| 1. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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Directed self-assembly of silica nanoparticles in ionic liquid-spun cellulose fibers
- 2019
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 553, s. 167-176
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Tidskriftsartikel (refereegranskat)abstract
- The application range of man-made cellulosic fibers is limited by the absence of cost- and manufacturing-efficient strategies for anisotropic hierarchical functionalization. Overcoming these bottlenecks is therefore pivotal in the pursuit of a future bio-based economy. Here, we demonstrate that colloidal silica nanoparticles (NPs), which are cheap, biocompatible and easy to chemically modify, enable the control of the cross-sectional morphology and surface topography of ionic liquid-spun cellulose fibers. These properties are tailored by the silica NPs’ surface chemistry and their entry point during the wet-spinning process (dope solution DSiO2 or coagulation bath CSiO2). For CSiO2-modified fibers, the coagulation mitigator dimethylsulphoxide allows for controlling the surface topography and the amalgamation of the silica NPs into the fiber matrix. For dope-modified fibers, we hypothesize that cellulose chains act as seeds for directed silica NP self-assembly. This results for DSiO2 in discrete micron-sized rods, homogeneously distributed throughout the fiber and for glycidoxy-surface modified DSiO2@GLYEO in nano-sized surface aggregates and a cross-sectional core-shell fiber morphology. Furthermore, the dope-modified fibers display outstanding strength and toughness, which are both characteristic features of biological biocomposites.
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| 2. |
- Argyri, Smaragda Maria, 1994, et al.
(författare)
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Contact-free measurement of surface tension on single droplet using machine learning and acoustic levitation
- 2023
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 640, s. 637-646
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis Acoustic levitation provides the possibility to deform levitated droplets in a controllable, and quantifiable manner, thus offering a means to measure the surface tension of a liquid droplet based on its deviation from sphericity. However, for new generation of multi-source and highly stable acoustic levitators, no model relates the acoustic pressure field to the deformation and surface tension. Utilizing a machine learning algorithm is expected to identify correlations between the experimental data without any set preconditions. Experiments A series of aqueous surfactant solutions with a large range of surface tensions were prepared, and evaporated under levitation, while the acoustic pressure was varied. A dataset of over 50,000 images was used for the training and evaluation of the machine learning algorithm. Prior to that, the machine learning approach was validated on in silico data that also included artificial noise. Findings We achieved high accuracy in predicting the surface tension of single standing droplets (±0.88 mN/m), and we surpassed certain physical conditions related to the size, and shape of the suspended samples that simpler theoretical models are subject to.
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| 3. |
- Argyri, Smaragda Maria, 1994, et al.
(författare)
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Customized and high-performing acoustic levitators for contact-free experiments
- 2024
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Ingår i: Journal of Science: Advanced Materials and Devices. - 2468-2284 .- 2468-2179. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- Acoustic levitators are becoming an increasingly common research instrumentation for contact-free, lab-in-a-droplet studies. Recently, levitators that employ multiple, small, ultrasonic transducers have gained popularity, given their low price, temperature and spatial stability, low voltage, and accessibility. Yet, the current state-of-the-art device, TinyLev, presents limitations for certain applications in terms of stability, strength, and compactness. Herein, we developed three new levitators and evaluated the effect of the construction parameters (e.g., distance of opposing arrays, number and arrangement of transducers, etc.) on their performance. Compared to TinyLev, the best performing levitator from this work had half the number of transducers while presenting 1.7 and 3.5 times higher levitation capacity along the horizontal and vertical configurations, respectively, while the horizontal and vertical stability of a levitated object was improved 4.7 and 2.0 times, respectively. Additionally, we present a direct means to evaluate the acoustic radiation net force acting on a deformable object for uniaxial levitators, without the use of a microphone or a schlieren deflectometer for this type of levitators. The theoretical and experimental observations provide insights for adapting the acoustic levitator design for specific applications. Finally, we developed an open-source software which allows the evaluation of the acoustic pressure field generated by customized designs and provides the necessary files for 3D printing the scaffold of the levitator. This study aims to increase accessibility and promote further developments in contact-free experiments.
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| 4. |
- Baglioni, M., et al.
