Wettability of Electrospun Films of Microphase-Separated Block Copolymers with 3,3,3-Trifluoropropyl Substituted Siloxane Segments

Fluorinated polymers or chemicals with long length of fluorinated tail are often used to enhance the hydrophobicity and oleophobicity of surfaces. In this work, superhydrophobic and highly solvent-repellent surfaces were fabricated by using a series of block copolymers with 3,3,3-trifluoropropyl substituted siloxane segments via an electrospinning process. The contact angles of deionized water on the electrospun films are higher than 150° and the water roll-off angles are less than 10°, denoting a superhydrophobic property for the electrospun films. The electrospun films can also exhibit contact angles higher than 150° for glycerol, formamide, and diethylene glycol. Moreover, it is surprising to find that very high contact angles with small roll-off angles on the electrospun films could be obtained by using the oil liquids colored by 0.4 wt % oil-soluble dyes. By investigating the properties of the thin/electrospun films of block copolymers, it is found that the microphase-separation behavior of block copolymers could be an important reason for the formation of nanoscale surface roughness. The electrospun films can exhibit superhydrophobicity and high solvent resistance, owing to the formation of multiscale surface roughness as well as the surface segregation of low surface energy groups

Wettability of Electrospun Films of Microphase-Separated Block Copolymers with 3,3,3-Trifluoropropyl Substituted Siloxane Segments

Fluorinated polymers or chemicals with long length of fluorinated tail are often used to enhance the hydrophobicity and oleophobicity of surfaces. In this work, superhydrophobic and highly solvent-repellent surfaces were fabricated by using a series of block copolymers with 3,3,3-trifluoropropyl substituted siloxane segments via an electrospinning process. The contact angles of deionized water on the electrospun films are higher than 150° and the water roll-off angles are less than 10°, denoting a superhydrophobic property for the electrospun films. The electrospun films can also exhibit contact angles higher than 150° for glycerol, formamide, and diethylene glycol. Moreover, it is surprising to find that very high contact angles with small roll-off angles on the electrospun films could be obtained by using the oil liquids colored by 0.4 wt % oil-soluble dyes. By investigating the properties of the thin/electrospun films of block copolymers, it is found that the microphase-separation behavior of block copolymers could be an important reason for the formation of nanoscale surface roughness. The electrospun films can exhibit superhydrophobicity and high solvent resistance, owing to the formation of multiscale surface roughness as well as the surface segregation of low surface energy groups

Guidance on the Application of Polyurethane Foam Disk Passive Air Samplers for Measuring Nonane and Short-Chain Chlorinated Paraffins in Air: Results from a Screening Study in Urban Air

This study provides guidance on using polyurethane foam-based passive air samplers (PUF-PASs) for atmospheric nonane chlorinated paraffins (C9-CPs) and short-chain CPs (SCCPs) and reports SCCP concentrations in air in the Greater Toronto Area (GTA), Canada. We estimated the partition coefficients between PUF and air (KPUF‑A) and between octanol and air (KOA) for C9-CP and SCCP congeners using the COSMO-RS method, so that PUF disk uptake profiles for each formula group could be calculated. We then measured SCCP concentrations in PUF disk samples collected from distinct source sectors in urban air across the GTA. Concentrations in samplers were used to calculate C9-CP and SCCP concentrations in air and the PUF disk uptake profiles revealed that time-weighted linear phase sampling was possible for congeners having log KOA values greater than 8.5. The highest SCCP concentrations, with an annual average concentration of 35.3 ng/m3, were measured at the industrial site, whereas lower but comparable SCCP concentrations were found in residential and background sites, with annual averages of 7.73 and 10.5 ng/m3, respectively. No consistent seasonal variation in SCCP concentrations was found in the six distinct source sectors. Direct measurements of KPUF‑A and KOA values as a function of temperature could be used to increase accuracy in future studies

Guidance on the Application of Polyurethane Foam Disk Passive Air Samplers for Measuring Nonane and Short-Chain Chlorinated Paraffins in Air: Results from a Screening Study in Urban Air

This study provides guidance on using polyurethane foam-based passive air samplers (PUF-PASs) for atmospheric nonane chlorinated paraffins (C9-CPs) and short-chain CPs (SCCPs) and reports SCCP concentrations in air in the Greater Toronto Area (GTA), Canada. We estimated the partition coefficients between PUF and air (KPUF‑A) and between octanol and air (KOA) for C9-CP and SCCP congeners using the COSMO-RS method, so that PUF disk uptake profiles for each formula group could be calculated. We then measured SCCP concentrations in PUF disk samples collected from distinct source sectors in urban air across the GTA. Concentrations in samplers were used to calculate C9-CP and SCCP concentrations in air and the PUF disk uptake profiles revealed that time-weighted linear phase sampling was possible for congeners having log KOA values greater than 8.5. The highest SCCP concentrations, with an annual average concentration of 35.3 ng/m3, were measured at the industrial site, whereas lower but comparable SCCP concentrations were found in residential and background sites, with annual averages of 7.73 and 10.5 ng/m3, respectively. No consistent seasonal variation in SCCP concentrations was found in the six distinct source sectors. Direct measurements of KPUF‑A and KOA values as a function of temperature could be used to increase accuracy in future studies

