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Baiesi M, Iubini S, Orlandini E. The rise and fall of branching: A slowing down mechanism in relaxing wormlike micellar networks. J Chem Phys 2021; 155:214905. [PMID: 34879666 DOI: 10.1063/5.0072374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A mean-field kinetic model suggests that the relaxation dynamics of wormlike micellar networks is a long and complex process due to the problem of reducing the number of free end-caps (or dangling ends) while also reaching an equilibrium level of branching after an earlier overgrowth. The model is validated against mesoscopic molecular dynamics simulations and is based on kinetic equations accounting for scission and synthesis processes of blobs of surfactants. A long relaxation time scale is reached with both thermal quenches and small perturbations of the system. The scaling of this relaxation time is exponential with the free energy of an end cap and with the branching free energy. We argue that the subtle end-recombination dynamics might yield effects that are difficult to detect in rheology experiments, with possible underestimates of the typical time scales of viscoelastic fluids.
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Affiliation(s)
- Marco Baiesi
- Dipartimento di Fisica e Astronomia, Università di Padova, via Marzolo 8, I-35131 Padova, Italy
| | - Stefano Iubini
- Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - Enzo Orlandini
- Dipartimento di Fisica e Astronomia, Università di Padova, via Marzolo 8, I-35131 Padova, Italy
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Patil R, Ray D, Aswal VK, Bussy C, Bahadur P, Tiwari S. Adsorption of P103 Nanoaggregates on Graphene Oxide Nanosheets: Role of Electrostatic Forces in Improving Nanosheet Dispersion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:867-873. [PMID: 33400877 DOI: 10.1021/acs.langmuir.0c03206] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Graphene oxide (GO) nanosheet suspension is not stable in physiological ionic fluids. To improve stability, surfactants such as Pluronic 103 (P103) have been tested. Going further, this work investigated whether conferring positive surface charge to the surfactant may improve the adsorption ability of P103 micelles on GO sheets. Positive charge on the surfactant was induced by adding dodecyltrimethylammonium bromide (DTAB, a cationic surfactant) in P103 micelles. Subsequent changes in aggregation parameters were investigated through dynamic light scattering and small-angle neutron scattering studies. DTAB incorporation was accompanied by a steady increase in the ζ potential and mixed micelle formation. At high surface charge density, the interaction between adjacent head groups was distorted, which led to dissociation of mixed micelles. Structural developments during the adsorption of mixed micelles on the sheet surface (mass fractal formation) were monitored in terms of changes in the scattering features of aggregates. These fractals emerged as a result of electrostatic interactions. Our observations point toward the existence of small-sized building blocks at low DTAB concentration (≤4 mM). With a superior adsorption, mixed micelles are expected to occupy the intersheet space and maintain a hydration layer. However, at a higher DTAB concentration (≥10 mM), micelles dissociate to produce DTAB-rich unimers and P103-rich loose aggregates. At this point, sheets tend to aggregate in the solvent, regardless of fractal formation.
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Affiliation(s)
- Rahul Patil
- Maliba Pharmacy College, UKA Tarsadia University, Gopal-Vidyanagar Campus, Surat 394350, India
| | - Debes Ray
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Vinod K Aswal
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Cyrill Bussy
- Nanomedicine Lab, School of Biological Sciences, and Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine & Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PR, U.K
- National Graphene Institute, The University of Manchester, Manchester M13 9PR, U.K
| | - Pratap Bahadur
- Department of Chemistry, Veer Narmad South Gujarat University, Surat 395007, India
| | - Sanjay Tiwari
- Maliba Pharmacy College, UKA Tarsadia University, Gopal-Vidyanagar Campus, Surat 394350, India
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3
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Nanoengineering of Gold Nanoparticles: Green Synthesis, Characterization, and Applications. CRYSTALS 2019. [DOI: 10.3390/cryst9120612] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The fundamental aspects of the manufacturing of gold nanoparticles (AuNPs) are discussed in this review. In particular, attention is devoted to the development of a simple and versatile method for the preparation of these nanoparticles. Eco-friendly synthetic routes, such as wet chemistry and biosynthesis with the aid of polymers, are of particular interest. Polymers can act as reducing and/or capping agents, or as soft templates leading to hybrid nanomaterials. This methodology allows control of the synthesis and stability of nanomaterials with novel properties. Thus, this review focus on a fundamental study of AuNPs properties and different techniques to characterize them, e.g., Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), UV-Visible spectroscopy, Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy, Small-angle X-Ray Scattering (SAXS), and rheology. Recently, AuNPs obtained by “green” synthesis have been applied in catalysis, in medicine, and as antibacterials, sensors, among others.