(författare)
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Nanostructured fluids from degradable nonionic surfactants for the cleaning of works of art from polymer contaminants
- 2014
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 10:35, s. 6798-6809
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured fluids containing anionic surfactants are among the best performing systems for the cleaning of works of art. Though efficient, their application may result in the formation of a precipitate, due to the combination with divalent cations that might leach out from the artifact. We propose here two new aqueous formulations based on nonionic surfactants, which are non-toxic, readily biodegradable and insensitive to the presence of divalent ions. The cleaning properties of water-nonionic surfactant-2-butanone (MEK) were assessed both on model surfaces and on a XIII century fresco that could not be cleaned using conventional methods. Structural information on nanofluids has been gathered by means of small-angle neutron scattering, dynamic light scattering and nuclear magnetic resonance with diffusion monitoring. Beside the above-mentioned advantages, these formulations turned out to be considerably more efficient in the removal of polymer coatings than those based on anionic surfactants. Our results indicate that the cleaning process most likely consists of two steps: initially, the polymer film is swollen by the MEK dissolved in the continuous domain of the nanofluid; in the second stage, surfactant aggregates come into play by promoting the removal of the polymer film with a detergency-like mechanism. The efficiency can be tuned by the composition and nature of amphiphiles and is promoted by working as close as possible to the cloud point of the formulation, where the second step proceeds at maximum rate.
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| 5. |
- Barai, Manas, et al.
(författare)
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Interfacial and Aggregation Behavior of Dicarboxylic Amino Acid-Based Surfactants in Combination with a Cationic Surfactant
- 2019
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 35:47, s. 15306-15314
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Tidskriftsartikel (refereegranskat)abstract
- The interfacial and micellization behavior of three dicarboxylic amino acid-based anionic surfactants, abbreviated as AAS (N-dodecyl derivative of -aminomalonate, -aspartate, and -glutamate) in combination with hexadecyltrimethylammonium bromide (HTAB) were investigated by surface tension, conductance, UV–vis absorption/emission spectroscopy, dynamic light scattering (DLS), and viscosity studies. Critical micelle concentration (CMC) values of the surfactant mixtures are significantly lower than the predicted values, indicating associative interaction between the components. Surface excess, limiting molecular area, surface pressure at the CMC, and Gibbs free energy indicate spontaneity of the micellization processes compared to the pure components. CMC values were also determined from the sigmoidal variation in the plot of micellar polarity and pyrene UV–vis absorption/emission intensities with surfactant concentration. The aggregation number, determined by static fluorescence quenching method, increases with decreasing mole fraction of the AAS (αAAS), where the micelles are mainly dominated by the HTAB molecules. The size of the micelle increases with decreasing αAAS, leading to the formation of larger and complex aggregates, as also supported by the viscosity studies. Micelles comprising 20–40 mol % AAS are highly viscous, in consonance with their sizes. Some of the mixed surfactant systems show unusual viscosity (shear thickening and increased viscosity with increasing temperature). Such mixed surfactant systems are considered to have potential in gel-based drug delivery and nanoparticle synthesis.
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| 6. |
- Baresel, Christian, et al.
(författare)
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Functionalized magnetic particles for water treatment
- 2019
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Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 5:8
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we have taken the concept of water treatment by functionalized magnetic particles one step forward by integrating the technology into a complete proof of concept, which included the preparation of surface modified beads, their use as highly selective absorbents for heavy metals ions (Zinc, Nickel), and their performance in terms of magnetic separation. The separation characteristics were studied both through experiments and by simulations. The data gathered from these experimental works enabled the elaboration of various scenarios for Life Cycle Analysis (LCA). The LCA showed that the environmental impact of the system is highly dependent on the recovery rate of the magnetic particles. The absolute impact on climate change varied significantly among the scenarios studied and the recovery rates. The results support the hypothesis that chelation specificity, magnetic separation and bead recovery should be optimized to specific targets and applications.
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| 7. |
- Bonini, M., et al.
