A critical review of the application of polymer of low concern regulatory criteria to fluoropolymers II: Fluoroplastics and fluoroelastomers

Cellulose Nanocrystal-in-Solvent Processing for Efficient One-Pot Upcycling of Commercial Polymeric PFAS

Upcoming regulations aim to ban per- and polyfluoroalkyl substances (PFAS), including commercial polymeric PFAS, or fluoropolymers, such as poly(tetrafluoroethylene) (PTFE) and poly(vinylidene fluoride) (PVDF), due to their environmental and toxicological impacts. However, fluoropolymers also provide crucial properties for clean energy transitions, and their regulation may hinder further technological advancements. Therefore, a facile one-pot recycling-upcycling strategy for fluoropolymers using inexpensive biomass, such as cellulose nanocrystals (CNCs), as absorbents and cocomponents for fluoro-functionalized composites could align with global sustainability goals and technological demands. Herein, we present a closed-loop CNC-in-solvent (CiS) processing system, which involves stirring fluoropolymers and CNCs in only low-polarity solvents like toluene (CiS-T). Our study reveals that CiS-T is a two-step process where the CNC-solvent interaction exposes CNCs' reducing end aldehyde protons due to solvent polarity and promotes H-F bond formation. The solvent used was recollected and reused. Additionally, we demonstrate the practical application of PTFE- and PVDF-CNC hybrids, byproducts of the CiS-T process, as performance-enhancing agents in green-energy-harvesting devices such as triboelectric nanogenerators. Our findings not only offer a sustainable method to overcome challenges from regulations against commercial fluoropolymers but also offer insights into developing an efficient, solvent-mediated CNC functionalization process that addresses forthcoming challenges in key industries.

Mineralization of fluoropolymers from combustion in a pilot plant under representative european municipal and hazardous waste combustor conditions

The goal of this study was to provide data to support mineralization of fluoropolymer waste and insignificant generation of PFAS as products of incomplete combustion (PIC) during incineration of fluoropolymer applications at their end-of-life. Destruction efficiency is not an acceptable metric to indicate mineralization and therefore we need to look for and measure products of incomplete destruction. A mixed sample of fluoropolymers representing 80% of commercial fluoropolymers was combusted at conditions representative of municipal and industrial waste incinerators operating in EU. State-of-the-art emission sampling and analytical methods (UPLC-MS/MS, GC-MS) were used for identifying and quantifying those PFAS whose standards were available. Statistical analysis of the results confirmed non-detect to negligible levels of PFAS evidencing mineralization of fluoropolymers.

Comparing occurrence of per- and polyfluoroalkyl substances (PFAS) in municipal biosolids and industrial wastewater sludge: A City of Los Angeles study

Biosolids and sludge are what remain after the liquid fraction of wastewater is separated during wastewater treatment. These high organic content matrices are known to contain organic contaminants, a few of which are the hazardous and environmentally persistent per- and polyfluoroalkyl substances (PFAS). The current study investigates whether sludge from a treatment facility serving mostly industrial establishments and biosolids from a facility serving mostly domestic dwellings retain these 'forever chemicals' similarly. Using 31 markers covering different classes of PFAS, the sludge was found to contain higher levels of PFAS (869 ± 791 ng/g; 21 of 31) than biosolids (31 ± 7 ng/g, 11 of 31). The most abundant overall was perfluorooctane sulfonic acid (PFOS), mostly in sludge (range: 71-1300 ng/g versus 0-18 ng/g in biosolids). The large PFAS concentration variability in sludge was seasonal and sinusoidal. Sludge, additionally, contained all long chain PFAS, precursors (mostly surfactant ingredients and their transformation byproducts) and short chain PFAS (perhaps because of higher moisture content). By regression, the sludge is shown to consistently contain twice as much PFAS as biosolids when the same amounts are exposed to increasing levels of PFAS. Factors observed to cause differential PFAS retention between sludge and biosolids were moisture (98.6 % and 72.1 %, respectively), chain length, input quality (industrial versus residential) and functional group. Sulfonic acids for instance are one C atom shorter than carboxylates with similar occurrence in sludge and biosolids. More studies are needed to define the roles that organic carbon of sludge/biosolids, water chemistry, temperature and factors not considered here play in partitioning PFAS between the two matrices with respect to inputs. Existing Koc values could not help in explaining observed trends, but the ratio of biosolids-to-influent concentrations was found to correlate positively with PFAS size. Using influent in the ratio, and not effluent, is novel. SYNOPSIS: Sludge and biosolids are soil amendments; they contain hazardous and persistent PFAS. Methods of decoupling PFAS from these matrices start with understanding matrix-driven PFAS partitioning as shown here.

