Poly(ethylene glycol) and Poly(ethylene oxide)

Polyethylene glycol is formed by the stepwise addition polymerization of ethylene oxide and water or ethylene glycol. It has good water solubility and good compatibility with many organic components. Because of its excellent lubricity, moisture retention, and dispersibility, it is widely used in cosmetics, pharmaceuticals, chemical fiber, rubber, plastics, papermaking, paint, electroplating, pesticides, metal processing, and food processing industries. Polyethylene oxide is also known as ethylene glycol ether. It is a substance with different degrees of polymerization made from ethylene oxide, and also a kind of polyether. It is thermoplastic and soluble in chloroform, dichloroethane, thermobenzene, or toluene, which can be used for casting plastic processing, or making thin films to package agricultural pharmaceuticals, ink powder, detergents and medicines, etc. It is a viscous liquid formed by dissolving in water and can be used as a thickener and adhesive. The resin obtained by copolymerization with propylene oxide is an important component of polyurethane foam.

Figure 1. The structural formula of polyethylene glycol.

Figure 2. The structural formula of polyethylene oxide.

Applications:

• Biomedical field: Medical polyethylene glycol is also known as polyethylene oxide. The aqueous solution of polyethylene oxide is applied to the outer layer of the pill to make a controlled release drug, which has been widely used in the pharmaceutical industry. It can control the diffusion rate of the pill components in the body and improve the efficiency of the pill. Because polyethylene oxide is non-toxic and gel-forming, it can be used as one of the components of dental prostheses. It acts as a buffer between the denture and the mouth and also helps reduce unpleasant odors and tastes. The polyethylene oxide aqueous solution is a pseudoplastic liquid, and its sensitivity to shear rate can be used as a liquid for contact lenses. Because bacteria can hardly grow on polyethylene oxide, they can maintain contact sterility. Polyethylene glycol can be used as a compounding agent for medical ointments, a binder for compressed pharmaceutical tablets, a mold release agent, cosmetics, etc.
• Light industry textile field: Polyethylene glycol-1000 and polyethylene glycol-1500 can be used as bases or lubricants and softeners in the textile and cosmetic industries. It can also be used as a dispersant in the coating industry to improve the water dispersibility and flexibility of the resin. In the rubber industry, it can be used as a dispersant to promote vulcanization and as a dispersant for carbon black fillers. Polyethylene oxide solution can be used as a skin cleansing agent, such as detergent, hand soap, etc., which will make the skin feel soft and smooth. It can also be used as a component of toothpaste to obtain smooth and stable toothpaste. It is also used as a component of shaving cream to form a thin film on the face to achieve shaving without foaming. The absorbent tree made by cross-linking polyethylene oxide can be used in sanitary napkins and baby diapers. Due to its thickening and pseudo plasticity, polyethylene oxide is also very useful in malt beverages such as the beer industry, which can achieve the effect of stabilizing foam. When polyester, polyamide and polyolefin resins are melt-spun, the addition of polyethylene oxide can improve the antistatic properties and dyeability of the fibers.

Figure 3 Molecular structure of poly(ethylene oxide).

References:

1. Cheng SZD, Chen J. (1991) "Nonintegral and integral folding crystal-growth in low molecular mass poly(ethylene oxide) fractions." J Polym Sci B Polym Phys. 29:311-327.
2. Balijepalli S, Schultz J, Lin J. (1996) "Phase behavior and morphology of poly (ethylene oxide) blends." Macromolecules. 29:6601-6611.