silicones has wide range variety of applications.it has many properties which is used to synthesize many materials that can be commercialized.

1. Silicones and
Silicones in Technology
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2. Introduction
• Polymers in which the main chain consists of repeating -Si-O- units
with organic side groups are referred to as polyorganosiloxanes or
as silicones.
• The silicones are a group of organosilicon polymers.
• The most common example is poly-dimethylsiloxane or PDMS.
• This synthetic polymer has a repeating [(CH3)2SiO] unit.
• This is the basic building block of silicones
• They have unique properties due to the presence of organic groups
attached to a chain.
• They have a wide variety of commercial uses. 2

3. History
• 1904 - Frederic Stanley Kipping was the
first to achieve extensive synthesis of
silicone compounds and coined the name
‘silicones’. He is considered to be the
‘founder’ of silicone science.
• 1931- James Franklin Hyde
carries out the first successful
research leading to commercial
production of silicones.
3https://www.onthisday.com/people/j-franklin-hydehttp://charlesduval.org/frederic_stanley_kipping

4. Synthesizing silicones
• 1940 - Richard Gustav Müller and Eugene George Rochow develop, a
direct method for synthesizing silicones on an industrial scale.
https://www.ua.tu-dresdef_CD.asp?Code=Chemie&ID=656n.de/Detail_pro http://www.chemheritage.org/discover/collections/oral-histories/details/rochow-eugene-g.aspx
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R.G.Muller E.G.Rochow

5. Moon Landing
• 1969 - The first imprint that Neil Armstrong left on lunar soil
was made with a silicone rubber boot sole. In addition, new
silicone materials used in the lunar for the crew’s safety and
support systems.
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6. Computer technology
• 1980's - Silicones played an integral role in advancements in
computer technology, telecommunications and all other related
fields that rely on the microchip.
• Without silicone to protect products from extreme temperatures
and contamination, we would not have many of the
technological and electronic innovations we take for granted
today.
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7. Preparation and Properties Of
Silicones
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8. Silicone nomenclature
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9. Synthesis of Silicones
• The production of silicones from silicon takes place in three
stages:
Synthesis of chlorosilanes
Hydrolysis of chlorosilanes
Condensation of silanols
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General formula:RnSiX4-n
Keith Purcell ,Koltz,Inorganic chemistry

10. Preparation of Silicones
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250-280°C
Cu
•Silicones are commercially
produced from silicon and
methyl chloride in a process
known as the "direct
reaction" or the "Rochow-
Muller direct process."

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12. 12http://www.silicones.eu/what-are-silicones/silicones-production

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14. Important differences between silicon
and carbon
Silicon Carbon
Size Larger than C Comparatively smaller than Si
electronegativity Lesser than C (1.8) Comparatively higher than
Si(2.5)
Bond distance and angle
(X-O) (X=Si,C)
Larger than C Comparatively smaller than Si
Forms of bond (X-O) (X=Si,C)
(stability consideration)
Single bond(stable) All forms of bond
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15. The Siloxane Bond - Structural Considerations
• The siloxane bond have a great impact on the chemistry of polysiloxanes.
• The Si-O bond distance, shorter than the sum of covalent radii, 1.64 Å compared to 1.76 Å
implies a partial double bond character of Si-O.
• The basicity of siloxanes is lower than that of ethers.
• The barrier of rotation around the Si-O axis, ca. 2.5 kJ /mol in (as well as the barrier of
linearisation of the SiOSi angle, ca. 1.3 kJ /mol , are very low.Thus, the polysiloxane chain is
unusually flexible.
• The Si-O-Si angle, 140-180°, is much wider than the tetrahedral angle, the silicon atom has a
relatively large size and the substituents appear only at every second atom in the chain.
• These features account for the relatively low steric hindrance to the attack of a nucleophile on
silicon.
15R.O. Jones et al. (eds.), Silicon-Containing Polymers, 3-41

16. • The propensity of silicon toward the nucleophilic attack is connected
with its electronic character
• The siloxane bond are used to be attributed to the p(O) d(Si)π interaction.
• The contribution of the d orbitals at Si to the total electron distribution is small.
• Many authors prefer to approach these features as a consequence of the strongly ionic
character of the Si-O bond and of the negative hyperconjugation p(O) σ*(Si-X)π
where X is any atom bound to silicon
• The interaction is particularly strong when X is an electronegative atom, e.g., O, F,
Cl.
• But (p-d)π concept not provide unequivocal information about the character of the Si-
O bond.
16R.O. Jones et al. (eds.), Silicon-Containing Polymers, 3-41

