The document provides an overview of silicone chemistry and applications. It discusses the flexibility of siloxane bonds in silicone polymers compared to carbon polymers. Silicone polymers have low glass transition temperatures, spread easily on substrates, and are lubricating, waterproof, and thermally stable. Common silicone products include fluids, gums, resins, and elastomers. Silicone applications span many industries like aerospace, automotive, medical, and more. The document also outlines the chemistry and processes for synthesizing silicone polymers, including anionic ring opening polymerization and the use of end blockers.

1. Basic Silicone Chemistry (I)

2. Silicone Family Tree
Si
Volatile Methyl
Siloxanes
Silicone Polyethers
Silanes
Fluids & Emulsions Silicone
Resins
Dimethyl
Compounds
Organo-Silicones
Amino Silicones
Elastomers

3. Flexibility of Siloxane Chemistry
• Non-volatile
• Antifoam
• Slippery
• Water Insoluble
• Excellent Depth of Gloss
• Incompatible in Organics
• Durable
• Volatile
• Profoam
• Sticky
• Water Soluble
• Shiny
• Compatible
• Transient

4.  Aerospace
 Automotive
 Chemicals/ Petrochemicals
 Construction
 Consumer Products
 Electrical/Electronics
 Food Processing
 Industrial Maintenance Production
SILICONES APPLICATIONS
Dow Corning’s products and specialty materials are used by
customers in virtually every major industry.
 Medical Products
 Paints & Coatings
 Personal, Household & Automotive
Care
 Pharmaceuticals
 Plastics
 Pressure-Sensitive Adhesives
 Textiles & Leather

5. SILICA
O
O Si O
O
SILICON Si
SILANES Si
X
X X
X
SILOXANES O
R
R
Si O
Silicone Nomenclature

6. Silicone Nomenclature Shorthand
Precursor Silanol Siloxane Structure Short hand
Me Me
Cl-Si-Cl HO-Si-OH Linear Structures D unit
Me Me
Me Me
Me-Si-Cl Me-Si-OH End-cap group M unit
Me Me
Me Me
Cl-Si-Cl HO-Si-OH Branched Structures T unit
Cl OH
Cl OH
Cl-Si-Cl HO-Si-OH Silica Core Q unit
Cl OH
Me Me Me Me Me Me Me Me
Me-Si-O-Si-O-Si-O-Si-O-Si-Me = Me-Si-(O-Si)3-O-Si-Me =
Me Me Me Me Me Me Me Me
MD3M

7. (1) Fluids (hydraulic, release agents, cosmetics, heat transfer
media, polishes, lubricants, damping, dry cleaning)
Polymer chains of difunctional units (D) terminated with monofunctional (M)
units OR cyclics (Dx)
(2) Gums (high temperature heat transfer fluids, lubricants,
greases, cosmetic and health care additives)
Same structure as PDMS fluids, but much higher molecular weight (viscosities
>1,000,000 cSt).
(3) Resins (varnishes, protective coatings, release coatings,
molding compounds, electronic insulation)
Rigid solids based on trifunctional (T) and tetrafunctional (Q) units. Surface
modification with (M) units
(4) Elastomers (Heat cured and RTVs: tubing and hoses,
medical implants, sealants, adhesives, surgical aids,
electrical insulation, fuel resistant rubber parts, rollers, etc)
Soft solids based on crosslinked SiH Fluids
Silicone Classifications by Physical Form

8. Raw Materials
• Initial material is quartz
– SiO4/2
– 26% of the Earth’s crust
• Reduce to Si metal with carbon at 2500F
• Dow Corning purchases silicon metal & methanol
• Methanol is converted to MeCl with recycled HCl

9. Process Chemistry of Methyl Train
MeCl
Si
Copper Catalysts
Me2SiCl2
MeHSiCl2
Me3SiCl
Chlorosilane
Mix
H2O
Waste &
Recovery
Me2 Hydro
SiH fluid
EBB

