Silicone Polymers –Unique Chemistry

Tony O’LenickSiltech Inc.

Lawrenceville, Ga 30043

August 21, 2019

Presentation

1. Define Annex XV

2. Why Silicone polymers ? Why now?

3. Biogas

4. Introduction Silicone Chemistry

5. PDMS (Silicone Fluids)

6. PEG PPG Dimethicone

7. Hydrolysis

8. Recommendations

Annex XV

3. By way of derogation, paragraph 1 shall not apply to:

a. Uses at industrial sites (except for Dry cleaning industrial sites), and uses as a transported isolated intermediate, provided that the conditions in points (a) to (f) of Article 18(4) of the REACH regulation are met.

b. Medical devices used for the treatment of scars and wounds.c. Medical devices used for the care of stoma.d. Use of D5 for dry cleaning in systems where the washing liquid is recycled or

incinerated and where there is no release to air or wastewater. e. [Mixtures used as sealants in construction that contain the substance(s) in a

concentration equal to or greater than [x % w/w] of each substances.

Why Silicones…Why NOW?

Biogas

Biogas

• Biogas can be produced from biomass such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste. Biogas is a renewable energy source.

https://en.wikipedia.org/wiki/Biogashttp://www.scientificspectator.com/environmental-spectator/

• Biogas is primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulfide (H2S), moisture and siloxanes.

Biogas

• The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen.

• This energy release allows biogas to be used as a fuel; it can be used for any heating purpose, such as cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat.

Biogas

Biogas

Biogas

• Some biogas contains siloxanes. They are formed from the anaerobic decomposition of materials commonly found in consumer products. During combustion of biogas containing siloxanes, silicon is released and can combine with free oxygen or other elements in the combustion gas. Deposits are formed containing mostly silica (SiO2) and can contain calcium, sulfur, zinc, phosphorus.

Volatile organic silicon compounds: the most undesirable contaminants in biogases

Aure ́ lie Ohannessian, Vale ́ rie Desjardin, Vincent Chatain and Patrick Germain

Water Science & Technology—WST | 58.9 | 2008

•Recently a lot of attention has been focused on volatile organic silicon compounds (VOSiC) present in biogases.

They induce costly problems due to silicate formation during biogas combustion.

•It is already known that these VOSiC originate from polydimethylsiloxanes (PDMS) hydrolysis. PDMS (silicones) are

used in a wide range of consumer and industrial applications. PDMS are released into the environment through

landfills and wastewater treatment plants.

•There is a lack of knowledge concerning PDMS biodegradation during waste storage. Consequently,

understanding PDMS behavior in landfill cells and in sludge digester is particularly important.

Analytical methodology for sampling and analysing eight siloxanes and trimethylsilanol in biogas from different wastewater treatment plants in Europe

J. Raich-Montiua,∗, C. Ribas-Fontb, N. de Arespacochagaa, E. Roig-Torresb, F. Broto-Puigb, M. Crestc, L. Bouchya, J.L. Cortinaa

Analytica Chimica Acta 812 (2014) 83–91

• A method for the speciation of silicon compounds in biogas was developed using gas chromatography

coupled with mass spectrometry working in dual scan/single ion monitoring mode. The optimized conditions

could separate and quantify eight siloxane compounds (L2 , L3 , L4 , L5 , D3 , D4 , D5 and D6 ) and

trimethylsilanol within fourteen minutes. Biogas from five waste water treatment plants located in Spain,

France and England was sampled and analysed using the developed methodology.

Behavior and adsorptive removal of siloxanes in sewage sludge biogas

K. Oshita, Y. Ishihara, M. Takaoka, N. Takeda, T. Matsumoto, S. Morisawa and A. Kitayama

Water Science & Technology—WST | 61.8 | 2010

The levels of the linear siloxanes L2, L3, and L4 and the cyclic siloxane D6 were below detection limits;

D3, D4, and D5 were detected at average concentrations of 0.66, 6.1, and 25.5mg/m3N, respectively.

From this result, we concluded that most of the siloxanes present in biogas are cyclic and that D4

and D5 are the main constituents. Schweigkofler & Niessner (1999; 2001) also reported that the main

constituents of siloxanes present in biogas are D4 and D5, at concentration ranges of 2.9 to 8.2 mg/m3N

and 2.8 to 15.5mg/m3N, respectively.

Where is the D4 and D5?

Introduction

Silicone polymers are unique materials, not just in terms of unique

properties, like film formation and surface tension reduction, but also

they are made using chemistry that is very different from the organic chemistry that is used for other

cosmetic raw materials.

This results in not only advantages to the formulators, but also imposes

some limitations on some formulation, for example limiting the

pH range of formulations. This presentation will address both

aspects of the uniqueness.