Fire-Resistant and Thermal Stability Properties of Fluorosilicone Adhesives by Incorporation of Surface-Modified Aluminum Trihydrate

Fluorosilicone was combined with aluminum trihydrate (ATH) to induce synergistic flame-retardant and thermal-resistant properties. The surface of ATH was modified with four different silane coupling agents. The flammability and mechanical properties of the fluorosilicone/ATH composites were assessed using an UL94 vertical test and a die shear strength test. The change in shear strength was investigated under aging for 1000 h at -55 °C and 150 °C. Pure fluorosilicone had inherent fire resistance and thus achieved a V-0 rating even at 20 wt.% ATH loading. Upon addition of ATH treated with 3-glycidoxypropyl trimethoxysilane, the composites exhibited the highest shear strength of 3.9 MPa at 23 °C because of the additional crosslinking reaction of fluorosilicone resin with the epoxide functional group of the coupling agent. Regardless of the types of coupling agents, the composites exhibited similar flame retardancy at the same ATH content, with a slight reduction in shear strength at 180 °C and 250 °C. The shear strength of the adhesives gradually decreased with aging time at -55 °C, but increased noticeably from 3.9 MPa to 11.5 MPa when aged at 150 °C due to the occurrence of the additional crosslinking reaction of fluorosilicone.

TFE Terpolymers: Once Promising - Are There Still Perspectives in the 21st Century: Synthesis, Characterization, and Properties-Part I

Polytetrafluoroethylene (PTFE) exhibits outstanding properties such as high-temperature stability, low surface tension, and chemical resistance against most solvents, strong acids, and bases. However, these traits make it challenging to subject PTFE to standard polymer processing procedures, such as thermoforming and hot incremental forming. While polymer processing at temperatures above the melting point of PTFE is already demanding, the typically large molar mass of PTFE results in extremely high melt viscosities, complicating the processing of PTFE. Also, PTFE tends to decompose at temperatures close to its melting point. Therefore, fluoropolymers obtained by copolymerizing tetrafluoroethylene (TFE) with various co-monomers are studied as alternatives to PTFE (e.g., fluorinated ethylene-propylene (FEP)), combining its advantages with better processability. TFE terpolymers have emerged as desirable PTFE alternatives. This review provides an overview of the synthesis with various comonomers and microstructural analysis of PTFE terpolymers and the relationships between the microstructures of TFE terpolymers and their properties.

Dioxins vs. PFAS: Science and Policy Challenges

BACKGROUND

Dioxin-like chemicals are a group of ubiquitous environmental toxicants that received intense attention in the last two decades of the 20th century. Through extensive mechanistic research and validation, the global community has agreed upon a regulatory strategy for these chemicals that centers on their common additive activation of a single receptor. Applying these regulations has led to decreased exposure in most populations studied. As dioxin-like chemicals moved out of the limelight, research and media attention has turned to other concerning contaminants, including per- and polyfluoroalkyl substances (PFAS). During the 20th century, PFAS were also being quietly emitted into the environment, but only in the last 20 years have we realized the serious threat they pose to health. There is active debate about how to appropriately classify and regulate the thousands of known PFAS and finding a solution for these "forever chemicals" is of the utmost urgency.

OBJECTIVES

Here, we compare important features of dioxin-like chemicals and PFAS, including the history, mechanism of action, and effective upstream regulatory strategies, with the objective of gleaning insight from the past to improve strategies for addressing PFAS.

