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Olszewski M, Hu X, Lin TC, Matyjaszewski K, Lebedeva N, Taylor P. Oscillatory and Relaxation Study of the Interfacial Rheology of Star Polymers with Low-Grafting-Density PEO Arms and Hydrophobic Poly(divinylbenzene) Cores. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37216597 DOI: 10.1021/acs.langmuir.3c00557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Star polymers have been gaining interest due to their tunable properties. They have been used as effective stabilizers for Pickering emulsions. Herein, star polymers were synthesized via activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP). Poly(ethylene oxide) (PEO) with terminal α-bromoisobutyrate ATRP functionality was used as a macroinitiator and divinylbenzene as a crosslinker for the arm-first star synthesis. Stars with PEO arms with a molar mass of either 2 or 5 kDa had a relatively low density of grafted chains, i.e., ca. 0.25 chain/nm2. The properties of PEO stars adsorbed at oil-water interfaces were investigated using interfacial tension and interfacial rheology. The magnitude of interfacial tensions at oil-water interfaces depends on the nature of the oil phase, being lower at the m-xylene/water interface than at the n-dodecane/water interface. Small differences were observed for stars with different molecular weights of PEO arms. The overall behavior of PEO stars adsorbed at an interface can be considered as an intermediate between a particle and a linear/branched polymer. Obtained results offer an important insight into the interfacial rheology of PEO star polymers in the context of their application as stabilizers for Pickering emulsions.
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Affiliation(s)
- Mateusz Olszewski
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Xiaolei Hu
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Ting-Chih Lin
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Krzysztof Matyjaszewski
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Natalia Lebedeva
- Syngenta Crop Protection, LLC, Greensboro, North Carolina 27409, United States
| | - Philip Taylor
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, U.K
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Masrat R, Dar AA. Interaction of HPC with CTAB and Tween 40 at Water/Air and Water/Soya Oil Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:1145-1158. [PMID: 36622144 DOI: 10.1021/acs.langmuir.2c02902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The bulk and interfacial shear rheological behavior of aqueous solutions of biocompatible polymer HPC has been investigated in the presence of cationic CTAB and nonionic Tween 40 having the same chain length but different head groups. Steady-state bulk experiments depict two distinct regions in the rheogram (Newtonian followed by pseudoplastic). Dynamic experiments suggest that the stability of HPC hydrogels decreases with the increase in surfactant concentration. Interfacial steady shear tests of 2D monolayers of 1 wt % HPC and 1 wt % HPC with varying concentrations of Tween 40/CTAB show a non-Newtonian dilatant behavior at the solution-air interface. However, two distinct dilatant regions separated by a Newtonian region were observed for the same films at the solution-soya oil interface. The strength of films formed at the two interfaces decreases with the increase of surfactant concentration as observed from oscillatory interfacial tests. HPC interacts more strongly with CTAB than Tween 40 both in bulk as well as at the interfaces studied.
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Affiliation(s)
- Rohi Masrat
- Department of Chemistry, National Institute of Technology, Srinagar, Kashmir, 190006JK, India
| | - Aijaz Ahmad Dar
- Soft Matter Research Group, Physical Chemistry Section, Department of Chemistry, University of Kashmir, Srinagar190006JK, India
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Ciutara CO, Barman S, Iasella S, Huang B, Zasadzinski JA. Dilatational and shear rheology of soluble and insoluble monolayers with a Langmuir trough. J Colloid Interface Sci 2023; 629:125-135. [PMID: 36063630 PMCID: PMC10038177 DOI: 10.1016/j.jcis.2022.08.051] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/31/2022] [Accepted: 08/09/2022] [Indexed: 10/15/2022]
Abstract
HYPOTHESIS The surface dilatational and shear moduli of surfactant and protein interfacial layers can be derived from surface pressures measured with a Wilhelmy plate parallel, ΔΠpar and perpendicular ΔΠperp to the barriers in a Langmuir trough. EXPERIMENTAL Applying area oscillations, A0+ ΔAeiωt, in a rectangular Langmuir trough induces changes in surface pressure, ΔΠpar and ΔΠperp for monolayers of soluble palmitoyl-lysophosphatidylcholine (LysoPC), insoluble dipalmitoylphosphatidylcholine (DPPC), and the protein β-lactoglobulin to evaluate Es∗+Gs∗=A0ΔΠparΔA and Es∗-Gs∗=A0ΔΠperpΔA. Gs∗ was independently measured with a double-wall ring apparatus (DWR) and Es∗ by area oscillations of hemispherical bubbles in a capillary pressure microtensiometer (CPM) and the results were compared to the trough measurements. FINDINGS For LysoPC and DPPC, A0ΔΠparΔA≅A0ΔΠperpΔA meaning Es∗≫Gs∗ and Es∗≅A0ΔΠparΔA≅A0ΔΠperpΔA. Trough values for Es∗ were quantitatively similar to CPM when corrected for interfacial curvature. DWR showed G∗ was 4 orders of magnitude smaller than Es∗ for both LysoPC and DPPC. For β-lactoglobulin films, A0ΔΠparΔA>A0ΔΠperpΔA and Es∗ and Gs∗ were in qualitative agreement with independent CPM and DWR measurements. For β-lactoglobulin, both Es∗ and Gs∗ varied with film age and history on the trough, suggesting the evolution of the protein structure.
