Health & Environmental Research Online (HERO)


Per- and Polyfluoroalkyl Substances (PFAS)


138 References Were Found:

Journal Article
Journal Article

Non-equilibrium responses of PFPE lubricants with various atomistic/molecular architecture at elevated temperature

Authors: Chung, PilS; Song, W; Biegler, LT; Jhon, MS (2017) HERO ID: 3860653

[Less] During the operation of hard disk drive (HDD), the perfluoropolyether (PFPE) lubricant experiences elastic . . . [More] During the operation of hard disk drive (HDD), the perfluoropolyether (PFPE) lubricant experiences elastic or viscous shear/elongation deformations, which affect the performance and reliability of the HDD. Therefore, the viscoelastic responses of PFPE could provide a finger print analysis in designing optimal molecular architecture of lubricants to control the tribological phenomena. In this paper, weexamine the rheological responses of PFPEs including storage (elastic) and loss (viscous) moduli (G' and G '') by monitoring the time-dependent-stress-strain relationship via non-equilibrium molecular dynamics simulations. We analyzed the rheological responses by using Cox-Merz rule, and investigated the molecular structural and thermal effects on the solid-like and liquid-like behaviors of PFPEs. The temperature dependence of the endgroup agglomeration phenomena was examined, where the functional endgroups are decoupled as the temperature increases. By analyzing the relaxation processes, the molecular rheological studies will provide the optimal lubricant selection criteria to enhance the HDD performance and reliability for the heat-assisted magnetic recording applications. (C) 2017 Author(s).

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Stereolithography of perfluoropolyethers for the microfabrication of robust omniphobic surfaces

Authors: Credi, C; Levi, M; Turri, S; Simeone, G (2017) HERO ID: 3860654

[Less] In this work, we provide a simple and straightforward method for the fabrication of stable highly hydrophobic . . . [More] In this work, we provide a simple and straightforward method for the fabrication of stable highly hydrophobic and oleophobic surfaces by applying stereolithography (SL) to perfluoropolyethers (PFPEs). Inspired by the liquid repellency widely shown in nature, our approach enables to easily mimic the interplay between the chemistry and physics by microtexturing low surface tension PFPEs. To this end, UV-curable resins suitable for SL-processing were formulated by blending multifunctional (meth)acrylates PFPEs oligomers with photoinitiator and visible dyes whose content was tuned to tailor resin SL sensitivities. Photocalorimetric studies were also performed to investigate the curing behavior of the different formulations upon SL light exposure. Being the first example of stereolithography applied to PFPEs, stereolithographic processability of new developed PFPEs photopolymer was compared with a standard photoresist taken as benchmark (DL260 (R)). Optimized formulations were characterized by reduced laser penetration depth (<75 mu m) and small critical energies thus enabling for fast printing of micrometric structures. Arrays of cylindrical pillars (85 pm diameter, 400 mu m height) characterized by varied pillars spacing (200 divided by 350 mu m) were rapidly printed with high fidelity as attested by SEM examination. Contact angle measurements in static and dynamic conditions were performed to investigate the surface properties of textured samples using water and oil as the probing liquids. PFPEs liquid repellent performances were compared with those from DL260 (R) textured surfaces arrayed by SL. High water contact angles coupled with low hysteresis asserted that high hydrophobic surfaces were successfully obtained and best-performing textured surfaces were also characterized by high oil repellency. Finally, this study demonstrated that omniphobic surfaces can be easily realized via a single-step, cost-effective, and time-saving process. (C) 2017 Elsevier B.V. All rights reserved.

Journal Article
Journal Article

Multiscale modeling of organic molecules contamination in head-disk interface under high thermal stress

Authors: Song, W; Chung, PilS; Bielger, LT; Jhon, MS (2017) HERO ID: 3860657

[Less] Heat assisted magnetic recording (HAMR) which locally reduces coercivity with a laser pulse, is currently . . . [More] Heat assisted magnetic recording (HAMR) which locally reduces coercivity with a laser pulse, is currently the most promising technology to achieve areal density beyond 10 Tbit/in(2). However, due to the extreme operating condition of HAMR, the head-disk interface (HDI) suffers from extensive depletion and contamination of organic molecules. Our previous studies indicate that the conventional linear perfluoropolyether (PFPE) lubricants/grease molecules are not suitable for the severe thermal stress especially when coupled with external fields as the lubricant layer can be depleted and damaged. To simulate the molecular evaporation phenomena, we introduced novel multiscale modeling scheme, "Collection Of Spheres" model, which can predict mesoscale phenomena based on the atomistic/molecular level details via reduced order method. We have examined how the molecular architect affects evaporation under various degree of thermal stress (e.g., peak temperature and duration). Specifically, we examined several PFPEs (e.g., Z, Zdol, and Ztetraol) to study the effect of back-bone and end group properties on evaporation. Our multiscale model can provide holistic simulation of the HDI and provide molecular design criteria for HAMR device. (C) 2017 Author(s).