DISCUSSION

The differences between these two chemical classes means that regulatory strategies for dioxin-like chemicals will not be appropriate for PFAS. PFAS exert toxicity by both receptor-based and nonreceptor-based mechanisms, which complicates mixtures evaluation and stymies efforts to develop inexpensive assays that accurately capture toxicity. Furthermore, dioxin-like chemicals were unwanted byproducts, but PFAS are useful and valuable, which has led to intense resistance against efforts to restrict their production. Nonetheless, useful lessons can be drawn from dioxin-like chemicals and applied to PFAS, including eliminating nonessential production of new PFAS and proactive investment in environmental remediation to address their extraordinarily long environmental persistence. https://doi.org/10.1289/EHP14449.

Alternatives to Fluoropolymers for Motion-Based Energy Harvesting: Perspectives on Piezoelectricity, Triboelectricity, Ferroelectrets, and Flexoelectricity

Fluoropolymers, including polytetrafluoroethylene (PTFE, Teflon), polyvinylidene difluoride (PVDF), and fluorine kautschuk materials (FKMs, Viton) are critical polymers for applications ranging from non-stick coatings, corrosion resistant seals, semiconductor manufacturing, membranes, and energy harvesting technologies. However, the synthesis of these fluoropolymers requires the use of per- and polyfluorinated alkyl substances (PFAS) known colloquially as "forever chemicals," and as such there is a pressing need to develop alternative technologies that can serve the end-use of fluoropolymers without the environmental cost of using PFAS. Further, fluoropolymers themselves fall under the PFAS umbrella. Here, alternative mechanical-to-electrical energy harvesting polymers are reviewed and benchmarked against the leading fluoropolymer energy harvesters. These alternative technologies include nonfluoropolymer piezoelectric polymers, triboelectric nanogenerators (TENGs), ferroelectric elastomers, and flexoelectric polymers. A vision towards sustainable, non-fluoropolymer-based energy harvesting is provided.

A comprehensive review on PFAS including survey results from the EFLM Member Societies

OBJECTIVES

Per- and polyfluoroalkyl substances (PFASs) are a large class of synthetic chemicals widely used for their unique properties. Without PFAS, many medical device and in vitro diagnostic technologies would not be able to perform their intended purposes. Potential health risks associated with exposure to PFAS influence their use in IVD applications. This paper aims to assess the current situation concerning PFAS, including regulations and legislations for their use. It is important to know what happens to (PFAS) at the end of their lives in medical laboratories.

METHODS

A survey was conducted in March 2023 to collect information on the potential emission and end-of-life of PFAS-containing medical technologies in the medical laboratories of the EFLM member societies. A series of questions were presented to the EFLM national societies and the results were documented.

RESULTS

Eight respondents participated in the survey, representing EFLM member societies in seven different countries including hospital laboratories, university laboratories, and private laboratories.

CONCLUSIONS

PFAS uses in MD and IVD are influenced by several factors, including evolving regulations, advances in technology, safety and efficacy of these substances. Advancements in analytical techniques may lead to more sensitive and precise methods for detecting and quantifying PFAS in biological samples, which can be essential for IVD applications related to biomarker analysis and disease diagnosis. Collaboration among regulatory agencies, industry, research institutions, hospitals, and laboratories on a global scale can aid in establishing harmonized guidelines and standards for the use of PFAS, ensuring consistency and safety within their applications.

Per- and Polyfluoroalkyl Substances in Food Packaging: Migration, Toxicity, and Management Strategies

PFASs are linked to serious health and environmental concerns. Among their widespread applications, PFASs are known to be used in food packaging and directly contribute to human exposure. However, information about PFASs in food packaging is scattered. Therefore, we systematically map the evidence on PFASs detected in migrates and extracts of food contact materials and provide an overview of available hazard and biomonitoring data. Based on the FCCmigex database, 68 PFASs have been identified in various food contact materials, including paper, plastic, and coated metal, by targeted and untargeted analyses. 87% of these PFASs belong to the perfluorocarboxylic acids and fluorotelomer-based compounds. Trends in chain length demonstrate that long-chain perfluoroalkyl acids continue to be found, despite years of global efforts to reduce the use of these substances. We utilized ToxPi to illustrate that hazard data are available for only 57% of the PFASs that have been detected in food packaging. For those PFASs for which toxicity testing has been performed, many adverse outcomes have been reported. The data and knowledge gaps presented here support international proposals to restrict PFASs as a group, including their use in food contact materials, to protect human and environmental health.

