Effect of the Fiber Diameter of Polyamide 11 Nanofibers on Their Internal Molecular Orientation and Properties

Herein, the effect of the diameter of polyamide 11 nanofibers (PA11 NFs) on their internal structures as well as thermal and mechanical properties is investigated. Aligned PA11 NFs with diameters ranging from 109 to 462 nm are prepared by the single-component solvent electrospinning of different PA11/1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) solutions (4-8 wt%) and subsequently characterized. Owing to the similar hydrogen bond formation within the NFs during electrospinning, all prepared NFs have delta'-phase crystals with similar crystallinities and crystallite sizes. However, the orientation of the delta'-phase crystals is disrupted in NFs with diameters less than 200 nm, due to the rapid solidification during electrospinning. The delta'-phase crystals are the most highly oriented within NFs having a fiber diameter of approximate to 300 nm, and the corresponding NF sheets exhibit the highest mechanical strength. A single PA11 NF with a fiber diameter of approximate to 300 nm also exhibits a good piezoelectric response (piezoelectric coefficient d(33) = 2.1 pm V-1).

Automated summary

The effect of the diameter of PA11 NFs on their structures and properties was investigated. Aligned PA11 NFs with diameters ranging from 109 to 462 nm were prepared and characterized. All prepared NFs had similar crystallinities and crystallite sizes, but the orientation of the crystals was disrupted in NFs with diameters less than 200 nm. The NFs with a diameter of approximately 300 nm had the most highly oriented crystals and exhibited the highest mechanical strength and piezoelectric response.