Electrospinning series you want to know—PEO (Poly ethylene oxide)

Contents

1. The properties of PEO materials

2. Application of Electrospinning PEO

3. Electrospinning PEO process

4. Common spinning problems and solutions

1.The properties of PEO materials

Poly ethylene oxide (PEO), also known as polyethylene oxide, is a white water-soluble thermoplastic material, is a kind of crystalline, thermoplastic water-soluble polymer. Most of PEO has a highly ordered structure with a relative molecular weight of 105 ~ 107 and a crystalline state. Its melting point is 65±2℃. It can be completely soluble in water and some organic solvents, and the solution has high viscosity. The molecular weight of its industrial products can vary over a wide range.

Figure 1 Molecular structure diagram

2.Application of Electrospinning PEO

Because PEO has low toxicity, complete water solubility, excellent solution rheology, combination with organic solvents, low ash content and thermoplasticity. The known solvents are: water, benzene, dimethylformamide (DMF), aliphatic hydrocarbons, diethyl ether, etc. PEO can be used as water-soluble film, textile slurry, thickening agent, flocculant, lubricant, dispersant, water phase drag reducer, cosmetic additive, antistatic agent, etc. At the same time, it is combined with electrospinning to further expand a wider range of applications:

（1）Water-soluble shell of drug：Because PEO has the characteristics of water soluble and non-toxic, PEO can be made into a fiber membrane through a specific process and covered on the outer layer of the pill, which can be made into controllable sustained release drug. It can control the diffusion rate of the pill components in the body and increase the action time of the pill effect.

Figure 2Preparation of sustained-release drug by mixed spinning of pharmaceutical polymers

（2）Functional dressings: due to PEO's good water-soluble and biological non-toxic properties, specific pharmaceutical functional materials can be added and processed into functional dressings with high porosity and complete absorption through specific technologies.

Figure 3 Medical dressings

（3）Solid cleaner: PEO has good foaming properties and is easily dissolved by water, which can make the skin soft and smooth. The PEO is processed into a solid film and only needs to be sprayed with a small amount of water to complete the transformation from solid to liquid, which eliminates the disadvantages of inconvenient carrying and troublesome storage of liquid detergent.

Figure 4 Solid cleaner

（4）Sanitary napkins and baby diapers: a water-absorbing tree or fiber membrane made of PEO after cross-linking treatment can be used for women's sanitary napkins and baby diapers.

Figure 5 Sanitary napkins and baby diapers

 （5）Nano Instant Mask: Because PEO has complete water solubility, excellent solution rheology, etc., these characteristics make PEO into nano fiber dry instant mask after being mixed with specific essence. At the same time, the solvent is water-based solvent, the production process is green and safe. For more information about Nano Instant Mask products, you can contact NanoToolman WeChat at the end of this article.

Figure 6  Nano Instant Mask

3. Electrospinning PEO process

3.1 Main materials and instruments

(1) Spinning material: PEO powder, molecular weight 200,000-600,000; Deionized water (or DMF) solvent, analytically pure.

(2) Experimental Instruments: 50mL conical flask, magnetic stirrer, water bath, electronic balance, E05 electrospinning machine /MF04-002 mass production equipment, viscometer, electrical conductivity tester.

3.2 Preparation of spinning fluid

Use an electronic balance to weigh a certain mass of solvent deionized water in a conical flask, add a magnetic agitator, and stir in a water bath. Then weigh PEO of a certain quality and slowly add it into the conical flask. Close the bottle cap tightly to prevent conical bottle from water steam; A certain concentration of PEO spinning solution can be obtained after the water bath temperature is set at 60℃ and the solution is continuously stirred and dissolved for 4h until there is no obvious aggregates in the solution.

The mass concentration of common PEO spinning solution ranges from 2%-12%. The solvent system is water, benzene, DMF, aliphatic hydrocarbons, ether.

3.3 Spinning process and parameters

The above PEO spinning liquid is pumped into a 20mL syringe, which is fixed to the syringe pump of the spinning machine, and a 20G (1/2inch, flat mouth) stainless steel needle is installed. The needle is connected to the positive pole of the high voltage power supply, the receiving roller is connected to the negative pole of the high voltage power supply, and the receiving base material is affixed to the receiving roller. The syring-pump specification is set as 20mL, the liquid supply speed is 1~5mL/h (depending on the electrospinning process), the roller speed is 300 RPM, the slide stroke is 20cm, the spinning voltage is positive 20kV and negative 5kV, the temperature is 35℃, the humidity is 40%, and the timing is 120min. Finally, the device door is closed and the exhaust is opened.

Commonly used electrostatic spinning receiving substrate: aluminum foil paper, release paper, non-woven cloth, screen cloth, etc.

4. Common spinning problems and solutions

（1）The solution has a large number of lumps: Generally due to the preparation process, the agitator or magnetic agitator fails to disperse the agglomerated powder in time. Therefore, when PEO powder is added, PEO powder is gradually added while the solvent is stirred to avoid the agglomeration problem of PEO powder.

（2）There is a layer of water on the surface of PEO spinning liquid: Generally, the water is easy to precipitate out of the mixing system after the solution has been standing for a long time. Therefore, avoid the solution standing for a long time, at the same time mix well before use it.

（3）Obvious liquid point or liquid mark on the film surface: liquid point is generally caused by too low PEO concentration in the spinning liquid, resulting in spray jet. Liquid trace is generally caused by the high concentration of PEO in the spinning liquid, which leads to the increase of solution viscosity. The jet cannot complete splitting and solidify into fiber completely under the current volatile environment and drafting force.