Electrospining Machine: Core-sheath fibers prepared by single-nozzle spinning electrospun emulsion and homogeneous mixed solution

Background

Electrospinning is a versatile electrohydrodynamic process for the preparation of continuous microfibers and Electrospun Nanofbers by applying an electric field to a polymer solution or melt.The preparation of continuous defect-free fibers depends on the molar mass and concentration of the polymer exceeding a certain critical value. This ensures that the necessary conditions for fiber formation are met, i.e., effective entanglement of the polymer chains in the spinning solution or melt. In cases where these conditions are not met, i.e., where the molar mass or polymer concentration is below a specified limit, fibers are not formed. However, micro or nanoparticles are produced. This electrohydrodynamic process is known as electrospray. Studies on the suitability of electrospun nonwoven textiles have shown that these materials have potential for applications in a number of fields, including biomedicine, filtration and separation, design of protective clothing and sensors, agriculture, food packaging and preservation, and nanoelectronics.

The main point of this paper

Introduction to electrospinning technology:

Electrospinning is a technology that uses a high-voltage electric field to generate an electric force that excites the Taylor cone of a nozzle to form a jet stream and ultimately obtain nanofibers. This technique can produce fibers with diameters ranging from microns to tens of nanometers, showing unique and complex morphology . It is considered to be one of the most convenient, direct and economical methods to produce nanofibers, and many polymer solutions and melts can be used as raw materials to produce nanofibers.

Conventional electrospinning equipment:

Typical electrospinning equipment consists of a high-pressure source, a pump to maintain the solution flow rate, and a syringe equipped with a single-nozzle spinneret and a rotating drum collector.

In conventional single nozzle spinneret electrostatic spinning, a number of feed solutions are fed simultaneously through a series of single nozzle spinnerets, and the resulting fibers are subsequently deposited on a common collector.

Needle-free electrospinning technology:

The development of needleless electrospinning technology has led to significant advances in the production of nonwovens. It involves the electrostatic spinning of polymers directly from an open liquid surface. This technology is currently being commercialized by Elmarco s.r.o (Liberec, Czech Republic) under the brand name “Nano Spider”.

Needle-free electrospinning is a spinning method that utilizes a high-voltage electric field to create a spontaneous jet on the surface of a free liquid. The main device improvement is the spinneret (i.e., the liquid storage device).

Multi-nozzle spinneret electrospinning:

In order to improve the productivity of the electrospinning process, the electrostatic spinning equipment for a number of improvements to make multi-jet electrostatic spinning possible. In multi-nozzle spinneret electrostatic spinning, a number of feed solutions are fed simultaneously through a series of single-nozzle spinnerets, and the resulting fibers are then deposited on a common collector

Application and progress of electrospinning technology in the preparation of composite fibers with core-sheath structure

Importance:

Preparation of composite fibers with different core-sheath functions is an important topic in electrospinning technology.

Core-sheath fiber preparation method:

Coaxial electrospinning technology: requires coaxial spinnerets and immiscible internal and external solutions.

Emulsion electrospinning: uses a single nozzle spinneret and requires stabilizers.

Homogeneous Mixed Solution Electrospinning: Avoids the difficulties of coaxial and emulsion electrospinning by performing single nozzle electrospinning of two polymers or a mixed solution of polymers/low molecular weight substances.

Mechanism of core-sheath fiber formation:

The formation of core-sheath fibers is attributed to self-organization phenomena driven by phase separation during electrospinning.

Core-sheath fiber variants:

Core-double sheath fibers can also be obtained by the same method.

Potential Applications:

Potential applications for the preparation of core-sheath fibers by single-nozzle electrospinning of emulsions and homogeneous mixed solutions are discussed.

Application of low molecular weight substances or nanoscale inorganic additives:

Low molecular weight substances or nanoscale inorganic additives can be targeted for deposition in the core or sheath.

Summarize

Core-sheath fibers prepared from homogeneous co-mingled solutions by single nozzle spinneret electrospinning Single nozzle spinneret electrospinning of homogeneous co-mingled solutions is easy to apply as a prerequisite for industrial applications in the production of core-sheath fibers, e.g. by needleless or multi-nozzle electrospinning. Another advantage is the absence of stabilizers that are harmful to humans and the environment. This makes fiber materials prepared from single nozzle spinneret electrostatic spinning homogeneous blended solutions ecologically and biologically friendly for a variety of applications such as biomedical practices, food packaging and preservation, and green agriculture. With regard to the functionalization of fiber surfaces obtained by electrostatic spinning, it is of great interest to explore the potential for the formation of sheaths from non-electrospinnable polyelectrolytes of natural origin (e.g., chitosan, hyaluronic acid, and SA) as well as polyelectrolytes of synthetic origin with intrinsic bioactivity. As mentioned previously, single nozzle spinneret electrostatic spinning of homogeneous mixed solutions is a suitable and easily feasible method to achieve this desired result. Future directions in the field of single nozzle spinneret electrostatic spinning of homogeneous co-mingled solutions for the preparation of core-sheath fibers should seek to gain a deeper understanding of the factors that control the formation of fibers of this structure. It would also be of interest to expand research on the application of fibers obtained using this method.