Basic Types of Silicones

1. Cyclic

D42. Silicone Fluids

ConstructionPolymer Backbone

Preparation

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Silicone Compounds

• The “Construction” relates to the polymer backbone. It is prepared by reacting various silicone precursors to make the “silicone backbone”. The “M”, “D”, “T” are part of the construction.

• The “Functionalization” relates to the functional groups that are present. They are generally a direct consequence of Si-H groups reacted with unsaturated groups in a process called “Hydrosilylation”.

• “Construction” “Functionalization” and “Derivatization ” result in the properties of the compound. Both are rarely disclosed making proper selection of a product difficult.

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Construction (Silicone Portion)

CH3|

“M unit” is monosubstituted -O1/2 -Si-CH3|CH3

CH3|

“D unit” is disubstituted - O1/2 -Si- O1/2 -|CH3

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- O1/2|“T unit” is trisubstituted - O1/2 -Si- O1/2|

CH3

-O1/2|“Q unit” is Quadsubstituted - O1/2 -Si- O1/2 -

|-O1/2

Construction (Silicone Portion)

If organofunctional groups other than carbon are introduced, an “*” is added to its designation.

CH3|

“M* unit” is monosubstituted -O1/2-Si-H|CH3

CH3|

“D* unit” is disubstituted - O1/2-Si- O1/2 -|H

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Construction (Silicone Portion)

-O1/2|

T* unit” is trisubstituted - O1/2-Si- O1/2-|H

There is no “Q* unit” since there is no possibility of functional groups.

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Construction (Silicone Portion)

Construction

CH3 CH3 CH3 CH3| | | |

CH3 --Si-O----(-----Si---O-)-50--( -Si----O-)-10----Si--- CH3| | | |

CH3 CH3 R CH3

M D50 D*10 M

• There are three types of construction of Silicone polymers.• They are:

1. Comb

Construction

CH3 CH3 CH3| | |

R--Si----O--(--- Si---O---)-50----Si---R | | | CH3 CH3 CH3

M* D50 M*

• They are:2. Linear

Construction

CH3 CH3 CH3 CH3| | | |

R----Si-O-----(--Si---O--)50 --(---Si----O---)-5---Si---R | | | |

CH3 CH3 R CH3

M* D50 D*5 M*

• They are:3. Multifunctional

%ae]l̀ a[gf]

Silicone FluidsDimethiconeSilicone Oil

Dimethicone

• In 2006, European production was 480,000 tons. This represents a silicone consumption around 1 kg per inhabitant per year in Western Europe and North America.

• Silicone fluids, represents more than 50% of the volume of silicone consumed, making polydimethylsiloxanes (PDMSs) the most widely used silicone.

• Due to their intensive production, PDMSs can be found in all environmental compartments: sediments, soils, water, air.

Method for Making Dimethicone

Equilibration Reaction of Silicone Fluids

• What is no clear from the literature is if the equilibrium mixture made by the build up process is the same as that of the break down process.

• If the reaction is a true equilibrium, it should not matter which path the reaction takes, but should be only determined by the ratio of reactants introduced.

Methodology

%ae]l̀ a[gf] dma\ 4lm\q

Material A B C D E

D4 99.40 99.40 98.80

MM 0.60 0.60 0.60 1.20

Sulfuric Acid 5.00 5.00 5.00 5.00

Sodium Bicarbonate 15.00 15.00 15.00 15.00

Commercial F1000 99.40

Commercial F350 100.00

120.00 120.00 120.00 120.00 100.00

A is 1,000 cst - build up

B is 350 cst made by reacting MM with F 1,000 (break down)

C is 1,000 cst (build up) broken down to 350 cst.

D is 350 cst build up

E is commercial 350 cst

Build up% D4

F350 4.65F1000 3.05

Break DownF350 5.29

CommercialF-350 1.58 Stripped

Build up and break downSample C 10.39

Reaction Fluid D4 TotalA 96.95 3.05 100.00B 94.71 5.29 100.00C 89.61 10.39 100.00D 95.35 4.65 100.00E 98.42 1.58 100.00

DimethiconeFluid Study

Implications

If a stripped silicone fluid having a low level of D4 is exposed to

high or low pH it will “re-equilibrate” generating new D4 and a lower molecular weight

fluid.

Likewise, if a stripped silicone fluid having a low level of D4 is

placed in a formulation having a high or low pH it can “re-

equilibrate” generating new D4 and lower molecular weight

fluid over time.

Water Science & Technology | 68.4 | 2013

Rate of Break Down Silicone Fluid

pH (mg Si/liter)/day1 2 0.072 6 0.0023 12 0.28

Water Science & Technology | 68.4 | 2013

Functional Fluid • What about organofunctional silicone polymers?