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Temporal trends of PFSAs, PFCAs and selected precursors in Australian serum from 2002 to 2013

Authors: Eriksson, U; Mueller, JF; Toms, LL; Hobson, P; Kärrman, A (2017) Environmental Pollution 220:168-177. HERO ID: 3858507

[Less] Per- and polyfluoroalkyl substances (PFASs) are a family of compounds that includes numerous compound . . . [More] Per- and polyfluoroalkyl substances (PFASs) are a family of compounds that includes numerous compound classes. To date, only a subset of these PFASs have been studied thoroughly in the general population. In this study, pooled serum samples from Australia collected in 2002-2013 were analyzed for PFASs according to gender and age (age categories of 0-4 years, 5-15 years, 16-30 years, 31-45 years, 46-60 years, and >60 years), in total 54 pooled samples and 4920 individuals. Compound classes included were perfluorocarboxylic acids (PFCAs), perfluorosulfonic acids (PFSAs), and two groups of PFCA precursor compounds; polyfluoroalkyl phosphate diesters (diPAPs), and fluorotelomer sulfonic acids (FTSAs). Several PFASs that were not reported in previous studies of Australian serum samples were found in this sample set including; diPAPs, FTSAs, perfluoropentane sulfonic acid (PFPeS), perfluoroheptane sulfonic acid (PFHpS), perfluoroheptane carboxylic acid (PFHpA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), and perfluorotridecanoic acid (PFTrDA). Various temporal trends were observed with a significant reduction (p < 0.05) between 2002 and 2013 for 8:2 FTSA, perflurohexane sulfonic acid (PFHxS), PFHpS, PFOS, and perflurooctanoic acid (PFOA). Levels of longer-chained PFDA and PFUnDA started to decrease more recently, between 2006 and 2013, while PFDoDA increased during the same time period. Higher levels in younger age groups (0-4 and 5-15 years) compared to adults (>15 years) were found for 8:2 FTSA and PFHpA, while levels of PFHpS, PFOS, PFUnDA, PFDoDA and PFTrDA were higher in adult age groups compared to younger age groups. Gender-specific patterns were seen for PFOA, PFHxS, PFHpS and PFOS, where levels were lower in women. Changes in manufacturing processes were reflected in the temporal time trends, and differences in bioaccumulation potential between homologues could be associated with age trends. Our results emphasize the importance of including emerging classes of PFASs in biomonitoring studies.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Temporal trends of PFSAs, PFCAs and selected precursors in Australian serum from 2002 to 2013 : Supplementary materials

Authors: Eriksson, U; Mueller, JF; Toms, LL; Hobson, P; Kärrman, A (2017) Environmental Pollution 220. HERO ID: 3981676

Abstract: Supplemental materials

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Liquid perfluoropolyether electrolytes with enhanced ionic conductivity for lithium battery applications

Authors: Olson, KR; Wong, DHC; Chintapalli, M; Timachova, K; Janusziewicz, R; Daniel, WFM; Mecham, Sue; Sheiko, S; Balsara, NP; Desimone, JM (2016) HERO ID: 3860642

[Less] We prepared nonflammable liquid polymer electrolytes for lithium-ion batteries by mixing ethoxylated . . . [More] We prepared nonflammable liquid polymer electrolytes for lithium-ion batteries by mixing ethoxylated perfluoropolyethers (PFPEs) with LiN(SO2CF3)(2) salt. Interestingly, we identified the presence of chain coupling in the PFPE polymers and their functionalized derivatives, resulting in a mixture of PFPEs with varying molecular weights. The distribution of molecular weights, along with PFPE's multiple functionalities, allows systematic manipulation of structure to enhance electrochemical and physical properties. Furthermore, the electrolytes exhibited a wide thermal stability window (5% degradation temperature >180 degrees C). Despite substantial increases in viscosity upon loading the PFPEs with lithium salt, the conductivity (sigma approximate to 5 x 10(-5) S cm(-1) at 28 degrees C) of the novel electrolytes was about an order of magnitude higher than that of our previously reported PFPE electrolytes. Ethoxylated derivatives of PFPE electrolytes exhibit elevated conductivity compared to non-ethoxylated derivatives, demonstrating our capability to enhance the conductive properties of the PFPE platform by attaching various functional groups to the polymer backbone. (C) 2016 Elsevier Ltd. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Study on Nanometer-Thick Room-Temperature Ionic Liquids (RTILs) for Application as the Media Lubricant in Heat-Assisted Magnetic Recording (HAMR)

