UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi

Abstract

Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU) are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae, when the films were pre-treated with Ultraviolet (UV) irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR), scanning electron microscopy (SEM), and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

Enhanced glycerol dehydration of pervaporation cross‐linkedPVAmembranes modified byVUV/UV‐Ctreatments

“…Previous studies have shown the benefits of using AA vapors in plasma treatments to increase the PV performance of the membranes 31,32 and UV‐assisted treatments to induce biodegradation processes in polymers 34 . In those reports, for example, it was verified that a typical result of the UV‐assisted treatments in the presence of AA vapors on polymers was the polymerization of a poly(acrylic acid) (PAA) like film on top of the untreated film 43 .…”

“…VUV 36 and UV 34,37,43 irradiation was carried out following a methodology already published. Briefly, a Deuterium almost monochromatic source (162 nm) of 140 W (Hamamatsu, Japan) fitted in a homemade stainless steel photochemical reactor was used as a VUV source.…”

“…[34][35][36] In many cases, the typical thermodynamic aging recovery of the original surface properties, that is usually observed with traditional plasma treatments, were not observed with UV or VUV treatments. 34,36 Additionally, in some case studies, a comparison between UVassisted treatments of polysulfone films and low-pressure radio frequency plasma treatments showed similar degrees of hydrophilic surface conversion. 37 Surface photo-induced graft copolymerization methods have been studied in the past to modify the membrane surfaces with success; despite that, the use this technology was recently found to be very effective for the modification of polyethersulfone (PES) membranes for the separation of oil from wastewaters 16 and improvements in the permeability and antifouling performance of the poly (ether ether ketone) (PEEK) membranes.…”

“…More recently, our research group started to use electromagnetic radiation as a dry and simple tool to modify the surface of the polymer films. In addition to the simplicity of the technique, there is an important gain in the permanent surface properties obtained 34–36 . In many cases, the typical thermodynamic aging recovery of the original surface properties, that is usually observed with traditional plasma treatments, were not observed with UV or VUV treatments 34,36 .…”

“…In addition to the simplicity of the technique, there is an important gain in the permanent surface properties obtained 34–36 . In many cases, the typical thermodynamic aging recovery of the original surface properties, that is usually observed with traditional plasma treatments, were not observed with UV or VUV treatments 34,36 . Additionally, in some case studies, a comparison between UV‐assisted treatments of polysulfone films and low‐pressure radio frequency plasma treatments showed similar degrees of hydrophilic surface conversion 37 .…”