PEG-100 Stearate is a chemical compound, an ester of stearic acid and polyethylene glycol.

The name describes the structure of the molecule:

• PEG - Stands for "Polyethylene Glycol". Indicates that the molecule is a derivative of polyethylene glycol, a water-soluble synthetic polymer.
• 100 - This number indicates the approximate molecular weight of the polyethylene glycol used, corresponding to about 100 repeating units of the monomer.
• Stearate - Derived from the word "stearic." It indicates that the molecule is a salt or ester of stearic acid, a saturated fatty acid.

Description of the raw materials used in its production:

• Polyethylene Glycol (PEG) - Polyethylene glycols are polymers of ethylene glycol. They are obtained through the polymerization of ethylene oxide. The number following the PEG prefix (as in the case of PEG-100) indicates the average molecular weight of the polymer.
• Stearic Acid - Stearic acid is a long-chain fatty acid. It is a natural component of vegetable and animal fats and is often obtained from vegetable sources such as palm oil or coconut oil.

Industrial chemical synthesis step-by-step:

• Esterification - Stearic acid and polyethylene glycols are melted together in the presence of a catalyst, such as potassium hydroxide (KOH), to form the PEG-100 Stearate ester. During this reaction, the hydroxyl group (-OH) of the polyethylene glycol reacts with the stearic acid to form the ester.
• Purification - The product obtained from the esterification reaction is purified to remove any impurities and by-products. This can be done through processes such as filtration, washing, or distillation.
• Drying and Packaging - The purified PEG-100 Stearate is dried to remove any residual moisture and then packaged for distribution and use in the cosmetic industry.

It appears in the form of a white or yellowish powder.

What it is used for and where

Cosmetics

Surfactant - Cleansing agent. Cosmetic products used to cleanse the skin utilise the surface-active action that produces a lowering of the surface tension of the stratum corneum, facilitating the removal of dirt and impurities. 

It functions also as an emollient, non-ionic dispersing emulsifier. Emulsifiers have the property of directly influencing the stability, sensory properties and surface tension of sunscreens, modulating their filmometric performance. 

Pharmaceuticals

As a pharmaceutical solvent enhancement.

Other uses

Used in industrial cleaning and textile washing. In chemical fibres it can improve fibre softness. Paper chemicals, auxiliary agents for plastics.

Safety

There is a lot of literature on PEGs that has addressed, discussed and drawn conclusions on their possible toxicity, but PEGs differ widely, as do the production techniques and the impurities present in the final products. PEG-100 Stearate does not have high penetration power into the skin and therefore no serious toxicity problems have been detected so far.

PEG-100 Stearate studies

Typical commercial product characteristics PEG-100 Stearate

Appearance	White to yellowish powder
pH	5 - 7 sol. 5%
Boiling Point	438.4±18.0 °C at 760 mmHg
Melting Point	47°C
Decomposition	>200°C
Density	0.9±0.1 g/cm3
Flash Point	164.6±14.0°C
Vapor Pressure	0.0±2.4 mmHg at 25°C
Refraction Index	1.457
PSA	46.53000
LogP	7.85
Loss on Drying	≤5.0%
Ash	≤5.0%
Heavy metals	NMT 10ppm
Arsenic	NMT 2ppm
Cadmium	NMT 2ppm
Lead	NMT 2ppm
Mercury	NMT 2ppm
Total Plate	10,000cfu/g Max
Yeast & Mold	1,000cfu/g Max
Safety

• Molecular Formula    C₂₀H₄₀O₃
• Molecular Weight      328.5
• Exact Mass    328.297760
• CAS  9004-99-3     111-60-4
• UNII    0324G66D0E
• EC Number   618-405-1    203-886-9
• DSSTox Substance ID  DTXSID5026881    DTXSID6027715    DTXSID501014774
• IUPAC  2-hydroxyethyl octadecanoate
• InChl=1S/C20H40O3/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-20(22)23-19-18-21/h21H,2-19H2,1H3
• InChl Key      RFVNOJDQRGSOEL-UHFFFAOYSA-N
• SMILES   CCCCCCCCCCCCCCCCCC(=O)OCCO
• MDL number  MFCD00148007
• PubChem Substance ID    
• ChEBI  32027    167626
• RTECS  TQ5950000    TQ5600000
• NACRES NA.24   
• NSC      31811
• RXCUI        1426255

Synonyms

• Polyoxyl 100 stearate
• Polyoxyethylene stearate
• Ethylene glycol, monostearate
• 2-hydroxyethyl octadecanoate
• Stearic acid, 2-hydroxyethyl ester

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Premise on PEG.

Since the PEG (1) family is numerous and is found in many cosmetic, cleaning and medicinal products and others, we need a cognitive premise on the subject that is rather complex from the point of view of safety because these products not only come into contact with the skin but, as in the case of medicine, they are also ingested.

PEG or polyethylene glycols polymerise the condensed ethylene oxide and water and are called polyethylene glycols, but in reality, they are complex chemical components, polymers bound together. For example,  plastic is polyethylene and has a hard consistency, while  polyethylene aggregated to the glycol forms a liquid.

The number that appears after the initials PEG represents the molecular weight and the higher this number is, the less it penetrates  the skin. 

Here below are some studies in Medicine that refer to the use of PEG Polyethylene glycol in various fields.

