Impact of the Fiber Length Distribution on Porous Sponges Originating from Short Electrospun Fibers Made from Polymer Yarn

Abstract

Recently, the potential of electrospun fibers was reported for the fabrication of novel electrospun fibrous sponges by the use of short electrospun fibers. [4,6,14,16] Owing to flexible fabrication conditions and diversified electrospun fibers, the sponges displayed tunable densities, multifunctionality, and applicability for various applications, for instance, reversible manual compression, [16] hydrophilic or super hydrophobic, [17,18] electrics, [19,20] respirable open cells, [21] or scaffolds for tissue engineering. [22,23] Thus, these sponges could perfectly overcome the mechanical brittleness of traditional inorganic aerogel and high cost of carbon aerogel problems, making them a perfect candidate for broad applications due to their high potential for functionalization.So far, almost all the concepts to obtain ultralight sponges consist of fabrication of short electrospun fiber suspensions by mechanical cutting and processing by self-assembly, followed by freeze-drying. [10] Normally, the short fibers obtained by using mechanical cutting devices, such as homogenizer, mixer, blender, grinder, exhibit uncontrollable length and broad length distribution represented by the high coefficient of variation (CV), [3,[24][25][26] which is defined as the ratio of the standard deviation to the mean length. Simultaneously, beyond several different reported methods, such as chemical treatment, [27] ultrasonication, [28] electric spark, [29] concentrated polymer brush, [30] and direct electrospinning, [31][32][33] the patterned UV-crosslinking [34] and microcutting method [35,36] based on highly aligned fibers enable the production of quasi-monodisperse short fibers. Short fiber dispersions with low CV have not been used to the best of our knowledge for the preparation of sponges. Consequently, the role of CV and fiber length in the morphology and mechanical properties of the sponges is unknown, which is, however, very important for basic understanding and numerous applications.Herein, we present a new method for the preparation of short electrospun fiber dispersions with controlled CV and use them for the preparation of the sponges in order to evaluate the microstructure and mechanical properties. We show the cryo-microcutting of multifibrillar highly oriented electrospun poly(acrylonitrile) (PAN) yarns which resulted finally in short individual PAN fibers of well-controlled length. Fiber dispersions of different CVs were obtained by mixing of short fibers of different lengths, which were used for the preparation of sponges following the established method. We could clearly Ultralight highly porous sponges made of short electrospun polymer fibers have gained significant attention for a variety of applications. According to the established procedures, short electrospun fibers are obtained by cutting or homogenization of electrospun fibers in suspension, which yield fibers with inhomogeneous fiber length. The role of the fiber length distribution and the fiber length in the mechanical compressibility of the sponges is unkn...

Anisotropic Microparticles through Periodic Autofragmentation of Amphiphilic Triblock Copolymer Microfibers

“…Such controlled segmentation is particularly interesting in the case of polymeric fibers of microscale diameters, where the segmentation can lead to the formation of mesoscale anisotropic particles and short fibers. Such elongated particles are of interest for a range of applications, including drug delivery, − phagocytosis of particles by macrophages, − the formation of Pickering emulsions, and the construction of polymer sponges and aerogels. , Furthermore, the mechanism and properties that affect and control such processes, which are well rooted at the molecular level, might be easier to identify and interpret due to the relatively simpler configuration of 1D systems.…”

“…Such elongated particles are of interest for a range of applications, including drug delivery, 26−28 phagocytosis of particles by macrophages, 29−31 the formation of Pickering emulsions, 32 and the construction of polymer sponges and aerogels. 33,34 Furthermore, the mechanism and properties that affect and control such processes, which are well rooted at the molecular level, might be easier to identify and interpret due to the relatively simpler configuration of 1D systems.…”

Synthesis, Optimal Fabrication, and Physico‐Mechanical Property Evaluation of PCL‐b‐PLLA Diblock Copolymer‐Based Nanoscale Roughness Textured Electrospun Mats

“…has drawn significant attention. [1][2][3][4][5][6][7][8][9][10] The versatility of solution electrospinning lies in its ability to produce electrospun fibers with different orientation and morphology by varying process parameters (applied voltage, receiving distance, collector type, collector speed, orifice diameter tissue engineering and biomedical applications. [38][39][40][41][42][43][44][45] The morphology, thermal, microstructural, mechanical, and viscoelastic properties of different PLA/PCL blend-based EMs have been reported in our previous studies.…”

“…has drawn significant attention. [ 1–10 ] The versatility of solution electrospinning lies in its ability to produce electrospun fibers with different orientation and morphology by varying process parameters (applied voltage, receiving distance, collector type, collector speed, orifice diameter of needle and flow rate); electrospinning solution properties (viscosity, solvent volatility, electrical conductivity, and surface tension) and ambient conditions (temperature and humidity). [ 11 ] Further, the porous, interwoven, and continuous morphology of EMs contribute to its structural analogy with the extracellular matrix of indigenous tissues and thus act as potential candidates for the fabrication of devices for various biomedical applications such as tissue engineering, drug delivery, etc.…”

High-density Fibrous Polyimide Sponges with Superior Mechanical and Thermal Properties

“…Three-dimensional (3D) fibrous sponges made from electrospun fibers with superior mechanical and other properties have attracted increasing attention because of their superior characteristics, such as an interconnected network, light weight, low density, high porosity, hierarchical pore distribution, various material sources, and the ease with which they can be modified. − These properties have resulted in 3D fibrous sponges being broadly applied in, for example, solvent absorption, cell culture, oil/water separation, thermal insulation and sound insulation, and as drug carriers and catalyst supports. − However, most of these 3D sponges possess relatively weak mechanical properties. Our recent report showed that the polyacrylate-based fibrous sponges exhibited a weak compressive strength <1 kPa .…”