Emission inventory of PFASs and other fluorinated organic substances for the fluoropolymer production industry in Europe

Fluoropolymers are a group of fluorinated polymers within the broad class of substances known as per- and polyfluoroalkyl substances (PFASs). During their production, a wide array of additional fluorinated organic substances (many PFASs and some not defined as PFASs) are used, formed and emitted to air and water. This study aims to assess, and make an inventory of, all emissions of PFASs and other fluorinated organic substances by the fluoropolymer production industry in Europe using available emission databases and permits. Air emissions of the fluorinated gases (i.e., chlorofluorocarbons, hydrofluorocarbons, hydrochlorofluorocarbons and perfluorocarbons (CFCs, H(C)FCs and PFCs)) by this industry have reportedly decreased between 2007 and 2021 from roughly 500 to 150 tonnes per year. Emissions of fluorosurfactants to air and water have also been reduced significantly. However, large uncertainties remain regarding the emissions of substances that are neither fluorinated gases nor fluorosurfactants but are classified as PFASs, such as polymerization by-products, chain transfer agents and fluorinated solvents. The available data indicate that the release of these substances is not decreasing but remains relatively stable. As this inventory probably underestimates emissions, further research, improved data availability and more harmonized reporting of emissions are necessary to obtain more accurate emission data for these substances. Nevertheless, based on the available data, it is clear that the emissions from fluoropolymer production plants to air and water are still significant and that the production of fluoropolymers continues to introduce persistent substances to the environment.

Detection of Perfluorooctanoic and Perfluorodecanoic Acids on a Graphene-Based Electrochemical Sensor Aided by Computational Simulations

Perfluoroalkyl carboxylic acids (PFCAs) exhibit high chemical and thermal stability, rendering them versatile for various applications. However, their notable toxicity poses environmental and human health concerns. Detecting trace amounts of these chemicals is crucial to mitigate risks. Electrochemical sensors surpass traditional methods in sensitivity, selectivity, and cost-effectiveness. In this study, a graphene nanosheet-based sensor was developed for detecting perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA). Using the Hummer method, graphene nanosheets were synthesized and characterized in terms of morphology, structural ordering, and surface topology. Ab initio molecular dynamics simulations determined the molecular interaction of per- and poly-fluoroalkyl substances (PFASs) with the sensor material. The sensor exhibited high sensitivity (50.75 μA·μM-1·cm-2 for PFOA and 29.58 μA·μM-1·cm-2 for PFDA) and low detection limits (10.4 nM for PFOA and 16.6 nM for PFDA) within the electrode dynamic linearity range of 0.05-500.0 μM (PFOA) and 0.08-500.0 μM (PFDA). Under optimal conditions, the sensor demonstrated excellent selectivity and recovery in testing for PFOA and PFDA in environmental samples, including spiked soil, water, spoiled vegetables, and fruit samples.

Conflicts of Interest in the Assessment of Chemicals, Waste, and Pollution

Pollution by chemicals and waste impacts human and ecosystem health on regional, national, and global scales, resulting, together with climate change and biodiversity loss, in a triple planetary crisis. Consequently, in 2022, countries agreed to establish an intergovernmental science-policy panel (SPP) on chemicals, waste, and pollution prevention, complementary to the existing intergovernmental science-policy bodies on climate change and biodiversity. To ensure the SPP's success, it is imperative to protect it from conflicts of interest (COI). Here, we (i) define and review the implications of COI, and its relevance for the management of chemicals, waste, and pollution; (ii) summarize established tactics to manufacture doubt in favor of vested interests, i.e., to counter scientific evidence and/or to promote misleading narratives favorable to financial interests; and (iii) illustrate these with selected examples. This analysis leads to a review of arguments for and against chemical industry representation in the SPP's work. We further (iv) rebut an assertion voiced by some that the chemical industry should be directly involved in the panel's work because it possesses data on chemicals essential for the panel's activities. Finally, (v) we present steps that should be taken to prevent the detrimental impacts of COI in the work of the SPP. In particular, we propose to include an independent auditor's role in the SPP to ensure that participation and processes follow clear COI rules. Among others, the auditor should evaluate the content of the assessments produced to ensure unbiased representation of information that underpins the SPP's activities.

