Melt electrowriting of poly(vinylidene difluoride) using a heated collector

Abstract

Previous research on the melt electrowriting (MEW) of poly(vinylidene difluoride) (PVDF) resulted in electroactive fibers, however, printing more than five layers is challenging. Here, we investigate the influence of a heated collector to adjust the solidification rate of the PVDF jet so that it adheres sufficiently to each layer. A collector temperature of 110 C is required to improve fiber processing, resulting in a total of 20 fiber layers. For higher temperatures and higher layers, an interesting phenomenon occurred, where the intersection points of the fibers coalesced into periodic spheres of diameter 206 ± 52 μm (26G, 150 C collector temperature, 2000 mm/min, 10 layers in x-and y-direction).The heated collector is an important component of a MEW printer that allows polymers with a high melting point to be processable with increased layers.

The Impact of Including Carbonyl Iron Particles on the Melt Electrowriting Process

“…In addition, the warping of printed constructs was visible for all materials (Video S1, Supporting Information) affecting the printing process and resulting in limited layer stacking, as previously mentioned and observed for PVDF. [18,19] With increasing amount of particles, more particles were visible on the fiber morphology as shown in Figure 2. Even though the particles appeared mostly homogenously dispersed within the PVDF matrix, the blends with 5 wt% or more CI also showed domains with agglomerated particles.…”

“…Increasing the speed reduced this fiber pulsing phenomenon. As previously described when MEW‐processing PVDF [ 18,19 ] and its copolymer, [ 42 ] the rapid solidification of these materials during the printing process can lead to limited adherence onto the collector, as well as reduced fiber stacking and warping of the printed constructs.…”

“…In addition, the warping of printed constructs was visible for all materials (Video S1, Supporting Information) affecting the printing process and resulting in limited layer stacking, as previously mentioned and observed for PVDF. [ 18,19 ]…”

“…After poly(ɛ‐caprolactone) (PCL), PVDF is the most commonly MEW‐processed polymer [ 18,19 ] but has not yet been combined with filler particles. While particles of hydroxyapatite (HAp), [ 20 ] strontium‐substituted bioactive glass (SrBG), [ 21 ] bioactive milk proteins, lactoferrin, whey protein, [ 22 ] or reduced graphene oxide (rGO) [ 23 ] have been combined with PCL, particles with magnetic capacity such as carbonyl iron (CI) have not previously been studied for MEW.…”

3D Printed Tubular Scaffolds with Massively Tailorable Mechanical Behavior

“…At the junction, some fiber separation is observed; this is a common phenomenon in MEW scaffolds. [ 31 ] Each fiber had a roughly circular cross section with a mean diameter of 21.6 μm, resulting in a total thread height of 216 μm. Idealizing the thread cross section as a rectangle, the idealized thread area was 4666 μm 2 (see Section S1, Supporting Information).…”