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Within the textile industry PFAS coatings have been used to give fabrics and other textile materials liquid- and dirt-repellent properties. However, the wide-spread use of PFAS has severe effects on the environment and human health which has led to regulations and legislation regarding the use of PFAS. A new proposal was presented in 2023 to The European Chemicals Agency which would see to ban most if not all uses of PFAS unless they prove to be necessary. This proposal along with the EUs Chemicals Strategy from 2020 highlights the need for alternatives to PFAS. The aim of this study is to conclude a list of possible alternatives to PFAS through the peer reviewed articles. The list is presented through a rapid review to see what the “state of the art” of the research for alternatives is. The rapid review is conducted with two search blocks in two different databases. After removing duplicates, an abstract review and a full article review, the study ends up with 23 articles stating possible alternatives for PFAS. Out of the 23 articles, 10 of them discuss coatings that contain a different type of PFAS (short- chained PFAS) while the remaining 13 articles discuss non-fluorinated alternatives. Based on the rapid review results, the alternatives are analyzed, compared and discussed for whether they can be part of the solution. The study shows that while there are alternatives to PFAS the applications of the alternatives need to be discussed. There is a need for more research for a lot of the fluorine-free alternatives found, as a lot of them only test for hydrophobicity, but the results show that the industry is headed in the right direction. To conclude, the study highlights the need for further research of alternatives that are on par with the currently used PFAS

The purpose of this project is to analyse and find potential alternatives to fluorinated firefighting foams. The unique oleophobic and hydrophobic properties of fluorinated firefighting foams prevent them from mixing with oils, making them the current medium of choice for efficiently controlling oil fires. Unfortunately, these foams negatively impact the environment, are not biodegradable, and instead bioaccumulate. This can lead to the presence of fluorocarbons in animals and humans, which presents a currently unknown health risk. This project focusses on silica nanoparticles coated in various surfactants as a potential alternative to stabilise foams for these applications. Silica can be treated with alumina to form a positively charged surface, therefore anionic surfactants could also be considered and comparisons between cationic surfactants and anionic surfactants could be drawn. Small-angle neutron scattering (SANS) experiments showed that similarly charged surfactants and nanoparticles did not interact, whereas oppositely charged surfactants did interact with the silica nanoparticles. The foamability of these systems was analysed using a standard Ross-Miles set-up, and foam degradation was measured by looking at the change in foam height over time: this was validated by surface tension measurements. It was found that high concentrations of surfactant were necessary for adequate surfactant-coated silica nanoparticle foamability, however, these foams then proved to have better stability than pure surfactant foams. The oleophobicity of the systems was also evaluated by looking at spreadability on heptane, absorption of an oleophilic dye, and contact angles. The oleophobicity decreased with increasing surfactant concentration, until it reached a plateau at around 0.05 M. Combining this with the foamability experiments suggests there may be an optimum concentration to maximise oleophobicity and foamability, which would be interesting for further research.

A basic requirement of a plasma etching process is fidelity of the patterned organic materials. In photolithography, a He plasma pretreatment (PPT) based on high ultraviolet and vacuum ultraviolet (UV/VUV) exposure was shown to be successful for roughness reduction of 193nm photoresist (PR). Typical multilayer masks consist of many other organic masking materials in addition to 193nm PR. These materials vary significantly in UV/VUV sensitivity and show, therefore, a different response to the He PPT. A delamination of the nanometer-thin, ion-induced dense amorphous carbon (DAC) layer was observed. Extensive He PPT exposure produces volatile species through UV/VUV induced scissioning. These species are trapped underneath the DAC layer in a subsequent plasma etch (PE), causing a loss of adhesion. Next to stabilizing organic materials, the major goals of this work included to establish and evaluate a cyclic fluorocarbon (FC) based approach for atomic layer etching (ALE) of SiO2 and Si; to characterize the mechanisms involved; and to evaluate the impact of processing parameters. Periodic, short precursor injections allow precise deposition of thin FC films. These films limit the amount of available chemical etchant during subsequent low energy, plasma-based Ar+ ion bombardment, resulting in strongly time-dependent etch rates. In situ ellipsometry showcased the self-limited etching. X-ray photoelectron spectroscopy (XPS) confirms FC film deposition and mixing with the substrate. The cyclic ALE approach is also able to precisely etch Si substrates. A reduced time-dependent etching is seen for Si, likely based on a lower physical sputtering energy threshold. A fluorinated, oxidized surface layer is present during ALE of Si and greatly influences the etch behavior. A reaction of the precursor with the fluorinated substrate upon precursor injection was observed and characterized. The cyclic ALE approach is transferred to a manufacturing scale reactor at IBM Research. Ensuring