Authors: Gong, X; West, B; Taylor, A; Li, Lei (2016) HERO ID: 3860628

[Less] Nanometer-thick room-temperature ionic liquids (RTILs) have been studied for potential application as . . . [More] Nanometer-thick room-temperature ionic liquids (RTILs) have been studied for potential application as media lubricants for heat-assisted magnetic recording (HAMR) in the hard disk drive (HDD) industry. The RTILs containing fluorinated anions are readily solvable in Vertrel XF solvent and can be applied on the media by dip-coating, which is compatible to the current industry process. The thermal stability, topography and tribological performance of the RTILs nanofilms have been characterized by thermogravametric analysis (TGA), ellipsometry, atomic force microscopy (AFM) and nanotribometry. The experimental results showed that RTILs are thermally more stable than the state-of-the-art media lubricants in HDDs, i.e., perfluoropolyethers (PFPEs) such as diolic perfluoropoly(oxyethylene-ran-oxymethylene) commercially known as Zdol. The lubricant uniformity of most studied RTILs is better than that of Zdol, and no dewetting is observed even when the RTIL nanofilm is as thick as 10 nm. The friction coefficient of subnanometer-thick RTILs is lower than that of Zdol. The structure-property relationship and the possible structure design for the future improvement have been discussed.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Liver and kidney cells cultures in a new perfluoropolyether biochip

Authors: Jellali, R; Paullier, P; Fleury, MJ; Leclerc, E (2016) HERO ID: 3860633

[Less] Although microfluidics represents a promising technology for drug screening industry and toxicity tests, . . . [More] Although microfluidics represents a promising technology for drug screening industry and toxicity tests, their industrial applications using cells are limited by drawbacks of the weakly mass production capability of the biochips. In this work, we report the fabrication of resistant fluorinated microfluidic devices using a material widely used in polymer industries. To build the microdevices, two patterned layers with precise and regular microchannels were developed by photocuring of perfluoropolyethers (PFPEs). These layers were successfully sealed by UV irradiation. Then, Liver HepG2/C3A and kidney MDCK cells were cultured in PFPE biochips. The growth, cell viability and basal metabolism of cells cultured in PFPE biochips were studied and compared with results obtained using polydimethylsiloxane (PDMS) biochips. The results have shown that the cells can attach to the biochip bottom, spread, and proliferate well in PFPE biochip (similar to the cells in PDMS biochip). Furthermore, metabolisms of cell cultures in PFPE biochip, such as glucose consumption, albumin and urea productions, were proved similar to the results obtained in PDMS biochips. These results highlighted the functionality of the HepG2/C3A and MDCK cells in PFPE microfluidic devices and illustrated their potential to replace PDMS devices. (C) 2016 Elsevier B.V. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Rheological Properties of PFPE Lubricants at Elevated Temperatures

Authors: Chung, PilS; Song, W; Biegler, LT; Jhon, MS (2016) HERO ID: 3860652

[Less] During the intermittent contact between the head and the disk of the hard disk drive (HDD), the perfluoropolyether . . . [More] During the intermittent contact between the head and the disk of the hard disk drive (HDD), the perfluoropolyether (PFPE) lubricant experiences shear/ elongation deformation. Therefore, the molecular rheology of PFPE becomes critically important in designing optimal lubricants that control the friction and wear. In this paper, we examine, for the first time, the rheological responses of nanoblended PFPEs, including storage and loss moduli (G' and G ''), by monitoring the time-dependent stress-strain relationship via nonequilibrium molecular dynamics simulations. We observed that the nonfunctional PFPEs (Fomblin Z-type) exhibit liquid-like behavior, while agglomeration behavior was observed for the functional PFPEs (Fomblin Zdol-type). In addition, strong endgroup couplings due to functional endgroup weaken as the temperature increases. For binary blended PFPEs, we also observed similar phenomena, which strongly depends on the blend ratio and imposed condition (e.g., temperature and oscillatory frequency). We established a finger print analysis via G'-G '' plots for different blend ratios and temperatures. By analyzing the blended PFPE relaxation processes, our results provide the optimal parameters for lubricant selection criteria to enhance the HDD performance.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Direct photo-patterning of hyaluronic acid baits onto a fouling-release perfluoropolyether surface for selective cancer cell capture and immobilization

Authors: Credi, C; De Marco, C; Molena, E; Nava, MM; Raimondi, MT; Levi, M; Turri, S (2016) Materials Science and Engineering C: Materials for Biological Applications 62:414-422. HERO ID: 3860594

[Less] A simple photolithographic process for directly patterning glycidyl methacrylate modified hyaluronic . . . [More] A simple photolithographic process for directly patterning glycidyl methacrylate modified hyaluronic acid features onto UV curable perfluoropolyether-based surfaces is presented. Due to the versatility of the developed method, HA spotted areas with different geometrical features could be rapidly and inexpensively designed. In addition, the excellent antifouling and fouling-release properties of the substrates enabled direct HA baits photo-grafting onto PFPEs without further surface passivation or chemical modification to avoid not specific adsorption. The aim of the study was to locally switch the surface properties of the PFPEs from cells and protein repulsive to adherent. Particularly, we exploited HA well-known preferential interactions with CD44 transmembrane receptors to selectively immobilize cancer cells. Living cell arrays offer a higher-resolution visualization of HA-CD44 interactions and may provide a deep insight into understanding molecular mechanisms needed to develop selective therapies and diagnosis against tumor growth.