Wetting and aging behaviors for several O₂ and NH₃ plasma treated nanofibrous and flat film polymer materials: A comparison

Abstract

Aging (or "hydrophobic recovery") of plasma-modified polymer surfaces has been known and documented in the literature over several decades; to the best of our knowledge, the present study appears to be the first in which this is done for two vastly different rough surface structures: (i) electrospun nanofibrous (NF) mats, and (ii) flat films (FF), for three polymers of well-documented interest in biotechnological applications: poly(lactic acid); poly(urethane); and poly(caprolactone). Two different plasma treatments are applied: low-pressure (LP) radiofrequency (rf) glow discharges in flows of O 2 and NH 3 under mild power conditions. Measured time-dependent surface compositions (from X-ray photoelectron spectroscopy survey spectra) and water contact angles (WCA) were found to tend toward asymptotic limiting values after ca. 30 days of storage in clean air, as previously reported by these and other authors. An entirely novel aspect of this work is to examine and compare time-dependent WCA behaviors of NF and FF samples in terms of Wenzel (W)

Plasma Surface Treatment and Application of Polyvinyl Alcohol/Polylactic Acid Electrospun Fibrous Hemostatic Membrane

“…Moreover, the 5 min-treated PVA fibrous membrane shows much faster spreading of droplets than the untreated fibrous membrane, and droplets on 5 min-treated PVA fibrous membrane spread out in less than 8 s. In addition, the moisture absorption experiment proves that the fiber membrane with plasma treatment of 5 min has a faster moisture absorption speed in the early stages. The mesh structure of the fibrous membrane and the roughness, content of polar functional groups, and fiber fraction of fiber surface are the major influencing factors on fibrous membrane wettability [ 39 , 40 , 41 , 42 , 43 , 44 ]. Before plasma treatment, a large contact angle attributed to the meshes maintains the entrapped air between fibers, decreasing the surface free energy of the PVA fiber membrane.…”