PEG/PPG Dimethicone

• R is –(CH2) 3-O-(CH2CH2-O)x-(CH2-CH(CH3)-O)yH

Hydrolytic Stability of SilSoft DimethiconeCopolyols

Time To Reach 95 % and 80 % Unhydrolyzed Material for PEG-8 Dimethicone at Different pH Levels and Concentrations

1 1 % Dimethicone Copolyol 5 % Dimethicone Copolyol80 % Unhydrolyzed 95 % Unhydrolyzed 80 % Unhydrolyzed 95 % Unhydrolyzed

pH Time(Days)

Time(Days)

2 1.29 0.63 2.54 1.20

3 14.00 7.00 27.00 13.00

4 26.00 14.00 50.00 24.00

5 45.00 23.00 89.00 35.00

6 97.00 43.00 186.00 82.00

7 >> 2 Years

8 86.00 40.00 165.00 76.00

9 42.00 19.00 82.00 38.00

10 19.00 10.00 35.00 19.00

11 9.00 4.80 17.00 9.00

12 0.82 0.39 1.72 0.75

Designation INCI MW 5% in Water Type

What about silicones in cosmetics after use?

What About Silicones in Cosmetics After Use?

• All cosmetics get washed off of the skin and go into:• Landfill• Waste treatment.

• Then what?

• They become a part of Biomass…• Which ultimately turns into volatile materials

What do we do?

What do we do?

• What is the difference between Dimethicone and Methicone and how does it relate to D4?

• The first part of the question we addresses in this column ten years ago on August 5, 20091

• The reason to look at this question again is due to the fact that what we expect from our cosmetic products is ever evolving.

• As the quest for ever lower levels of D4 (Cyclotetrasiloxane) in silicone polymers continues, the one approach will shift to polymers that are free of D4. One approach is to replace dimethicone polymers with methicone polymers.

https://www.cosmeticsandtoiletries.com/research/chemistry/52216927.html

Methicone polymers are not made

from D4, consequently they do

not produce any D4 biogas.

% Composition D4 % Composition D4

1,000 visc fluid a = 376

27,824 MWU = D Units164 MWU = M Units

27,988 Total MW

% D = 27,824/27,988 = 99.4% Wt% MM = 0.6% wt

% Composition D4

Ethyl methicone b=376

33,088 MWU =D Units164 MWU =M Units

33,252 Total MW

% D = 0.0% Wt

% Composition D4 % Composition D4

% Composition D4

PEG 8 Dimethiconea = 4 b=10

740 MWU D Units2,345 MWU D* Units

164 MWU = M Units3249 Total MW

% D = 22.7% Wt% MM = 0.5% Wt% D* = 72.5%

% Composition D4 % Composition D4

% Composition D4

PEG 8 Methicone

a = 0b= 5

0 MWU D Units2,345 MWU D* Units

164 MWU = M Units2509 Total MW

% D = 0 % Wt%D*= 93.5% Wt% MM = 6.5% Wt

% Composition D4 % Composition D4

D4 Production Study

• Synthetic Preparations of Silicone Surfactants• 10 % solutions of PEG-8 Dimethicone and PEG-8 Methicone in H2O @

pH of 4.0.• Twelve 1.00 g samples of each product were analyzed over the course

of 3 months. • Samples were evaluated via GC coupled with a Headspace adapter.

Thanks to Brandon Lines of Siltech for help with analytical methods.

Instrumentation

• Agilent 6890 w/ Headspace Adapter Running Chemstation

• Column: Zebron ZB-WAXplus, GC Cap. Column 30 m x 0.25 mm x 0.50 µm, Ea

• Method Parameters: Headspace GC/FID• HS- Sample temp – 80c for 15 minutes, transfer line and valve – 90c, sample mixed – 0.5 min, vial pressure 10psi, loop fill – 0.3min, injection time – 0.20min.

• GC- Inlet – 200c, 8.3psi, 85mL/min N2, 50:1 Split• Column – Constant flow, 30cm/sec N2 (ZB wax 30mx0.32IDx0.50um)• Oven – 50c – 5min, 20c/min to 150c with 2min hold, post run 1min @50c. • Detector – 240c, 40mL/min H2, 450 mL/min Air, 30mL/min makeup N2.

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100 ppm D4, D5, & D6

2.5

5.8 8.0

PEG-8 Dimethicone (week 1)

No Cyclic

PEG-8 Dimethicone (week 3)

Cyclic

PEG-8 Methicone (week 1)

No Cyclic

PEG-8 Methicone (week 6)

Visual 1 week at pH of 10

1% PEG 8 Methicone1% PEG 8 Dimethicone

% Composition D4 % Composition D4 Methicone vs Dimethicone Copolyol

Thank you

Questions ?

tolenick@mindspring.com