Inorganic Polymers : Silicates/ Silicones

The polymers whose backbone chains are made of carbon atoms, is called organic polymers. But there are some other kinds of polymers whose back bone is not made of carbon atoms but consist of atoms other than carbon. These arc called inorganic polymers.

Silicones are synthetic polymers made from the products of nature. Although “silicone” is often used as a generic term for nearly all substances that contain a silicon atom, it is more properly described as an entirely synthetic polymer containing a Si-0 backbone. To this backbone, organic groups are frequently attached to the silicon atoms via a Si-C bond.

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This general description defines the broad class of polymers known as silicones. The most common example is poly (dimethylsiloxane) or PDMS. This polymer has a repeating (CH3)2SiO unit. These materials are the basic building blocks of the silicone industry. Depending upon the number of repeat units in the polymer chain and the degree of cross-linking at least six classes of commercially important products such as fluids, emulsions, compounds, lubricants and resins can be produced.

HISTORY

F.S.Kipping’s systematic study of the organosilicon compounds gave the way for the development of the silicone industry. He synthesized dialkyldichlorosilanes from SiCl4 and Grignard reagents, which could be rapidly hydrolyzed to the corresponding dihydroxy derivatives.

Gem-diols, >C(OH)2, being unstable can decompose eliminating a molecule of water and give ketones. Kipping expected a similar behaviour from these compounds and hence named them silicones. However, instead of the expected ketones, the reaction resulted in only oily liquids and resins, which were recognised as long-chain polymers arising from intermolecular condensations.

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