Coaxial Electrospinning
“An interesting variation of electrospinning is the use of a spinneret comprising two coaxial capillaries, allowing two different liquids to be spun, one inside the other, leading to a composite fibre with core–sheath structure. Recently it could be shown that also a room temperature nematic liquid crystal (LC) can be coaxially spun with a composite sheath of TiO2 and poly(vinylpyrrolidone) (PVP). Such composite fibres with a core exhibiting the responsiveness and special properties (in particular optical) that result from the unique combination of fluidity and long-range order of liquid crystals are interesting from different points of view. On the one hand, the LC can give the fibre new functionality, in particular sensitivity to temperature variations or to the application of electric and/or magnetic fields, on the other the strong confinement that can be achieved by the process can affect the LC phase sequence. Electrospinning offers a cheap and simple way of studying such confinement effects systematically.".
(Enz, Baumeister and Lagerwall, Beilstein Journal of Organic Chemistry, 2009)
Recent Journal Articles
One-Step Fabrication of Multifunctional Core-Shell Fibres by Co-Electrospinning
(3488–3495)Advanced Functional Materials 21 #18 (2011)
Medina-Castillo, Fernández-Sánchez and Fernández-Gutiérrez of the University of Granada and NanoMyP, Nanomateriales y Polimeros, Spain, produced multifunctional core-shell fibre mats by co-electrospinning. These core-shell fibre mats have three different functionalities: 1) they are magnetic, 2) they change their optical properties with the pH of the media, and 3) they are sensitive to O2. The shell is formed by a fluorescent pH-sensitive co-polymer. The core is a suspension formed by magnetic nanoparticles in a solution made up by a lipophilic indicator dye (oxygen indicator; PtOEP) and, poly-methyl methacrylate, in THF. The magnetic nanoparticles were prepared by encapsulation of magnetite within a cross-linked polymeric matrix (MMA-co-EDMA). (RDC 9/20/2011)
Improving Polymer Nanofiber Quality Using a Modified Co-axial Electrospinning Process
(744–750)Macromolecular Rapid Communications 32 #9-10 (2011)
Yu et al of Donghua University, China and London Metropolitan University, United Kingdom, developed a new strategy for systematically improving polymer nanofiber quality based on a modified coaxial electrospinning process and suitable selection of solvent mixtures as sheath fluid. A concentric spinneret with an indented inner capillary is designed for the modified coaxial electrospinning. With a solution of 12% w/v PVP K60 in ethanol as the core electrospinning fluid, six solvents are used as sheath fluids to investigate the impact of solvent properties on the resultant PVP nanofiber quality. The PVP nanofiber quality is closely related to solvent physical-chemical properties. High quality PVP nanofibers of average diameter 130 ±10 nm with homogeneous structures and smooth surfaces are created using a solvent mixture of acetone, ethanol and DMAc in the ratio of 3:1:1(v/v/v). (RDC 5/26/2011)
Reversibly thermochromic micro-fibres by coaxial electrospinning
(5037-5043) Polymer 51 #22 (2010)
Matherbe et al of the University of Stellenbosch, South Africa used a ‘solvent facilitated’ coaxial electrospinning process to produce reversible narrow temperature gap thermochromic, core-shell fibres. A thermochromic composite composed of crystal violet lactone (the leuco dye), bisphenol A (the developer) and 1-dodecanol (the phase-change solvent) was entrained as core material inside poly(methyl methacrylate) shells. A mutual core and shell solvent (chloroform) was used to obtain low interfacial tension between the core and shell spinning solutions. (RDC 12/17/2010)