Electrospun fiber deposition using the gap method alters fiber moduli*

Applications of electrospun nanofibers often require precise mechanical properties and fiber deposition. One common way to control fiber deposition is to use parallel collectors separated by a gap (gap method). In this work, we investigate the effect of gap method deposition on fiber modulus.

We formed electrospun fibers using collectors spaced at various gaps ranging from 2 cm to 10 cm and fiber moduli were measured by AFM using 3-point bending.

The gap between the collector plates had an inverse relationship with the diameter of the fibers; larger gaps produced smaller fibers. In agreement with previous data, the small fibers created by the larger gap distance had higher average moduli (67 +/- 9 GPa for a 10 cm gap) than larger fibers (10 +/- 2 GPa for a 4 cm gap). Therefore, fiber deposition directly influenced individual fiber moduli.
Additionally, when we compared fibers of similar diameter we found larger gap distances produces fibers with higher moduli independent of fiber diameter. Fibers with diameters between 150 nm and 250 nm had an average modulus of 18 +/- 3 GPa for an 8 cm gap and 12 +/- 2 GPa for a 4 cm gap. Preliminary data using polarized-FTIR suggest molecular alignment is increased by the gap method.