Perfluoropentane (PFP)-based oxygen-loaded nanobubbles (OLNBs) were previously proposed as adjuvant therapeutic tools for pathologies of different etiology sharing hypoxia as a common feature, including cancer, infection, and autoimmunity. Here we introduce a new platform of oxygen nanocarriers, based on 2H,3H-decafluoropentane (DFP) as core fluorocarbon. These new nanocarriers have been named oxygen-loaded nanodroplets (OLNDs) since DFP is liquid at body temperature, unlike gaseous PFP. Dextran-shelled OLNDs, available either in liquid or gel formulations, display spherical morphology, ∼600 nm diameters, anionic charge, good oxygen carrying capacity, and no toxic effects on human keratinocytes after cell internalization. In vitro OLNDs result more effective in releasing oxygen to hypoxic environments than former OLNBs, as demonstrated by analysis through oxymetry. In vivo, OLNDs effectively enhance oxy-hemoglobin levels, as emerged from investigation by photoacoustic imaging. Interestingly, ultrasound (US) treatment further improves transdermal oxygen release from OLNDs. Taken together, these data suggest that US-activated, DFP-based OLNDs might be innovative, suitable and cost-effective devices to topically treat hypoxia-associated pathologies of the cutaneous tissues.

Fluorocarbon thin films were formed by radio-frequency magnetron sputtering using a polytetrafluoroethylene target with different substrate temperatures in the range −5 to 200 °C. Using X-ray diffraction and Fourier transform infrared spectroscopy, it was confirmed that the films were amorphous and contained C–F bonds. X-ray photoelectron spectroscopy measurements indicated that the amount of cross-linking in the films increased with increasing substrate temperature. Corresponding to the change in the molecular structure, the adhesion strength of the films to the Si substrate, estimated by micro-scratch testing, improved with increasing substrate temperature.

Anatomic force microscope and the colloidal probe technique are used to probe the interaction between a hydrophobic particle and a hydrophobic surface in water. The characteristics of the observed force curves strongly suggest that a gas bubble is formed when the particle is moved toward the surface and that the bubble ruptures when the particle subsequently is retracted from the surface. We demonstrate that this type of interaction is not unique for hydrophobic surfaces in water since the interaction between hydrophilic surfaces in air provides very similar force curves. However, the interaction between hydrophobic surfaces vanish if water is replaced by an organic solvent with low polarity. The bridging bubble model is employed to explain the hysteresis observed between approach and retraction force traces and experimental conditions where the hysteresis can be almost eliminated are identified. Finally, it is demonstrated that the hydrophobic interaction is strongly temperature dependent and this dependence can be attributed mainly to the decreasing solubility of air in water with increasing temperature., QC 20110531

Separation selectivity in electrokinetic chromatography (EKC) is directly affected by the chemistry and solvent characteristics of the pseudostationary phase (PSP). The chemical selectivity of micellar PSPs has been previously demonstrated to vary significantly between anionic and cationic surfactants as well as between hydrocarbon and fluorocarbon surfactants. Polymeric PSPs have also been demonstrated to provide unique selectivity. In the current study, four cationic polymeric pseudo-stationary phases, two of which have perfluorinated pendant groups, are introduced and characterized as PSPs in EKC. Their performance and selectivity is compared to conventional micellar PSPs with similar structure. The solvation characteristics and selectivity of the four polymers most closely resemble those observed for cationic micelles. The polymers are all more cohesive and more polar than their hydrocarbon micellar counterparts. The fluorocarbon PSPs did show preferential interaction with fluorocarbon solutes, were somewhat more cohesive, and were stronger hydrogen bond donors. However, the presence of fluorocarbon moieties did not have as dramatic an effect on selectivity as was observed and published previously for fluorocarbon micelles. This may result from the selectivity being dominated by the presence of the cationic head groups or from the fluorocarbon character of the pendant groups being moderated by the presence of hydrocarbon functionality on the polymer back-bones. (c) 2005 Elsevier B.V. All rights reserved.