10. Volatile Polydimethylsiloxane Fluids
INCI NAME: Cyclomethicone
CH3
Si - O
CH3
n = 3 Trimer
n = 4 Tetramer
n = 5 Pentamer
n = 6 Hexamer
n
PENTAMER (D5)
Si
Si
Si
Si
Si
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
O O
O
O
O
CH3
CH3

11. Volatile Polydimethylsiloxane (PDMS) Fluids
When m = 0, R= CH3 called Hexamethyldisiloxane or 200 Fluid,0.65 cS
(.65,1, 1.5 and 2.0 cS are volatile)
CH3 CH3 CH3
R - Si - O - Si - O - Si - R
CH3 CH3 m CH3
R = CH3 INCI: Dimethicone
R = OH INCI: Dimethiconol

12. Properties of Siloxanes
• Despite the Fact that Silicon and Carbon are both Group IV
elements their chemistry is very different
• Unique flexibility of Si-O bond
• Si-O-Si C-C-C C-O-C units
bond length 1.63 1.54 1.42 angstroms
bond angle 130 112 111 degree
bond energy 106 83 86 Kcal/mol
bond barrier 0.2 3.6 2.7 Kcal/mol

13. •Barrier to Rotation ( kcal/mole )
–Polyethylene 3.3
–Polytetrafluoroethylene 4.7
–Polydimethylsiloxane < 0.2
Key Point: Siloxane (Si-O-Si) polymers are
stronger than carbon polymers, yet the polymer
chains are more open and flexible
Siloxane Polymers vs Carbon Polymers

14. Siloxane Physical Properties
• Very low glass transition temperature (Tg = -120 °C)
– high molecular weights but not a solid
• Ability to spread out on a wide variety of substrates
– silky, smooth, non-tacky, aesthetic enhancing
– flowability and film forming
• Lowest surface shear viscosity and low surface tension
– lubricating, antifoaming, waterproofing, release properties
• High gas permeability
• Excellent dielectric properties
• Very good thermo-oxidative stability
– good chemical inertness and temperature resistance

15. Anionic Ring Opening Equilibrations
O Si O Si
Me
Me
n
Me
Me
O
K K
O Si O Si
Me
Me
7
D4
Me
Me
O
K K
O Si O Si
Me
Me
n
R
R
R
Si
R
R
R
O
Si
O Si
O
Si
O
Si
Me
Me
Me
Me Me
Me
Me
Me HO Si O Si
Me
Me
3
KOH
Me
Me
O K
D4
Si O Si
R
R
R
R
R
R
Ring : Chain Equilibrium
10-15% : 85 – 90%
PDI = 2.0

16. Anionic Ring Opening Equilibrations
Si O Si
CH3
CH3
CH3
CH3
H3C
CH3
Si O Si
CH3
CH2CH2CH2NH2
CH3
CH3
H2NCH2CH2CH2
CH3
Si O Si
CH3
CH3
CH3
CH3
NH2
H2N
Si O Si
R
R
R
R
R
R
End Blockers
Si O Si
CH3
CH3
CH3
CH3
O
O
O
O
O
O

17. Anionic Ring Opening Equilibrations
Si O Si
CH3
CH3
CH3
CH3
H3C
CH3
End Blockers
Viscosity
time
Maximum in viscosity involves incorporation
of end blocker (which is less reactive than cyclic)

18. Living Anionic Ring Opening Polymerization
O Si O
Me
Me
n
Si
CH3
CH
CH3
CH3
CH2
H3C Li
D3
10% THF
O Si O
Me
Me
2
Si
CH3
CH
CH3
CH3
CH2
H3C Li
cyclohexane
O
Si
O
Si
O
Si
H3C CH3
CH3
CH3
H3C
H3C
D3
sec-Butyl – Li +
O Si O
Me
Me
n
Si
CH3
CH
CH3
CH3
CH2
H3C
LiCl
Si
R
R
R
Cl
Si
R
R
R
Living anionic polymerization