(författare)
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Adsorption of Amino Acids and Glutamic Acid-Based Surfactants on Imogolite Clays
- 2017
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 33:9, s. 2411-2419
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Tidskriftsartikel (refereegranskat)abstract
- Aluminum oxide surfaces are of utmost interest in different biotech applications, in particular for their use as adjuvants (i.e., booster of the immune response against infectious agents in vaccines production). In this framework, imogolite clays combine the chemical flexibility of an exposed alumina surface with 1D nanostructure. This work reports on the interaction between amino acids and imogolite, using turbidimetry, zeta-potential measurements, and Fourier transform infrared spectroscopy as main characterization tools. Amino acids with different side chain functional groups were investigated, showing that glutamic acid (Glu) has the strongest affinity for the imogolite surface. This was exploited to prepare a composite material made of a synthetic surfactant bearing a Glu polar head and a hydrophobic C-12 alkyl tail, adsorbed onto the surface of imogolite. The adsorption of a model drug (rhodamine B isothiocyanate) by the hybrid was evaluated both in water and in physiological saline conditions. The findings of this paper suggest that the combination between the glutamate headgroup and imogolite represents a promising platform for the fabrication of hybrid nanostructures with tailored functionalities.
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| 8. |
- Bordes, Romain, 1981, et al.
(författare)
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Adsorption of Dianionic Surfactants Based on Amino Acids at Different Surfaces Studied by QCM-D and SPR
- 2010
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 26:13, s. 10935-10942
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of three dicarboxylic amino acid-based surfactants, disodium N-lauroylaminomalonate, disodium N-lauroylaspartate, and disodium N-lauroylglutamate, has been studied by surface plasmon resonance (SPR) and the quartz crystal microbalance with dissipation monitoring (QCM-D). These surfactants have high cmc values, which means that the unimer concentration is high at the plateau value of adsorption. This gives rise to a considerable "bulk effect", which must be deducted from the observed value in order to obtain the true value of the adsorbed amount. In this article, we show how this can be done for the QCM-D technique. Adsorption is studied on silica, gold, gold hydrophobized by a self-assembled layer of an alkane thiol, and hydroxyapatite. Adsorption on hydroxyapatite differs very much among the three surfactants, with the aspartate derivative giving the strongest and the glutamate giving the weakest adsorption. This difference is explained as the difference in ability of the dicarboxylic amphiphiles to chelate calcium in the crystal lattice.
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| 9. |
- Bordes, Romain, 1981, et al.
(författare)
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Amino acid-based surfactants
- 2009
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Ingår i: Encyclopedia of Surface and Colloid Science. ; , s. 1-17
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Bordes, Romain, 1981, et al.
(författare)
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Amino acid-based surfactants - Do they deserve more attention?
- 2015
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Ingår i: Advances in Colloid and Interface Science. - : Elsevier BV. - 0001-8686. ; 222, s. 79-91
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Forskningsöversikt (refereegranskat)abstract
- The 20 standard amino acids (together with a few more that are not used in the biosynthesis of proteins) constitute a versatile tool box for synthesis of surfactants. Anionic, cationic and zwitterionic amphiphiles can be prepared and surfactants with several functional groups can be obtained by the proper choice of starting amino acid. This review gives examples of procedures used for preparation and discusses important physicochemical properties of the amphiphiles and how these can be taken advantage of for various applications. Micelles with a chiral surface can be obtained by self-assembly of enantiomerically pure surfactants and such supramolecular chirality can be utilized for asymmetric organic synthesis and for preparation of mesoporous materials with chiral pores. Surfactants based on amino acids with two carboxyl groups are effective chelating agents and can be used as collectors in mineral ore flotation. A surfactant based on cysteine readily oxidizes into the corresponding cystine compound, which can be regarded as a gemini surfactant. The facile and reversible cysteine-cystine transformation has been taken advantage of in the design of a switchable surfactant. A very attractive aspect of surfactants based on amino acids is that the polar head-group is entirely natural and that the linkage to the hydrophobic tail, which is often an ester or an amide bond, is easily cleaved. The rate of degradation can be tailored by the structure of the amphiphile. The ester linkage in betaine ester surfactants is particularly susceptible to alkaline hydrolysis and this surfactant type can be used as a biocide with short-lived action. This paper is not intended as a full review on the topic. Instead it highlights concepts that are unique to amino acid-based surfactants and that we believe can have practical implications.
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