Fluoropolymer Nanoparticles Synthesized via Reversible-Deactivation Radical Polymerizations and Their Applications

Fluorinated polymeric nanoparticles (FPNPs) combine unique properties of fluorocarbon and polymeric nanoparticles, which has stimulated massive interest for decades. However, fluoropolymers are not readily available from nature, resulting in synthetic developments to obtain FPNPs via free radical polymerizations. Recently, while increasing cutting-edge directions demand tailored FPNPs, such materials have been difficult to access via conventional approaches. Reversible-deactivation radical polymerizations (RDRPs) are powerful methods to afford well-defined polymers. Researchers have applied RDRPs to the fabrication of FPNPs, enabling the construction of particles with improved complexity in terms of structure, composition, morphology, and functionality. Related examples can be classified into three categories. First, well-defined fluoropolymers synthesized via RDRPs have been utilized as precursors to form FPNPs through self-folding and solution self-assembly. Second, thermally and photoinitiated RDRPs have been explored to realize in situ preparations of FPNPs with varied morphologies via polymerization-induced self-assembly and cross-linking copolymerization. Third, grafting from inorganic nanoparticles has been investigated based on RDRPs. Importantly, those advancements have promoted studies toward promising applications, including magnetic resonance imaging, biomedical delivery, energy storage, adsorption of perfluorinated alkyl substances, photosensitizers, and so on. This Review should present useful knowledge to researchers in polymer science and nanomaterials and inspire innovative ideas for the synthesis and applications of FPNPs.

Fluoropolymers as Unique and Irreplaceable Materials: Challenges and Future Trends in These Specific Per or Poly-Fluoroalkyl Substances

In contrast to some low-molar-mass per- and polyfluoroalkyl substances (PFASs), which are well established to be toxic, persistent, bioaccumulative, and mobile, fluoropolymers (FPs) are water-insoluble, safe, bioinert, and durable. These niche high-performance polymers fulfil the 13 polymer-of-low-concern (PLC) criteria in their recommended conditions of use. In addition, more recent innovations (e.g., the use of non-fluorinated surfactants in aqueous radical (co)polymerization of fluoroalkenes) from industrial manufacturers of FPs are highlighted. This review also aims to show how these specialty polymers endowed with outstanding properties are essential (even irreplaceable, since hydrocarbon polymer alternatives used in similar conditions fail) for our daily life (electronics, energy, optics, internet of things, transportation, etc.) and constitute a special family separate from other "conventional" C1-C10 PFASs found everywhere on Earth and its oceans. Furthermore, some information reports on their recycling (e.g., the unzipping depolymerization of polytetrafluoroethylene, PTFE, into TFE), end-of-life FPs, and their risk assessment, circular economy, and regulations. Various studies are devoted to environments involving FPs, though they present a niche volume (with a yearly production of 330,300 t) compared to all plastics (with 460 million t). Complementary to other reviews on PFASs, which lack of such above data, this review presents both fundamental and applied strategies as evidenced by major FP producers.

The EU's Per- and Polyfluoroalkyl Substances (PFAS) Ban: A Case of Policy over Science

The proposal by the European Chemicals Agency (ECHA) to ban over 12,000 per- and polyfluoroalkyl substances (PFAS) has sparked a debate about potential consequences for the economy, industry, and the environment. Although some PFAS are known to be harmful, a blanket ban may lead to significant problems in attempting to replace PFAS-based materials for environmental transition, as well as in medical devices and everyday products. Alternative materials may potentially be less safe, as a rush to replace PFAS would reduce the time needed for toxicological analyses. Studies have shown that PFAS exhibit a diverse range of mechanisms of action, biopersistence, and bioaccumulation potential, and should thus not be treated as a single group. This is particularly true for the class of fluoropolymers. A targeted approach that considers the specific risks and benefits of each chemical may be more effective. Moreover, the proposed ban may also have unintended consequences for the environment as PFAS use is also associated with benefits such as reducing greenhouse-gas emissions and improving energy efficiency. Policymakers must carefully weigh up the potential consequences before making a final decision on the ban.