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Heinzelmann G, Figueiredo W. Confinement effects on micellar systems with a hydrogen-bonding solvent. J Chem Phys 2017; 145:164902. [PMID: 27802639 DOI: 10.1063/1.4965817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Space confinement greatly influences the properties of liquids, such as their viscosity and capillary critical point. For aqueous solutions of amphiphiles, this effect is extended to the mobility and micellization properties of these molecules, changing important characteristics of micellar solutions such as the critical micelle concentration (CMC). In the present work, we use a lattice Monte Carlo model, which allows for orientational freedom and hydrogen-bond formation for the water molecules, to investigate confinement effects on a solution of surfactants limited by two parallel walls perpendicular to one of the Cartesian axes. This configuration aims to reproduce a small pore, and walls with a hydrophilic or hydrophobic character are studied. We find that, for hydrophilic walls, there is an increase in the value of the CMC for small pores, caused by space confinement effects and also by the interactions of the amphiphile polar heads with the walls. Micelles are able to adhere to the walls as a whole, and their shape shows little change compared to micelles in the bulk solution. Hydrophobic walls show a more dramatic effect on the properties of the solution, arising mainly from the strong adsorption of the amphiphile tails on the walls, driven by the hydrophobic effect. The process of adsorption of amphiphiles with increasing concentration shows a behavior very similar to the one observed in experiments and simulations of such systems. Micelles adsorbed to the hydrophobic walls also show significant changes in their moments of inertia compared to the bulk ones, which is attributed to the formation of half-micelles that have their tails attached to the walls and the polar heads facing the solution. We extend our analysis to the change in the hydrogen-bonding properties of the solvent caused by the confinement, and how that is directly related to the number of free amphiphiles in our system for different pore sizes. Finally, we test different surfactant sizes and how they affect the micellar shape for different concentrations.
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Affiliation(s)
- G Heinzelmann
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina, Brazil
| | - W Figueiredo
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina, Brazil
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The origin of anomalous positive heat capacity change upon micellization of Pluronic triblock copolymer F108 in aqueous solutions: Effect of PEO-PPO diblock impurities. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2016.08.070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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6
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Arranja A, Waton G, Schosseler F, Mendes E. Lack of a unique kinetic pathway in the growth and decay of Pluronic micelles. SOFT MATTER 2016; 12:769-778. [PMID: 26523415 DOI: 10.1039/c5sm02353j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report kinetic experiments on dilute brine solutions of P84, P94 and P104 Pluronic copolymer micelles. The growth and the decay of micelles after temperature steps are measured by non-standard time resolved multi-angle photon correlation spectroscopy. Several concurrent mechanisms are at work during the very slow equilibration of solutions, namely insertion/expulsion of unimers, aggregation/dissociation of micellar aggregates, and fusion/budding of micellar aggregates. Their relative rates determine both the kinetic pathways and the morphologies of the micellar assemblies, which depend markedly on modest changes in the copolymer molecular weight. For the typical Pluronic copolymers investigated here, none of these elementary processes can be neglected if the resulting morphology is to be explained. This feature imposes multiple kinetic behaviours where growth and decay of Pluronic micelles become strongly dependent on the thermal history. We point out to some possible shortcomings in the studies of micellar growth kinetics by light scattering techniques. Extensive time-resolved multiangle measurements are a prerequisite for avoiding these pitfalls.
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Affiliation(s)
- Alexandra Arranja
- Institut Charles Sadron, University of Strasbourg, CNRS UPR 22, 23 rue du Loess, 67034 Strasbourg Cedex 2, France.
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Heinzelmann G, Seide P, Figueiredo W. Dynamics of micelle formation from temperature-jump Monte Carlo simulations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:052305. [PMID: 26651693 DOI: 10.1103/physreve.92.052305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Indexed: 06/05/2023]
Abstract
In the present work we perform temperature jumps in a surfactant solution by means of Monte Carlo simulations, investigating the dynamics of micelle formation. We use a lattice model that allows orientational freedom and hydrogen bonding for solvent molecules, which can make a connection between the different time scales of hydrogen bond formation and amphiphilic aggregation. When we perform a large jump between a high-temperature nonmicellized state and a micellized state, there is strong hysteresis between the heating and cooling processes, the latter showing the formation of premicelles that act as nucleation centers for the assembly of larger aggregates and the former is a drive for dissociation of the existing aggregates. Hysteresis is not seen when we perform a small jump between two states that can be both micellized or nonmicellized. Looking for a more detailed analysis of the hydrophobic effect that drives aggregation, we compare the time evolution of the solvent hydrogen bonds in our system close and far from micelles and how that is affected by the formation of large clusters at low temperatures. We find a strong connection between them, with the total number of hydrogen bonds in the system always increasing when micelles are formed. To gain insights into the mechanism of premicellar formation and growth, we measure the lifetime of micellized amphiphiles as a function of the aggregate size and the stage of the aggregation process. Our results indicate that the premicelles are always unstable, quickly exchanging amphiphiles with the solution due to their low probabilty in equilibrium. Furthermore, we find that the stability of individual surfactants in micelles increases with the aggregate size, with the lifetime of amphiphiles in large micelles being as much as 35 times longer than in the case of the unstable premicellar region.