A series of fluorinated polymers were studied using time-of-flight secondary ion mass spectrometry (ToF-SIMS) to investigate the relationship between the structures of the polymers and secondary ions. The influence of fluorocarbon segment length on the formation of secondary ions in a ToF-SIMS process was studied. The characteristic negative and positive ions were found to be related to the chemical structure of the repeat units of the polymers. The ToF-SIMS results provided some useful information on the fragmentation mechanism of positive and negative secondary ions. The results indicate that recombination of the ions in the gas phase is unlikely in a static SIMS process. Copyright (C) 2002 John Wiley Sons, Ltd.

The suitability of using octafluorocyclobutane (C4F8) patches as hydrophobic valves in microfluidic biochemical applications has been shown. A technique has been developed to generate lithographically defined C4F8 hydrophobic patches in deep reactive ion-etched silicon channels. Some of the advantages of this process are that no specific cleaning of the substrate is required, C4F8 is deposited on the sidewalls and the bottom of the channels, a standard photoresist mask can be used to define the patches, and that it is a fast and convenient dry chemical process performed by a standard inductively coupled plasma etcher using the Bosch process. Different patch lengths (200-1000 mum) of C4F8 were deposited in 50 mum wide channels to evaluate which size is most suitable for microfluidic biochemical applications. The valve function of the hydrophobic patches was tested for the following liquids: DD water, acetone, propanol, bead solution and a mixture used for pyrosequencing of DNA. Patch lengths of 200 mum of C4F8 successfully stopped each solution for at least 20 consecutive times. The C4F8 film resists water for at least 5 h. The hydrophobic valve also resists very high concentrations (25%) of surfactants (Tween 80). C4F8 shows a much higher resistance towards water and surface active solutions than previous hydrophobic patches. However, 50% Tween 80 was not stopped at all by the hydrophobic patch. An applied pressure of 760 Pa at the inlet was needed for water to over-run the hydrophobic patch., QC 20100525

Some properties of a 90% C2H2P4 gas mixture, used to operate resistive plate chambers in the avalanche mode, are determined by comparing the experimental results with the prediction of simple analytical calculations. The fast charge distribution of the signal induced on pick-up electrodes is reproduced by means of a Monte Carlo simulation of the avalanche development. In addition, predictions for a gas mixture with poor content of C2H2F4 are given for comparison.

We studied the toxicity of perfluorophenanthrene (PFP), used as short-, medium-, or long-term internal tamponading substance, on the rabbit choroid and retina. The aim was the check whether PFP is tolerated as a tamponade in the eye or damages the retina, and if any such damage is due to toxicity or to emulsification which may stimulate phagocytosis.

Groups of 120-mm bore angular-contact ball bearings made from AISI M- 50 steel were fatigue tested at a temperature of 600 deg F (588 K) and a speed of 12 000 rpm with a synthetic paraffinic oil, a fluorocarbon, and a 5P4E polyphenyl ether. Under a low oxygen environment, the synthetic paraffinic oil and the fluorocarbon gave bearing lives approximately 14 and 3 times AFBMA-predicted (catalog) life, respectively. With the poly-phenly ether, bearing life was less than AFBMA-predicted (catalog) life in an air environment. For the synthetic paraffinic oil and the fluorocarbon, bearing fatigue was subsurface initiated. For the polyphenyl ether, bearing failure was mainly from surface distress, wear, and superficial pitting.