Intestine

Polyethylene glycol with or without electrolytes is effective for the treatment of functional constipation, both in adults and in paediatric patients, with great safety and tolerability. These preparations are the most effective osmotic laxatives (more than lactulose) and are the first-line treatment for functional constipation in the short- and long-term. They are as effective as enemas in faecalomas, avoid the need for hospitalisation and are well tolerated by patients (especially when given without electrolytes) (2).

In the preparation  for colonoscopy,  polyethylene glycol tablets confirmed efficacy, acceptability, tolerance and safety similar to those of sodium phosphate (3).

For peripheral nerve repair (4).

Eyes

Dry eye syndrome is a disorder that affects 5-34% of the world's adult population with reduced quality of life. Artificial or lubricating tears are the most used therapy for treating this condition due to their low side effects profile, which attempt to modify the properties of the tear film. Polyethylene glycol has demonstrated clinical efficacy in the treatment of this condition (5).

Brain

Polyethylene glycol facilitates the neuroprotective effects of magnesium in head injuries (6).

Tumors

For transarterial chemoembolization, Polyethylene glycol is effective and safe for the treatment of liver cancer, as indicated by good tolerability, quality of life and high tumour response (7). 

Cosmetics

Many types of PEG are hydrophilic and are used as creams, topical dermatological preparations and in cosmetic products such as surfactants, emulsifiers, detergents, humectants and skin conditioners.

Safety varies from type to type given the structural complexity (8).

References___________________________________________________________________

(1) Fruijtier-Pölloth C. Safety assessment on polyethylene glycols (PEGs) and their derivatives as used in cosmetic products. Toxicology. 2005 Oct 15;214(1-2):1-38. doi: 10.1016/j.tox.2005.06.001.

(2) Mínguez M, López Higueras A, Júdez J. Use of polyethylene glycol in functional constipation and fecal impaction. Rev Esp Enferm Dig. 2016 Dec;108(12):790-806. doi: 10.17235/reed.2016.4571/2016.

Santos-Jasso KA, Arredondo-García JL, Maza-Vallejos J, Lezama-Del Valle P. Effectiveness of senna vs polyethylene glycol as laxative therapy in children with constipation related to anorectal malformation. J Pediatr Surg. 2017 Jan;52(1):84-88. doi: 10.1016/j.jpedsurg.2016.10.021.

(3) Chaussade S, Schmöcker C, Toulemonde P, Muñoz-Navas M, O'Mahony V, Henri F. Phosphate tablets or polyethylene glycol for preparation to colonoscopy? A multicentre non-inferiority randomized controlled trial. Surg Endosc. 2017 May;31(5):2166-2173. doi: 10.1007/s00464-016-5214-1.
Tsunoda T, Sogo T, Iwasawa K, Umetsu S, Oikawa-Kawamoto M, Inui A, Fujisawa T. Feasibility and safety of bowel cleansing using low-volume polyethylene glycol with ascorbic acid before pediatric colonoscopy: A pilot study. Dig Endosc. 2017 Mar;29(2):160-167. doi: 10.1111/den.12756.

(4) Hoffman AN, Bamba R, Pollins AC, Thayer WP. Analysis of polyethylene glycol (PEG) fusion in cultured neuroblastoma cells via flow cytometry: Techniques & optimization. J Clin Neurosci. 2017 Feb;36:125-128. doi: 10.1016/j.jocn.2016.10.032.

(5) Pérez-Balbuena AL, Ochoa-Tabares JC, Belalcazar-Rey S, Urzúa-Salinas C, Saucedo-Rodríguez LR, Velasco-Ramos R, Suárez-Sánchez RG, Rodríguez-Carrizalez AD, Oregón-Miranda AA. Efficacy of a fixed combination of 0.09 % xanthan gum/0.1 % chondroitin sulfate preservative free vs polyethylene glycol/propylene glycol in subjects with dry eye disease: a multicenter randomized controlled trial. BMC Ophthalmol. 2016 Sep 20;16(1):164. doi: 10.1186/s12886-016-0343-9.

Labetoulle M, Messmer EM, Pisella PJ, Ogundele A, Baudouin C. Safety and efficacy of a hydroxypropyl guar/polyethylene glycol/propylene glycol-based lubricant eye-drop in patients with dry eye. Br J Ophthalmol. 2017 Apr;101(4):487-492. doi: 10.1136/bjophthalmol-2016-308608.

(6) Busingye DS, Turner RJ, Vink R. Combined Magnesium/Polyethylene Glycol Facilitates the Neuroprotective Effects of Magnesium in Traumatic Brain Injury at a Reduced Magnesium Dose. CNS Neurosci Ther. 2016 Oct;22(10):854-9. doi: 10.1111/cns.12591.

(7) Aliberti C, Carandina R, Sarti D, Mulazzani L, Catalano V, Felicioli A, Coschiera P, Fiorentini G. Hepatic Arterial Infusion of Polyethylene Glycol Drug-eluting Beads for Primary and Metastatic Liver Cancer Therapy. Anticancer Res. 2016 Jul;36(7):3515-21.

(8) Jang HJ, Shin CY, Kim KB. Safety Evaluation of Polyethylene Glycol (PEG) Compounds for Cosmetic Use. Toxicol Res. 2015 Jun;31(2):105-36. doi: 10.5487/TR.2015.31.2.105.