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2
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- Silicone fluids are a very important class of compounds.
- They make up one of the largest class of silicones sold today.
- They are called silicone fluids, silicone oil, methyl fluid, PDMS, but
the INCI name is dimethicone.
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3
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4
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- Step 1 Silicon form Quartz
- SiO2 (Sand) + C (Wood)
------------>
-
1700o C
- Si and Carbon Oxides
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5
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6
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7
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- Step 2 Rochow Process (Synthesis
of Chlorosilanes)
- Si + CH3Cl
---> (CH3)2-Si-Cl2
(Predominate)
- (CH3)3-Si-Cl
- CH3-Si-Cl
-
Si-Cl4
- CH3HSiCl2
- CH3HSiCl
-
Others
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8
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- Eugene Rochow has made some of the most significant contributions to the
study and commercialization of silicon compounds.
- The “Direct Process” allowed for commercial usage over the older
“Gringnard Process”. The “Direct Process now bears Rochow’s name.
- Chemistry of Silicones (John Wiley) by Rochow published in 1946 is not
only an extremely interesting historical work, but still contains some
very enlightening data.
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9
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- Step 3 Hydrolysis of Rochow
Chlorosilanes
- Rochow Process Products + Water
------>
-
Hydrolyzate and HCl
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10
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11
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-
CH3
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- “M unit” is monosubstituted O1/2-Si-CH3
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-
CH3
-
CH3
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- “D unit” is disubstituted -
O1/2 -Si- O1/2 -
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-
CH3
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12
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-
O1/2
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- “T unit” is trisubstituted
- O1/2 -Si- O1/2
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-
CH3
-
O1/2
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- “Q unit” is Quadsubstituted
- O1/2 -Si- O1/2 -
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-
O1/2
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13
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- If organofunctional groups other than carbon are introduced, an “*”
is added to its designation.
-
CH3
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- “M* unit” is
monosubstituted -O1/2-Si-CH3
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H
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CH3
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- “D* unit” is disubstituted - O1/2-Si-
O1/2 -
- with organofunctionality
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H
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14
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-
-O1/2
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- “T* unit” is trisubstituted
- O1/2-Si- O1/2-
- with
organofunctionality
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H
- There is no “Q* unit” since there is no possibility of functional
groups.
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15
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- There are three types of construction of silicone polymers. They are:
- Comb
- CH3 CH3 CH3 CH3
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- CH3
--Si-O----(-----Si---O-)-50--( -Si----O-)-10----Si---
CH3
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- CH3 CH3 R CH3
- M D50 D*10 M
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- CH3 CH3 CH3
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- R--Si----O--(--- Si---O---)-50----Si---R
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- CH3 CH3 CH3
- M* D50 M*
- CH3 CH3 CH3 CH3
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- R----Si-O-----(--Si---O--)50 --(---Si----O---)-5---Si---R
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- CH3 CH3 R CH3
- M* D50 D*5 M*
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- CH3 CH3 CH3
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- CH3 - Si- O- (-Si-O)n- Si - CH3
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- CH3 CH3 CH3
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18
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19
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- Viscosity 25 C Approximate
- (Centistokes) Molecular Weight
- ---------------- -----------------
- 50 3,780
- 200 9,430
- 350 13,650
- 1,000 28,000
- 60,000 116,500
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- Consider silicone fluid with a viscoisty of 200, such a product has a
“molecular weight” of 9,430.
- Viscosity 25 C Approximate
- (Centistokes) Molecular Weight n value
- 200
9,430
125.2
- The math for the number of “D” units is:
- 9,430 – 164 (M groups) = 125.2
- 74
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- Is compound really:
- CH3 CH3 CH3
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- CH3 -
Si- O- (-Si-O)125.2- Si - CH3
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- CH3 CH3 CH3
- What
does 125.2 mean as a subscript?
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23
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24
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25
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- Polymers unlike Hexane are not one compound, rather they are a mixture
(composition) composed of a range of values, the average of which is
125.2 in our example.
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26
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- But what is the composition of this mixture and how do I assure it
remains constant so my formulation does not change?
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- What type of distributions exist?
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- total weight polymer molecules
- total number of polymer molecules
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30
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31
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32
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33
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- Viscosity: Less than 5 cSt
- Dodecamethylpentasiloxane (CAS# 141-63-9) (Cyclic and volatile)
- 0.65 cSt (CAS#
107-46-0) (MM)
- 1 cSt (CAS# 107-51-7)
- 3 cSt (CAS # 63148-62-9)
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34
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- They are used in a wide variety of antiperspirants, skin creams, skin
lotions, suntan lotions, bath oils, hair care products etc.
- Volatile Silicones possess low surface tensions and exhibit excellent
spreadability.
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35
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- Viscosity less than 50cSt
- 5cSt
- 10cSt
- 20cSt
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36
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- A primary use is as an ingredient in a number of personal care products
due to their high spreadability, low surface tension and subtle skin
lubricity.
- These fluids are clear, tasteless, odorless and provide a non-greasy
feel.
- They are used in a wide variety of antiperspirants, skin creams, skin
lotions, suntan lotions, bath oils, hair care products etc.
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37
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- Polydimethylsiloxanes (CAS#
63148-62-9)
- Viscosity 50 -1,000cSt
- 50 cSt
- 100 cSt
- 200 cSt
- 350 cSt
- 500 cSt
- 1,000 cSt
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- Viscosities 10,000cSt -60,000cSt
- 10,000 cst
- 60,000 cst
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39
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40
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-
Viscosity (cs)
- Temperature (oC) Silicone Fluid Petroleum Oil
- 100 40 11
- 38 100 100
- -18 350 11,000
- -37 660 230,000
- Silicone fluids have very good viscosity stability over a wide range of
temperatures.
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41
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Notes