Personal Wearable Sampler for Per- and Polyfluoroalkyl Substances Exposure Assessment

Per- and polyfluoroalkyl substances (PFAS) are ubiquitously detected in the environment, raising concerns about human exposure. The assessment of individual exposure to PFAS has been limited due to the lack of specialized sampling tools. Personal wearable samplers, including silicone wristbands, have been used for PFAS exposure assessment. However, translating data into human exposure has been challenging due to the lack of chemical sampling rates by those samplers. We developed and evaluated a personal air wearable sampler (PAWS) using sorbent-impregnated polyurethane foam for its ability to capture diverse PFAS. Simultaneously, we deployed silicone wristbands for comparison. Our results showed that the PAWS effectively captured both ionic and neutral PFAS, while silicone wristbands had relatively limited capacity for perfluorocarboxylic acids (PFCAs). Our observations suggest silicone wristbands may collect polyfluoroalkyl phosphoric acid diesters (diPAPs) through dermal contact, although further investigation is necessary. PFAS concentrations detected in the PAWS can be converted into concentrations in air by using previously established sampling rates, facilitating quantitative inhalation exposure assessment. Smoking status was found to be associated with high diPAP levels in both PAWS and silicone wristbands, although further validation is needed. The PAWS is a promising technology for application in personal exposure assessment for structurally diverse chemicals

Poly(pro-curcumin) Materials Exhibit Dual Release Rates and Prolonged Antioxidant Activity as Thin Films and Self-Assembled Particles

Curcumin is a natural polyphenol that exhibits remarkable antioxidant and anti-inflammatory activities; however, its clinical application is limited in part by its physiological instability. Here, we report the synthesis of curcumin-derived polyesters that release curcumin upon hydrolytic degradation to improve curcumin stability and solubility in physiological conditions. Curcumin was incorporated in the polymer backbone by a one-pot condensation polymerization in the presence of sebacoyl chloride and polyethylene glycol (PEG, Mn = 1 kDa). The thermal and mechanical properties, surface wettability, self-assembly behavior, and drug-release kinetics all depend sensitively on the mole percentage of curcumin incorporated in these statistical copolymers. Curcumin release was triggered by the hydrolysis of phenolic esters on the polymer backbone, which was confirmed using a PEGylated curcumin model compound, which represented a putative repeating unit within the polymer. The release rate of curcumin was controlled by the hydrophilicity of the polymers. Burst release (2 days) and extended release (>8 weeks) can be achieved from the same polymer depending on curcumin content in the copolymer. The materials can quench free radicals for at least 8 weeks and protect primary neurons from oxidative stress in vitro. Further, these copolymer materials could be processed into both thin films and self-assembled particles, depending on the solvent-based casting conditions. Finally, we envision that these materials may have potential for neural tissue engineering application, where antioxidant release can mitigate oxidative stress and the inflammatory response following neural injury

Virucidal N95 Respirator Face Masks via Ultrathin Surface-Grafted Quaternary Ammonium Polymer Coatings

N95 respirator face masks serve as effective physical barriers against airborne virus transmission, especially in a hospital setting. However, conventional filtration materials, such as nonwoven polypropylene fibers, have no inherent virucidal activity, and thus, the risk of surface contamination increases with wear time. The ability of face masks to protect against infection can be likely improved by incorporating components that deactivate viruses on contact. We present a facile method for covalently attaching antiviral quaternary ammonium polymers to the fiber surfaces of nonwoven polypropylene fabrics that are commonly used as filtration materials in N95 respirators via ultraviolet (UV)-initiated grafting of biocidal agents. Here, C12-quaternized benzophenone is simultaneously polymerized and grafted onto melt-blown or spunbond polypropylene fabric using 254 nm UV light. This grafting method generated ultrathin polymer coatings which imparted a permanent cationic charge without grossly changing fiber morphology or air resistance across the filter. For melt-blown polypropylene, which comprises the active filtration layer of N95 respirator masks, filtration efficiency was negatively impacted from 72.5 to 51.3% for uncoated and coated single-ply samples, respectively. Similarly, directly applying the antiviral polymer to full N95 masks decreased the filtration efficiency from 90.4 to 79.8%. This effect was due to the exposure of melt-blown polypropylene to organic solvents used in the coating process. However, N95-level filtration efficiency could be achieved by wearing coated spunbond polypropylene over an N95 mask or by fabricating N95 masks with coated spunbond as the exterior layer. Coated materials demonstrated broad-spectrum antimicrobial activity against several lipid-enveloped viruses, as well as Staphylococcus aureus and Escherichia coli bacteria. For example, a 4.3-log reduction in infectious MHV-A59 virus and a 3.3-log reduction in infectious SuHV-1 virus after contact with coated filters were observed, although the level of viral deactivation varied significantly depending on the virus strain and protocol for assaying infectivity