Nanovascularization of polymer matrix: generation of nanochannels and nanotubes by sacrificial electrospun fibres

A 3D interconnected vasculature in composite materials is desired for several uses (e.g. filtration, self-healing, self-cooling, bioengineering, chemical reactors). Known methods for creating vascular structures produce channels with millimetric or micrometric diameters, are time-consuming and scalable with difficulty. Here, we propose the use of sacrificial electrospun fibres to generate nanovascularized composites containing interconnected channels and tubes having sub-micrometric and nanometric diameters. Pullulan was chosen as sacrificial material since it is commercially available, soluble in water and it is thermally and morphologically stable up to 250°C. We show that the empty nanochannels created in a thermoset polymer matrix by dissolving pullulan fibres can be re-filled by a liquid substance. Moreover, by using core-shell electrospun nanofibres with a sacrificial core we created nanoubes with walls coated with a material that can impart additional functionality to the channels (e.g. remediation properties, release of active molecules, etc.). The proposed method can be realistically coupled with current composite manufacturing, thus widening possible applications of these kind of innovative materials that can potentially display new and enhanced functionalities thanks to the nanoscale features of the cavities.