Fabricating Fibers of a Porous-Polystyrene Shell and Particle-Loaded Core

Adv Materials Technologies

et al. 2020

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portable chemiresistive devices based on the resistance change of metal oxide semiconductors upon absorbing VOCs. [8-14] In particular, when nanostructured, their detection capabilities to analytes could reach down to a few parts per billion (ppb) and with good response time. [15] Thus, they are ideal for important biological applications, such as breath and respiratory diagnostics. [16] Their high sensitivities are nevertheless coupled with elevated operating temperatures, usually several hundred degrees Celsius as well as low thermal stability under various environments. [17-19] This limits their application in multifunctional devices, especially due to the low survivability of the rigid metaloxide devices under complex dynamic or fatigue conditions. On the other hand, conductive polymer nanoparticle composites have demonstrated stable performances under extreme conditions, [20] can be scalably manufactured, [21-23] and meet compliance requirements of wearable electronics. [24,25] Their gas sensing functionalities, based on the Flory-Huggins interaction parameters between solvents and polymers, have also been investigated with various polymer matrices and nanoparticles. [26-30] Currently, the main performance-limiting factor is their low sensitivity, usually in the range of several parts per thousand to a few hundred parts per million (ppm). Increasing the surface area is one of the most efficient methods to increase sensitivity, such as in macroscale helical structure, [31] microscale scaffolds, [32] and nanoscale nanofibers. [33] Notably, nature provides inspirations that have unparalleled advantages in material design and fabrication. [34-37] Herein, we introduce a multilayered, porous, and hollow fiber sensor with enhanced functionalities mimicking the metaxylem structure of vascular plants (Figure 1a). Vascular plants utilize metaxylem conduits for the transpiration and transport of water and minerals from the ground to the leaves. In the presence of nutrient scarcity, transpiration efficiency is enhanced as pits on the cell wall facilitate the horizontal diffusion of water and minerals into adjacent cells. [38] Inspired by this highly ordered pit structure, we developed a multilayered polymer nanoparticle sensor with a self-induced hollow core that increases the surface area in macro-and microscales, with VOC sensitivity up to 15 ppm for xylene, There are advantages to polymer/nanoparticle composite-based volatile organic compounds (VOCs) sensors, such as high chemical and physical stability, operability under extreme conditions, flexible use in manufacturing, and low cost. Nevertheless, their lower limit of detection due to thickness-dependent diffusion has constrained their application. Inspired by the metaxylem in vascular plants and its vertical conduits and horizontal pits that enable efficient transpiration, a polymer/nanoparticle compositebased sensor is fabricated with a controllable, spontaneously formed, hollow core for inline VOCs transportation, and porous microstructure for radial direction d...

Section: Resultsmentioning

confidence: 99%

Bioinspired, Mechanically Robust Chemiresistor for Inline Volatile Organic Compounds Sensing

Adv Materials Technologies

et al. 2020

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“…The use of porogens is one of the most common methods, and the porogen types can be primarily divided into solid, 44,45 gaseous, 46 solvent, [47][48][49] ionic liquid 50 and oligomeric porogen. 51 Through further etching, washing or evaporating, porous structures can be obtained. For example, Anikeeva and her group have premixed filtered salt with polycaprolactone (PCL) for thermal fiber drawing.…”

Section: Fiber Microstructures Porousmentioning

confidence: 99%

“…Table 1 lists some recent work on porous fibers with associated applications and fabrication methods. The use of porogens is one of the most common methods, and the porogen types can be primarily divided into solid, 44,45 gaseous, 46 solvent, 47–49 ionic liquid 50 and oligomeric porogen 51 . Through further etching, washing or evaporating, porous structures can be obtained.…”

Section: Fiber Microstructuresmentioning

confidence: 99%

A mini‐review of microstructural control during composite fiber spinning

et al. 2022

Polymer International

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From wool to Kevlar, one‐dimensional (1D) fiber has experienced the transition from clothing materials to structural applications in the past centuries. However, the recent advancements in tooling engineering and manufacturing processes have attracted much attention from both academia and industry to fabricate novel, versatile fibers with unique microstructures and unprecedented properties. This mini‐review focuses on the fabrication techniques of porous, coaxial, layer‐by‐layer and segmented fibers with continuous solution and melt fiber spinning methods. In each section of this review article, the unique structure‐related applications, including intelligent devices, healthcare devices, energy storage systems, wearable electronics and sustainable products, are discussed and evaluated. Finally, the combination of additive manufacturing for 1D fiber patterning in two‐dimensional and three‐dimensional devices, in addition to challenges in the reviewed fiber microstructures, is briefly introduced in the conclusion. © 2021 Society of Industrial Chemistry.

“…For example, fiber spinning can leverage mechanical drawing to align nanoparticles along thindiameter fibers along the fiber axis. [90,102,301,302,306,308,309,490,[539][540][541][542] However, the fabrication of 3D structures via 1D fibers involves spinning, drawing, knitting, stacking, pressing, or weaving (Figure 8a-f). Besides, the inclu sion of nanoparticles at selective locations may require expen sive tooling engineering, e.g., embedding nanoparticles between polymer layers requires a redesign of the spinning apparatus (Figure 25a 1 -a 4 ).…”

Section: Prospects Of Challenges and Opportunitiesmentioning

confidence: 99%

3D Printing‐Enabled Nanoparticle Alignment: A Review of Mechanisms and Applications

et al. 2021

Small

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3D printing (additive manufacturing (AM)) has enormous potential for rapid tooling and mass production due to its design flexibility and significant reduction of the timeline from design to manufacturing. The current state-of-the-art in 3D printing focuses on material manufacturability and engineering applications. However, there still exists the bottleneck of low printing resolution and processing rates, especially when nanomaterials need tailorable orders at different scales. An interesting phenomenon is the preferential alignment of nanoparticles that enhance material properties. Therefore, this review emphasizes the landscape of nanoparticle alignment in the context of 3D printing. Herein, a brief overview of 3D printing is provided, followed by a comprehensive summary of the 3D printing-enabled nanoparticle alignment in wellestablished and in-house customized 3D printing mechanisms that can lead to selective deposition and preferential orientation of nanoparticles. Subsequently, it is listed that typical applications that utilized the properties of ordered nanoparticles (e.g., structural composites, heat conductors, chemo-resistive sensors, engineered surfaces, tissue scaffolds, and actuators based on structural and functional property improvement). This review's emphasis is on the particle alignment methodology and the performance of composites incorporating aligned nanoparticles. In the end, significant limitations of current 3D printing techniques are identified together with future perspectives.