TY  - JOUR
A1  - Sauter, Tilman
A1  - Kratz, Karl
A1  - Heuchel, Matthias
A1  - Lendlein, Andreas
T1  - Fiber diameter as design parameter for tailoring the macroscopic shape-memory performance of electrospun meshes
JF  - Materials and design
N2  - Fibrous shape-memory polymer (SMP) scaffolds were investigated considering the fiber as basic microstructural feature. By reduction of the fiber diameter in randomly oriented electrospun polyetherurethane (PEU) meshes from the micro-to the nano-scale, we observed changes in the molecular orientation within the fibers and its impact on the structural and shape-memory performance. It was assumed that a spatial restriction by reduction of the fiber diameter increases molecular orientation along the orientation of the fiber. The stress-strain relation of random PEU scaffolds is initially determined by the 3D arrangement of the fibers and thus is independent of the molecular orientation. Increasing the molecular orientation with decreasing single fiber diameter in scaffolds composed of randomly arranged fibers did not alter the initial stiffness and peak stress but strongly influenced the elongation at break and the stress increase above the Yield point. Reduction of the single fiber diameter also distinctly improved the shape-memory performance of the scaffolds. Fibers with nanoscale diameters (< 100 nm) possessed an almost complete shape recovery, high recovery stresses and fast relaxation kinetics, while the shape fixity was found to decrease with decreasing fiber diameter. Hence, the fiber diameter is a relevant design parameter for SMP.
KW  - Nanofiber
KW  - Shape-memory polymer
KW  - Electrospinning
KW  - Function by design
KW  - Molecular orientation
Y1  - 2021
U6  - https://doi.org/10.1016/j.matdes.2021.109546
SN  - 1873-4197
VL  - 202
PB  - Elsevier
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Bagdahn, Christian
A1  - Taubert, Andreas
T1  - Ionogel fiber mats - functional materials via electrospinning of PMMA and the ionic liquid bis(1-butyl-3-methyl-imidazolium) Tetrachloridocuprate(II), [Bmim](2)[CuCl4]
JF  - Zeitschrift für Naturforschung : B, Chemical sciences
N2  - Ionogel fiber mats were made by electrospinning poly(methylmethacrylate) (PMMA) and the ionic liquid (IL) bis(1-butyl-3-methyl-imidazolium) tetrachloridocupraten, [Bmim](2)[CuCl4], from acetone. The morphology of the electrospun ionogels strongly depends on the spinning parameters. Dense and uniform fiber mats were only obtained at concentrations of 60 to 70 g of polymer and IL mass combined. Lower concentrations led to a low number of poorly defined fibers. High voltages of 20 to 25 kV led to well-defined and uniform fibers; voltages between 15 and 20 kV again led to less uniform and less dense fibers. At 10 kV and lower, no spinning could be induced. Finally, PMMA fibers electrospun without IL show a less well-defined morphology combining fibers and oblong droplets indicating that the IL has a beneficial effect on the electrospinning process. The resulting materials are prototypes for new functional materials, for example in sterile filtration.
KW  - Ionic Liquid
KW  - Ionogel
KW  - Electrospinning
KW  - Fiber
KW  - Hydrogen Production
KW  - Filtration
Y1  - 2013
U6  - https://doi.org/10.5560/ZNB.2013-3195
SN  - 0932-0776
SN  - 1865-7117
VL  - 68
IS  - 10
SP  - 1163
EP  - 1171
PB  - De Gruyter
CY  - Tübingen
ER  -