Preparation process of nanocellulose electrospinning

1. Introduction

Electrospinning is a technology that prepares polymer solution or melt into nanofibers through high voltage electric fields. In recent years, nanocellulose has become a hot material for electrospinning research due to its excellent mechanical properties, biocompatibility and degradability. prepared by electrospinning Nanocellulose fibers have broad application prospects in the fields of filtration, biomedicine, energy storage, etc. This article will introduce in detail the preparation process of nanocellulose electrospinning method.

2. Experimental materials

Cellulose raw materials : microcrystalline cellulose ( MCC), lignocellulose or bacterial cellulose (BC).

Solvents : N,N-dimethylformamide (DMF), acetone, ethanol, ionic liquids (such as 1-ethyl-3-methylimidazole acetate, [EMIM][OAc]), etc.

Additives : polyvinyl alcohol ( PVA), polyethylene oxide (PEO), chitosan, etc., used to adjust the viscosity and electrospinning properties of the solution.

Crosslinking agents : glutaraldehyde ( GA), epoxychlorohydrin, etc., are used to enhance the mechanical properties and stability of fiber membranes.

3. Experimental equipment

Electrospinning equipment :

High voltage power supply ( 0-30 kV).

Syringe pump (used to control solution flow rate).

Metal needle (usually stainless steel needle, diameter 0.5-1.0 mm).

Collector (flat plate or drum type, used to collect fibers).

Auxiliary equipment :

Magnetic stirrer (for dissolving cellulose).

Ultrasonic cleaner (for dispersing cellulose solution).

Vacuum drying box (for drying fiber membranes).

4. Preparation process steps

4.1 Preparation of cellulose solution

Dissolve cellulose :

Add cellulose raw materials to solvents (such as DMF or ionic liquids).

Heat to 60-80°C and stir for 4-6 hours until the cellulose is completely dissolved.

If an ionic liquid is used, it must be carried out under the protection of an inert gas (such as nitrogen) to prevent oxidation.

Adjust solution performance :

Add appropriate amount of additives (such as PVA or PEO) to adjust the viscosity and conductivity of the solution.

Continue stirring for 2-3 hours to ensure the solution is uniform.

The cellulose was further dispersed by ultrasonic treatment for 10-20 minutes.

Filtration solution :

The solution was filtered with a 0.45 μm or 0.22 μm filter membrane to remove undissolved particles and impurities.

4.2 Electrospinning process

Filling solution :

The prepared cellulose solution is loaded into a syringe and fixed to the syringe pump.

Make sure the needle is bubble-free and avoid interruptions in the electrospinning process.

Set electrospinning parameters :

Voltage : 10-30 kV (adjusted according to solution properties and fiber diameter requirements).

Injection speed : 0.1-2 mL/h (low speed is conducive to the formation of uniform fibers).

Receiving distance : 10-20 cm (the distance is too short may cause the fiber to be understretched, and too long may cause the fiber to be broken).

Environmental conditions : The temperature is controlled at 20-25°C and the relative humidity is controlled at 40-60%.

Start the electrospinning equipment :

Turn on the high-voltage power supply and syringe pump, the solution forms a Taylor cone under the action of an electric field and stretches it into nanofibers.

The fibers fly in an electric field and deposit on the collector to form a nanofiber membrane.

Collect fiber membranes :

Select the collector type (panel type or roller type) according to your needs.

The collection time is usually 1-4 hours, depending on the thickness requirements of the fiber membrane.

4.3 Post-processing

dry :

The collected fiber membranes were placed in a vacuum drying chamber and dried at 40-60°C for 12-24 hours to remove residual solvent.

Crosslinking processing :

Soak the fiber membrane in a solution of crosslinking agent (such as glutaraldehyde) and treat for 1-2 hours.

After removal, rinse with deionized water to remove the unreacted crosslinking agent.

Dry again to obtain a stable nanocellulose fiber membrane.

5. Process optimization

Solution concentration : Too high concentration will lead to an increase in the fiber diameter, and too low will make it difficult to form continuous fibers. Usually the cellulose concentration is controlled at 5-15 wt%.

Voltage and Injection Speed : High voltage and low injection speed are conducive to the formation of fine fibers, but the fiber breakage must be avoided.

Ambient temperature and humidity : Too high humidity may lead to fiber adhesion, and too low humidity may lead to increased fiber brittleness.

6. Application prospects

Filtration material : Nanocellulose fiber membranes have high specific surface area and porosity, and are suitable for high-efficiency air filtration and water treatment.

Biomedical : Can be used to prepare tissue engineering stents, wound dressings, and drug sustained release carriers.

Energy field : as a lithium-ion battery separator or supercapacitor electrode material.

Composite materials : used to enhance the mechanical properties of polymer-based composites.

7. Conclusion

Electrospinning is an efficient and controllable preparation method for nanocellulose. By optimizing solution properties, electrospinning parameters and post-treatment processes, nanocellulose fiber materials with excellent properties can be obtained. This method has broad application potential in many fields, and further research can be used to improve the performance and large-scale production capacity of fibers in the future.

The above is a detailed description of the preparation process of nanocellulose electrospinning. I hope it will be helpful to you!