# Mechanical Properties of Dual-Layer Electrospun Fiber Mats

## TL;DR

This paper shows how layering different materials in electrospun mats can significantly enhance their mechanical properties, such as stiffness, while keeping flexibility.

## Contribution

The study demonstrates a 60-fold increase in Young’s modulus using dual-layer electrospun mats of TPU and nylon.

## Key findings

- Layering TPU with nylon increased Young’s modulus by 60-fold.
- The Young’s modulus was predicted by the Voigt rule of mixtures.
- Elongation at break was determined by the stiffer material, not its volume fraction.

## Abstract

Electrospinning with sequential layer deposition has been reported for various applications such as tissue scaffolds, shape memory materials, and separations. However, the effect of layering on the mechanical properties is not fully understood. In this work, layered structures of thermoplastic polyurethane (TPU) and nylon were selected as a model system to investigate the effect of sequential layer deposition on mechanical properties. Evidence of the layered structure was indicated by scanning electron microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR) experiments. Layering TPU with nylon resulted in a 60-fold increase in the Young’s modulus. The Young’s modulus of the layered structure was reasonably predicted by the Voigt rule of mixtures. Furthermore, the Young’s modulus changes without any statistically significant change in elongation at break compared to a single layer of nylon. Thus, the elongation at break was dictated by the stiffer material, despite being present at a lower volume fraction. Overall, electrospinning with sequential layer deposition electrospinning is an effective approach for tuning the mechanical properties and surface chemistry of electrospun materials independently, which may be of interest for applications in tissue engineering and separations.