In situ syringe rotation system for heavy microparticle suspension stability in electrospinning technique

Electrospinning allows the fabrication of polymeric nonwovens with a wide variety of inclusions in the micro-nanofibers. However, the electrospinning of microparticle-filled polymer solutions is still limited in particle size, density, and concentration, mainly due to suspension instability during the electrospinning process, so it is not commonly investigated despite the vast number of possible applications. In this study, a simple and effective novel rotation device was developed to prevent the settling of microparticles in the polymer solution during electrospinning. The stability of polyvinyl alcohol and polyvinylidene fluoride (PVDF) solutions with indium microparticles (IMPs) of (42 ± 7) μm diameter was evaluated using LASER transmittance inside a syringe, both static and rotating for 24 h. While the static suspensions completely settled at 7 min and 9 h, respectively, depending on solution viscosity, the rotating suspensions remained stable throughout the experiment. The number and distribution of IMPs in PVDF electrospun mats were determined by optic microscopy and a novel x-ray imaging mapping method, showing 165% more IMPs in the mat obtained with the rotating syringe device. A simple analysis of the theoretical background of settling and rotating suspensions was included to understand the working mechanism of the device. Also, the electrospinning of solutions with high loadings of IMPs (up to 400% w/w PVDF) was accomplished. The simplicity and outstanding efficiency of the device shown in this work may serve as a solution to technical difficulties and as an encouragement to future research in microparticle-filled solution electrospinning.