Surface and Friction Behavior of a Silicone Surfactant Adsorbed on Model Textiles Substrates

Are Geotextiles Silent Contributors of Ultrashort Chain PFASs to the Environment?

We investigated the presence of per- and poly fluoroalkyl substances (PFASs) in woven and nonwoven polypropylene geotextiles and four nonwoven polyester geotextiles commonly used in modern geosynthetic composite lining systems for waste containment facilities such as landfills. Targeted analysis for 23 environmentally significant PFAS molecules and methods for examining "PFAS total" concentrations were utilized to assess their occurrence in geotextiles. This analysis showed that most geotextile specimens evaluated in the current investigation contained the ultrashort chain PFAS compound pentafluoropropionic acid (PFPrA). While the concentrations ranged from nondetectable to 10.84 μg/g, the average measured concentrations of PFPrA were higher in polypropylene than in polyester geotextiles. "PFAS total" parameters comprising total fluorine (TF) and total oxidizable precursors (TOPs) indicate that no significant precursor mass nor untargeted intermediates were present in geotextiles. Therefore, this study identified geotextiles as a possible source of ultrashort PFASs in engineered lined waste containment facilities, which may contribute to the overall PFAS total concentrations in leachates or liquors they are in contact with. The findings reported for the first time herein may lead to further implications on the fate and migration of PFASs in geosynthetic composite liners, as previously unidentified concentrations, particularly of ultrashort-chain PFASs, may impact the extent of PFAS migration through and attenuation by constituents of geosynthetic composite liner systems. Given the widespread use of geotextiles in various engineering activities, these findings may have other unknown impacts. The significance of these findings needs to be further elucidated by more extensive studies with larger geotextile sample sizes to allow broader, generalized conclusions to be drawn.

Study on the Relationship between Textile Microplastics Shedding and Fabric Structure

Microplastics refer to plastic fibers, particles or films less than 5 mm in diameter. Textile microplastics are an important form of microplastics, which can harm the ecological environment and human health. This paper studies the relationship between textile microplastic shedding and fabric structure to reduce microplastics pollution and reduce its impact on humans and the natural environment. Firstly, household washing is simulated by considering the main fabric type, the number of steel balls used in the washing, washing temperature, washing time and other influencing factors. An orthogonal test of the mixing level of the four factors is designed by selecting the fabric type, the number of steel balls used in washing, washing temperature and washing time, and the influencing factors is analyzed, and the best washing scheme is obtained. Then, under optimal washing conditions, the three factors and three levels of orthogonal test are designed to analyze the influence of fabric structure and external factors on the shedding of microplastics by changing the amounts of friction and insolation time. The results show that the microplastics released by knitted fabrics are significantly more under the same washing conditions than that of woven fabrics. Satin fabrics released the most microplastics and plain fabrics the least. In addition, among the external factors, the amount of friction significantly affects the production of microplastics.

Syntheses, Properties, and Aggregation Behavior of Novel Carboxylate-Based Silicone Surfactants

Two new anionic silicone surfactants were synthesized for the first time from dichloromethylvinylsilane or trichlorovinylsilane through hydrolysis-condensation and then thiol-ene reactions. Their structures were characterized by FT-IR, ¹ H NMR and ESI-MS. The surface tension (γ), critical aggregate concentration (CAC), surface pressure at CAC ( Π C A C ${\Pi _{C{\rm{A}}C} }$ ) and minimum surface area per surfactant molecule ( A min ${{A}_{\min } }$ ) were studied by surface tension and electrical conductivity, demonstrating their high surface activity at the gas/liquid interface. Transmission electron microscopy measurements showed that uniform spherical aggregates former in aqueous solution for both surfactants. Moreover, the size of the aggregates was determined to be in the range from 50 to 300 nm by dynamic light scattering.

Modulating the surface and mechanical properties of textile by oil-in-water emulsion design

The synergistic effect of oil viscosity and oil droplet size on the deposition profile of oil on cotton fabric was studied using polydimethylsiloxane (PDMS) as a model oil-in-water emulsion system. Under the same preparation conditions, low viscosity PDMS produced emulsions containing small droplets, which resulted in a uniform surface deposition profile, whilst high viscosity PDMS resulted in a localised deposition profile. Interfacial phenomena such as wicking and penetration of PDMS into cotton fabrics were found to be viscosity-dependent, which agrees with the surface deposition data. Both mechanical characterisation (friction, compression, stiffness) and consumer evaluation confirm that the fabrics treated by the emulsion containing low viscosity PDMS were preferred, suggesting that a homogeneous surface deposition and an excellent penetration profile of PDMS are critical for maximising tactile sensorial benefits, which could be accomplished by optimising the emulsion formulation to contain oil of low viscosity and small PDMS droplets.

The synergistic effect of oil viscosity and oil droplet size on the deposition profile of oil on cotton fabric was studied using polydimethylsiloxane (PDMS) as a model oil-in-water emulsion system.

Synthesis and Solution Behavior of Sulfonate-Based Silicone Surfactants with Specific, Atomically Defined Hydrophobic Tails

A series of sulfonate-based silicone surfactants with different hydrophobic groups were synthesized. Two synthetic strategies are introduced to permit exquisite control over the hydrophobic moieties. Solution behavior of these surfactants was investigated by surface tensiometry, electrical conductivity, transmission electron microscopy, and dynamic light scattering. The results indicate that the aqueous behavior of the surfactants was distinctly influenced by the hydrophobic groups. Subtle distinctions in surfactant-related properties, which can be attributed to the three-dimensional molecular structures of the surfactants, can be seen for compounds with different hydrophobic moieties. Contact angle results of these surfactants indicate that they have super dispersal ability with the potential value in agriculture.

Effect of grafted oligopeptides on friction

Frictional and normal forces in aqueous solution at 25 °C were measured between a glass particle and oligopeptide films grafted from a glass plate. Homopeptide molecules consisting of 11 monomers of either glutamine, leucine, glutamic acid, lysine, or phenylalanine and one heteropolymer were each "grafted from" an oxidized silicon wafer using microwave-assisted solid-phase peptide synthesis. The peptide films were characterized using X-ray photoelectron spectroscopy and secondary ion mass spectrometry. Frictional force measurements showed that the oligopeptides increased the magnitude of friction compared to that on a bare hydrophilic silicon wafer but that the friction was a strong function of the nature of the monomer unit. Overall we find that the friction is lower for more hydrophilic films. For example, the most hydrophobic monomer, leucine, exhibited the highest friction whereas the hydrophilic monomer, polyglutamic acid, exhibited the lowest friction at zero load. When the two surfaces had opposite charges, there was a strong attraction, adhesion, and high friction between the surfaces. Friction for all polymers was lower in phosphate-buffered saline than in pure water, which was attributed to lubrication via hydrated salt ions.