Long-term aging characteristics of atmospheric-plasma-treated poly(ɛ-caprolactone) films and fibres

This paper reports the change in the surface properties and aging behaviours of surface-modified poly(ɛ-caprolactone) films and nanofibres after atmospheric plasma treatment with a reactive gas. The morphologies, roughness, chemical bonding states, and surface energies of pristine and atmospheric-plasma-treated nanofibres were investigated. The nanofibres subjected to O2 atmospheric plasma treatment showed higher surface roughness (∼88%), fibre diameter (∼14%), surface energy (∼19.2 times), and hydrophilicity (O/C atomic ratio, ∼43%) than did the pristine nanofibres. Over a 6-month period, the characteristics of the nanofibres isolated from air were not significantly altered; however, in the case of the nanofibres exposed to air, there was a subsequent increase in the surface roughness (∼82%), fibre diameter (∼7%), surface energy (∼27%), and hydrophilicity (O/C atomic ratio, ∼17.6%). We confirmed that the properties of the atmospheric-plasma-treated poly(ɛ-caprolactone) nanofibres maintained for 6 months without exposure to air did not show any significant change. Consequently, these nanofibres would be well suited for biomedical applications that require long-term sample stability.