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Affiliation(s)
- G Heinzelmann
- Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, Santa Catarina, Brazil
| | - P Seide
- Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, Santa Catarina, Brazil
| | - W Figueiredo
- Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, Santa Catarina, Brazil
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9
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Stress-Temperature Effects on Transitions in PEO17PPO60PEO17 Triblock Copolymer Micellar Solutions. J SURFACTANTS DETERG 2013. [DOI: 10.1007/s11743-013-1525-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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10
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Xu L, Zhang Z, Wang F, Xie D, Yang S, Wang T, Feng L, Chu C. Synthesis, characterization, and self-assembly of linear poly(ethylene oxide)-block–poly(propylene oxide)-block–poly(ε-caprolactone) (PEO–PPO–PCL) copolymers. J Colloid Interface Sci 2013; 393:174-81. [DOI: 10.1016/j.jcis.2012.10.051] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Revised: 10/21/2012] [Accepted: 10/24/2012] [Indexed: 01/11/2023]
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11
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Rharbi Y. Fusion and Fragmentation Dynamics at Equilibrium in Triblock Copolymer Micelles. Macromolecules 2012. [DOI: 10.1021/ma3018298] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Y. Rharbi
- Laboratoire de Rhéologie
et procédés, CNRS/UJF/INPG, UMR 5520, B.P.53, F-38041 Grenoble Cedex
9, France
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12
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Heinzelmann G, Figueiredo W, Girardi M. Micellar dynamics and water–water hydrogen-bonding from temperature-jump Monte Carlo simulations. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.09.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Landazuri G, Fernandez VVA, Soltero JFA, Rharbi Y. Kinetics of the sphere-to-rod like micelle transition in a pluronic triblock copolymer. J Phys Chem B 2012; 116:11720-7. [PMID: 22934621 DOI: 10.1021/jp3009089] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The kinetics of the sphere-to-rod transition was studied in aqueous micelle solutions of triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) pluronic P103 (PEO(17)PPO(60)PEO(17)). This transition was triggered by a temperature jump from the sphere phase to the rod phase and monitored with dynamic light scattering. The combination of the scattering intensity and the hydrodynamic radius were used to show that the micelles grow steadily as rods throughout the growth process. The transition was found to exhibit a single exponential behavior even in the case of large deviations from equilibrium. The linear increase in the decay rate with increasing copolymer concentration shows that the transition is dominated by a mechanism involving fusion and fragmentation of proper micelles. The decays of the sphere-to-rod transition were simulated for two pathways: random fusion fragmentation and successive addition of spherical micelles to rods. We show that micelle growth most likely occurs via random fusion-fragmentation. The second order rate constant for fusion and the fragmentation rate are calculated for the case of random fusion-fragmentation.
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Affiliation(s)
- Gabriel Landazuri
- Laboratoire de Rhéologie, UJF/INPG/CNRS, UMR 5520, B.P.53, F-38041 Grenoble Cedex 9, France
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de Moraes J, Figueiredo W. Temporal evolution of micellar aggregates in the temperature jump experiments. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.03.070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Jia L, Guo C, Yang L, Xiang J, Tang Y, Liu C, Liu H. Mechanism of PEO–PPO–PEO micellization in aqueous solutions studied by two-dimensional correlation FTIR spectroscopy. J Colloid Interface Sci 2010; 345:332-7. [DOI: 10.1016/j.jcis.2010.01.060] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 01/18/2010] [Accepted: 01/22/2010] [Indexed: 11/17/2022]
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16
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Kadam Y, Ganguly R, Kumbhakar M, Aswal VK, Hassan PA, Bahadur P. Time Dependent Sphere-to-Rod Growth of the Pluronic Micelles: Investigating the Role of Core and Corona Solvation in Determining the Micellar Growth Rate. J Phys Chem B 2009; 113:16296-302. [DOI: 10.1021/jp9036974] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Y. Kadam
- Department of Chemistry, V.N. South Gujarat University, Surat 395007, Chemistry Division, Radiation & Photochemistry Division, Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
| | - R. Ganguly
- Department of Chemistry, V.N. South Gujarat University, Surat 395007, Chemistry Division, Radiation & Photochemistry Division, Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
| | - M. Kumbhakar
- Department of Chemistry, V.N. South Gujarat University, Surat 395007, Chemistry Division, Radiation & Photochemistry Division, Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
| | - V. K. Aswal
- Department of Chemistry, V.N. South Gujarat University, Surat 395007, Chemistry Division, Radiation & Photochemistry Division, Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
| | - P. A. Hassan
- Department of Chemistry, V.N. South Gujarat University, Surat 395007, Chemistry Division, Radiation & Photochemistry Division, Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
| | - P. Bahadur
- Department of Chemistry, V.N. South Gujarat University, Surat 395007, Chemistry Division, Radiation & Photochemistry Division, Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
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