Electrospinning of Highly Crystalline Polymers for Strongly Oriented Fibers

Abstract

Electrospun nanofibers (NFs) often demonstrate an exponential increase in mechanical and other properties at reduced diameters. Molecular orientation emerges as a key parameter for the performance of amorphous and low crystallinity polymers, but single-fiber structural investigations are still lacking for highly crystalline polymers. Herein, polarized confocal Raman spectroscopy reveals that fibers of highly crystalline poly(ethylene oxide) (PEO) maintain a high orientation over a broad range of diameters, in strong contrast with the usual exponential trend. This observation stands for five electrospinning solvents of widely different properties. By comparison, poly(oxymethylene) (POM) NFs also show a high orientation at low diameters, but it decreases substantially for diameters larger than ∼1400 nm, a result attributed to the lower crystallinity of POM compared to that of PEO. The results show that the exponential orientation dependence on fiber diameter is not universal and stress the importance of polymer crystallinity on the structure and properties of electrospun nanofibers. This work guides the preparation of fibers with optimal orientationdependent properties and shows that high crystallinity can afford more robust materials whose performance is less affected by variations in experimental conditions, a valuable feature for most applications.

Structural Analysis of Injection-Molded Polyoxymethylene Treated Below a Melting Point Using Field-Emission Scanning Electron Microscopy and Infrared Spectroscopy

“…1–11 Some research has focused on morphology and crystal structures. 12–20 Previous work has established that POM has various structures and morphologies dependent on temperature, 15–17 pressure, 19 and manufacturing method. 20…”

“…[1][2][3][4][5][6][7][8][9][10][11] Some research has focused on morphology and crystal structures. [12][13][14][15][16][17][18][19][20] Previous work has established that POM has various structures and morphologies dependent on temperature, [15][16][17] pressure, 19 and manufacturing method. 20 It is well known that POM has a 9/5 or 29/16 helical trigonal crystal structure.…”

“…[12][13][14][15][16][17][18][19][20] Previous work has established that POM has various structures and morphologies dependent on temperature, [15][16][17] pressure, 19 and manufacturing method. 20 It is well known that POM has a 9/5 or 29/16 helical trigonal crystal structure. 1,2 In addition, it has been reported that the crystal form changes under high pressure from trigonal to orthorhombic.…”

Effect of PEO crystallization on dielectric response of PVDF/PEO@IL coaxial electrospinning nanofiber films

“…The epoxy vinyl (CH 2 CH 2 O) unit has a strong electron donating capacity, which is conducive to the dissociation of the salt. Moreover, due to the existence of a single CO and CC bonds in the PEO main chain, the PEO chain in the amorphous region can easily coordinate and recombine with the dissociated cations in the IL, which can effectively restrict the IL to the amorphous region of the PEO; 35–37 (2) Due to the strong electric field stretching force during the electrospinning process, the PEO in the coaxial fiber P/E@IL crystallizes and the c‐axis of PEO lamellae is supposed to be parallel to the stretching direction 38 . In this case, PEO crystals can confine the IL and PEO amorphous regions within an enclosed domain, which blocks the conduction path inside the IL fiber to suppress its tan δ; 39,40 (3) Moreover, the shell layer of PVDF can form a relatively confinement domain to enclose the IL and to avoid the leakage of ions.…”

High Piezoelectric Output Voltage from Blue Fluorescent N,N-Dimethyl-4-Nitroaniline Nano Crystals into Poly-L-Lactic Acid Electrospun Fibers

“…The technique experimental accessibility and versatility has enabled the preparation of nanomaterials from a remarkably broad class of macromolecular-based systems [24][25][26]. The functional properties of electrospun fibers are therefore determined by the chemical nature of electrospinning materials solutions, the different processing conditions as well the polymer crystallinity and its molecular orientation inside the micro/nanofibers [27][28]. The technique has been used as a method for producing aligned polymer doped micro/nanofibers with a high degree of guest molecular polar orientation within the polymer.…”