17. Properties of silicones
• Silicones are highly valued materials because they have a
combination of physical properties not found in other polymers.
• They have outstanding heat stability and can be used in
applications where organic materials would melt or decompose.
• Many silicones seem to be impervious to the effects of aging,
weather, sunlight, moisture, heat, cold, and some chemical
assaults.
• Numerous silicones are used to stick, bond, or couple things
together.
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18. • The chemical behaviour and physical properties of silanols
depend much on their structure.
• Generally, their reactivity increases with the number of hydroxyl
groups at the silicon atom in order
R3SiOH < R2Si(OH)2 < RSi(OH)3
• The enhanced reactivity of the monomeric polyols and the
activating influence of the silanol group on the reactivity of other
electronegative substituents at silicon are explained by the negative
hyperconjugation.
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19. Facts of relevance to the preparation and
properties of silicone polymers
• Silicon is usually tetravalent but assume hexavalent
characteristics.
• Silicon is more electropositive than carbon and hence Si-C bonds
are polar (12% ionic)
• The reactivity also depends on the nature of the attacking
molecule.
• The siloxane Si-O link has number of interesting properties.
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20. Fundamental Characteristics of PDMS
• Low intermolecular forces between methyl groups
• Compact size of methyl groups
• High siloxane backbone flexibility
• High siloxane bond energy
• Partial ionic nature of siloxane bond.
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21. Flexiblity of Siloxanes
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22. The Si-O bond – the key to silicone’s unique
properties
• The Si-O bond has higher bond energy than the C-O bond.
• The Si-O bond is longer and flatter than the C-O bond.
• The Si-O bond has a lower barrier to rotation than the C-O bond
and higher free volume.
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23. • Depending on the number of repeat units in the polymer chain and the
degree of cross-linking (how the polymer chains are tied together)
• at least six classes of commercially important families of products
can be produced:
 fluids,
 emulsions,
 compounds,
 lubricants,
 resins, and
 elastomers or rubbers.
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24. Silicones in Technology
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36. • Airbags are able to meet changing design and tougher
foldability and cushioning requirements.
• Silicones in airbags provide additional strengthening, sealing
and uniformity functionality.
• Silicone coatings also render the fabric gastight and heat.
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39. Silicone Hydrogels- a gel composed usually of one or more
polymers suspended in water
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•Silicone hydrogel contact lenses are advanced soft lenses that allow more
oxygen to pass through the lens to the cornea than regular soft ("hydrogel")
contacts.
• In fact, silicone hydrogel lenses enable up to five times more oxygen to reach
the cornea than regular hydrogel lenses.
•Benefits of silicone hydrogel lenses
Extended wear (sometimes for up to six straight nights and
days )
Continuous wear (sometimes for up to thirty days before
replacement )
Increased comfort and performance

40. • Menstrual cups are usually made of medical grade silicone,
shaped like a bell and flexible and are also used internally.
• One cup is reusable for up to five years or more
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http://www.dailymail.co.uk/news/article-3553275/Use-sea-sponges-not-tampons-Spanish-politicians-tell-women.html#ixzz55EnFKpPB

41. Breast implants
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•Implant grade silicone is of long linear
chain length often exceeding one million
molecular weight
•These implants were introduced in the
late 1980s and gained popularity in the
1990s.
X-ray of breast
implant

42. Complications
• The suspected mechanisms of breast implant rupture are:
• damage during implantation
• damage during (other) surgical procedures
• chemical degradation of the breast implant shell
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44. • Cases of a rare type of cancer that is linked to breast implants
appear to be on the rise, according to a new review.
• The first case of BIA-ALCL was documented in 1997.
• An FDA report published last year revealed 359 reported cases
and nine deaths.
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45. References
• James E. Mark,Harry R. Allcock,Robert West, Inorganic Polymers, OXFORD UNIVERSITY
PRESS,Second edition,2005.
• Vadapalli Chandrasekhar,Inorganic and Organometallic Polymers, Springer
publications,2005.
• Chatwal,G.R, Inorganic Polymers, Himalaya Publishing House, Bombay, First Edition,1996.
• Stephen J. Clarson1, John J. Fitzgerald, Science and Technology of Silicones and Silicone-
Modified Materials, ACS Symposium Series, Volume 964,August 02, 2007
• http://www.silicones.eu/silicones-uses
• https://dash.harvard.edu/bitstream/handle/1/8965609/Abrams.html?sequence=2
• http://www.brainkart.com/article/Silicones---structure-and-uses_2820/
• http://www.essentialchemicalindustry.org/polymers/silicones.html
• https://www.dowcorning.com/content/publishedlit/01-3077.pdf
• http://www.chemistryexplained.com/Ru-Sp/Silicone.html#ixzz55A0R9t00
• http://wwwcourses.sens.buffalo.edu/ce435/Polysiloxanes/#jones
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46. Thank you
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