Electrospining: Preparation of ethyl cellulose bimodal nanofibrous membrane for high-performance air filtration based on green electrospinning with molecular weight control

Background

In recent years, flexible and wearable electronics, as prominent technological trends in future lifestyles, have attracted widespread interest in the fields of artificial skin, rollable displays, smart clothing, smart glasses, smart textiles, and implantable medical devices (Figure 1). With the increasing demand for smart electronic products, people are unremittingly pursuing advanced flexible rechargeable power sources with high energy density and reliable electrochemical performance. Undoubtedly, lithium-ion batteries dominate various electronic devices with their advantages such as high energy density, high output voltage, and low self-discharge, and are the main energy source for today's flexible electronic products. However, the scarcity and uneven distribution of lithium resources, the potential leakage of organic electrolytes, and the risk of corrosion have greatly limited the further application of lithium-ion batteries. Therefore, it is imperative to explore a new generation of highly safe, environmentally friendly, and low-cost rechargeable flexible batteries.

The main point of this paper

Application of Nanofiber Membranes in Air Filtration:

Nanofiber membranes are widely used in air filtration due to their ultrafine diameter, high specific surface area and large porosity.

Electrospinning Technology:

Electrospinning is a simple and versatile method for preparing nanofiber membranes, and hundreds of polymers have been used in this process.

Limitations of Petroleum Derivatives:

Traditional petroleum-derived polymers (such as PVP, PAN, PVDF) have poor biodegradability and are prone to environmental pollution.

Advantages of Biomaterials:

Biomaterials such as proteins and polysaccharides have good biodegradability and biocompatibility and come from a wide range of sources, including animals and plants.

Green Electrospinning:

Green electrospinning uses green solvents such as ethanol and water instead of toxic and harmful solvents to improve environmental friendliness.

Challenges of Biomaterials:

Biomaterials tend to aggregate in alkaline solutions, affecting electrospinnability and shelf life, limiting their application in air filtration

Preparation of ethyl cellulose bimodal nanofiber membrane by green electrospinning technology: high performance air filtration and sustainable development

Importance of green electrospinning technology:

Green electrospinning technology is an important way to alleviate the environmental and energy crisis, especially in the preparation of bio-based air filtration membranes.

Challenges in the development of biomaterials:

Currently, the development of biomaterials and methods for regulating membrane structure is still insufficient, and more research and innovation are needed.

Application of ethyl cellulose (EC):

EC bimodal nanofiber membranes were successfully prepared by electrospinning with ethanol and water as solvents, achieving high-performance air filtration.

New strategy for bimodal fiber forming:

A new strategy for bimodal fiber forming based on molecular weight modulation was proposed. The medium molecular weight EC polymer chain has the highest degree of heterogeneity in solvent intrusion, resulting in uneven jet stretching to form a bimodal structure.

Air filtration performance of EC membrane:

EC membranes exhibit excellent air filtration performance, with a filtration efficiency of 99.11% for PM0.3, a pressure drop of 42.2 Pa, and a quality factor of 0.112 Pa−1.

Cost and shelf life advantages:

Compared with commonly used corn protein, the cost of EC is only 12.77%, and the shelf life of its solution is extended by 50%, showing higher cost-effectiveness and practicality.

Summary

In this study, for the first time, green electrospinning was used to prepare ECM bimodal fiber membranes with good air filtration performance. The filtration efficiency was 99.11%, the pressure drop was 42.2 Pa, and the QF was 0.112 Pa−1. The electrospinning results of three molecular weight ECs: ECS, ECM, and ECL in ethanol and aqueous solution were compared, and a "solvent invasion control strategy" for preparing bimodal fibers was proposed. The key is to appropriately increase the molecular weight of the polymer and the concentration of the polymer solution so that the difference in the degree of stretching of the polymer chain in the solution can be amplified, and the viscosity force has a significant difference at the microscopic level, which promotes the formation of a bimodal structure. The solvent invasion of ECM is the most uneven, which is conducive to the formation of bimodal fibers. Compared with zein (the most commonly used bio-based material in green electrospinning), ECM solution has better electrospinning properties. On the other hand, the ECM fiber membrane has good hydrophobicity and mechanical properties, with a water contact angle of 129.30°, elastic modulus, tensile strength, and elongation at break of 20.69 MPa, 0.89 MPa, and 16.83%, respectively. In addition, the price of ECM is only 12.77% of the price of corn protein at 26.79 yuan. The shelf life of ECM is 12 h, which is 50% longer than that of corn protein (8 h), and has great potential for industrial and commercial production. This study will contribute to the development of green electrospun bio-based air filtration membranes.