Polyethylene oxide (PEO), also known as polyethylene glycol is a polymer that dissolves in water, forming viscous solutions. It’s used in various applications such as pharmaceuticals, ceramics, and as a thickening agent in personal care products.
| IUPAC Name | Poly(oxyethylene) |
| Molecular Formula | (C2H4O)n |
| CAS Number | 25322-68-3 |
| Synonyms | Polyethylene glycol; PEG, PEO |
| InChI | InChI=1S/C2H4O/c1-2-3/h2-3H,1H3 |
Polyethylene Oxide Properties
Polyethylene Oxide Formula
The formula of polyethylene oxide is (C2H4O)n, where “n” represents the number of repeating units in the polymer chain. Each repeating unit consists of two carbon atoms, four hydrogen atoms, and one oxygen atom.
Polyethylene Oxide Molar Mass
The molar mass of PEO varies depending on the number of repeating units (n) in the polymer chain. Since the formula is (C2H4O)n, the molar mass can be calculated by adding the atomic masses of two carbon atoms, four hydrogen atoms, and one oxygen atom.
Polyethylene Oxide Boiling Point
PEO has a relatively high boiling point compared to many other organic compounds. The exact boiling point depends on factors such as the molecular weight and the presence of impurities. Generally, it has a boiling point range between 300°C and 400°C.
Polyethylene Oxide Melting Point
PEO has a relatively low melting point. The melting point depends on the molecular weight and can range from approximately 50°C to 70°C. Higher molecular weight PEO tends to have a higher melting point.
Polyethylene Oxide Density g/mL
The density of PEO varies depending on the molecular weight and the specific form of the polymer. Generally, the density ranges from about 1.1 g/mL to 1.3 g/mL. However, it’s important to note that the density can be influenced by the presence of impurities or additives.
Polyethylene Oxide Molecular Weight
PEO is a polymer with a wide range of molecular weights. The molecular weight determines the physical properties and behavior of the polymer. It can vary from a few thousand to several million grams per mole, depending on the desired application and polymerization process.
Polyethylene Oxide Structure
PEO has a linear polymer chain structure, where each repeating unit is connected to the next through an oxygen atom. This structure gives the polymer its unique properties, such as solubility and the ability to form viscous solutions in water.
Polyethylene Oxide Solubility
PEO is highly soluble in water. When dissolved in water, it forms viscous solutions due to the interaction between the polymer chains and water molecules. The solubility of PEO can also be affected by factors such as temperature, molecular weight, and concentration.
| Appearance | White solid |
| Specific Gravity | 1.1 – 1.3 g/mL |
| Color | Colorless |
| Odor | Odorless |
| Molar Mass | Varies (depending on n) |
| Density | 1.1 – 1.3 g/mL |
| Melting Point | 50°C – 70°C |
| Boiling Point | 300°C – 400°C |
| Flash Point | Not applicable |
| Water Solubility | Soluble |
| Solubility | Soluble in water |
| Vapor Pressure | Low |
| Vapor Density | Not available |
| pKa | Not applicable |
| pH | Neutral |
Polyethylene Oxide Safety and Hazards
PEO is considered to be relatively safe when handled properly. However, like any chemical substance, certain precautions should be taken. Direct skin contact should be avoided as it may cause irritation or sensitization in some individuals. Inhalation of dust or mist should be minimized, as it can irritate the respiratory system. Adequate ventilation is recommended when working with PEO to prevent the buildup of vapors. In case of accidental ingestion, medical attention should be sought. It is important to follow proper storage and handling procedures, including keeping it away from sources of ignition. Overall, practicing good laboratory and workplace safety measures is crucial when working with PEO.
| Hazard Symbols | None |
| Safety Description | Handle with proper ventilation. Avoid direct skin contact. Minimize inhalation of dust/mist. |
| UN IDs | Not applicable |
| HS Code | 3907.20 |
| Hazard Class | Not classified |
| Packing Group | Not applicable |
| Toxicity | Low toxicity |
Polyethylene Oxide Synthesis Methods
PEO synthesis employs different methods. One commonly used approach involves polymerizing ethylene oxide monomers. This process requires reacting ethylene oxide with an initiator or catalyst, such as an alkali metal hydroxide or an acidic compound. The initiator opens the ring structure of ethylene oxide, allowing the monomers to join and form the PEO polymer chain.
Another method utilizes anionic polymerization of ethylene oxide using an alkali metal alkoxide or alkali metal hydride as a catalyst. This method enables control over molecular weight and the production of well-defined PEO structures.
The ring-opening polymerization of ethylene oxide derivatives, such as epichlorohydrin or ethylene carbonate, through the use of a catalyst, results in the formation of PEO chains.
Living polymerization or controlled radical polymerization methods allow for the precise production of PEO with specific molecular weights and narrow polydispersities.
Various polymerization techniques facilitate the synthesis of PEO, allowing for the production of PEO with different molecular weights, structures, and properties based on the desired application.
Polyethylene Oxide Uses
PEO has various applications in different fields due to its unique properties. Some common uses include:
- Pharmaceuticals: It acts as an excipient in drug formulations, enhancing the solubility and bioavailability of poorly soluble drugs.
- Ceramics: It functions as a binder in ceramic processing, aiding in shaping and providing green strength to ceramic bodies.
- Personal care products: It serves as a thickening agent in lotions, creams, and shampoos, imparting viscosity and stability.
- Adhesives: It is a component in adhesive formulations, providing bonding properties and flexibility.
- Textiles: It finds application in textile processing as a sizing agent, promoting better weaving and reducing yarn breakage.
- Paper industry: It acts as a retention aid, improving the retention of fine particles in the papermaking process and enhancing paper strength.
- Solid electrolytes: Solid-state batteries and fuel cells utilize it as a solid electrolyte because of its high ionic conductivity.
- Water treatment: It aids in the flocculation of suspended particles in water treatment processes, facilitating their removal.
- Controlled release systems: It contributes to the development of drug delivery systems for the controlled release of drugs over an extended period.
- Packaging: It functions as a moisture barrier in food packaging, protecting the contents from moisture absorption.
- Lubricants: It serves as a lubricating additive in various applications, reducing friction and wear.
Questions:
Q: How to make polyethylene oxide?
A: PEO can be made by polymerizing ethylene oxide monomers using initiators or catalysts, such as alkali metal hydroxides or acidic compounds.
Q: Does polyethylene oxide gels at high temperature?
A: PEO can form gels at high temperatures due to its thermoresponsive properties, transitioning from a liquid to a gel-like state.
Q: Is polyethylene oxide biodegradable?
A: No, PEO is not readily biodegradable as it has high resistance to enzymatic degradation.
Q: Is acetone compatible with “polyethylene oxide”?
A: Yes, acetone is generally compatible with PEO and can be used as a solvent for it.
Q: What is polyethylene oxide?
A: PEO is a polymer with a chain-like structure composed of repeating units of ethylene oxide.
Q: Is diffusion-limited oxidation a concern for polyethylene?
A: Diffusion-limited oxidation is not typically a concern for polyethylene, as it has good resistance to oxidative degradation.
Q: Is polyethylene oxide soluble in ethanol?
A: Yes, PEO is soluble in ethanol, forming clear solutions.
Q: Is polyethylene oxide thermogel?
A: Yes, PEO can exhibit thermogelling behavior, forming gels or gel-like structures upon heating.
Q: Is polyethylene oxide safe?
A: PEO is generally considered safe when handled properly, but precautions should be taken to avoid direct skin contact and inhalation of dust/mist.