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Affiliation(s)
- Clara O Ciutara
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Sourav Barman
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Steven Iasella
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Boxun Huang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Joseph A Zasadzinski
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
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Ritacco HA. Polyelectrolyte/Surfactant Mixtures: A Pathway to Smart Foams. ACS OMEGA 2022; 7:36117-36136. [PMID: 36278099 PMCID: PMC9583308 DOI: 10.1021/acsomega.2c05739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 09/26/2022] [Indexed: 05/10/2023]
Abstract
This review deals with liquid foams stabilized by polyelectrolyte/surfactant (PS) complexes in aqueous solution. It briefly reviews all the important aspects of foam physics at several scales, from interfaces to macroscopic foams, needed to understand the basics of these complex systems, focusing on those particular aspects of foams stabilized by PS mixtures. The final section includes a few examples of smart foams based on PS complexes that have been reported recently in the literature. These PS complexes open an opportunity to develop new intelligent dispersed materials with potential in many fields, such as oil industry, environmental remediation, and pharmaceutical industry, among others. However, there is much work to be done to understand the mechanism involved in the stabilization of foams with PS complexes. Understanding those underlying mechanisms is vital to successfully formulate smart systems. This review is written in the hope of stimulating further work in the physics of PS foams and, particularly, in the search for responsive foams based on polymer-surfactant mixtures.
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Chan DHH, Hunter SJ, Neal TJ, Lindsay C, Taylor P, Armes SP. Adsorption of sterically-stabilized diblock copolymer nanoparticles at the oil-water interface: effect of charged end-groups on interfacial rheology. SOFT MATTER 2022; 18:6757-6770. [PMID: 36040127 DOI: 10.1039/d2sm00835a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The RAFT aqueous emulsion polymerization of either methyl methacrylate (MMA) or benzyl methacrylate (BzMA) is conducted at 70 °C using poly(glycerol monomethacrylate) (PGMA) as a water-soluble precursor to produce sterically-stabilized diblock copolymer nanoparticles of approximately 30 nm diameter. Carboxylic acid- or morpholine-functional RAFT agents are employed to confer anionic or cationic functionality at the ends of the PGMA stabilizer chains, with a neutral RAFT agent being used as a control. Thus the electrophoretic footprint of such minimally-charged model nanoparticles can be adjusted simply by varying the solution pH. Giant (mm-sized) aqueous droplets containing such nanoparticles are then grown within a continuous phase of n-dodecane and a series of interfacial rheology measurements are conducted. The interfacial tension between the aqueous phase and n-dodecane is strongly dependent on the charge of the terminal group on the stabilizer chains. More specifically, neutral nanoparticles produce a significantly lower interfacial tension than either cationic or anionic nanoparticles. Moreover, adsorption of neutral nanoparticles at the n-dodecane-water interface produces higher interfacial elastic moduli than that observed for charged nanoparticles. This is because neutral nanoparticles can adsorb at much higher surface packing densities owing to the absence of electrostatic repulsive forces in this case.
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Affiliation(s)
- Derek H H Chan
- Dainton Building, Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, South Yorkshire, S3 7HF, UK.
| | - Saul J Hunter
- Dainton Building, Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, South Yorkshire, S3 7HF, UK.
| | - Thomas J Neal
- Dainton Building, Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, South Yorkshire, S3 7HF, UK.
| | - Christopher Lindsay
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6EY, UK.
| | - Philip Taylor
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6EY, UK.
| | - Steven P Armes
- Dainton Building, Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, South Yorkshire, S3 7HF, UK.
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Kurapati R, Natarajan U. New insights into adsorption structure and hydration of polymer at oil-water interface obtained by molecular dynamics simulations: Isotactic poly(methacrylic acid). POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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7
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Thermodynamic properties and morphology of 2D NBR/PEG-PPG-PEG networks. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Vaillard AS, El Haitami A, Dreier LB, Fontaine P, Cousin F, Gutfreund P, Goldmann M, Backus EHG, Cantin S. Vertically Heterogeneous 2D Semi-Interpenetrating Networks Based on Cellulose Acetate and Cross-Linked Polybutadiene. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2538-2549. [PMID: 35171621 DOI: 10.1021/acs.langmuir.1c03084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
This work reports the feasibility of polybutadiene (PB) cross-linking under UV irradiation in the presence of a linear polymer, cellulose acetate (CA), to form semi-interpenetrating polymer networks at the air-water interface. The thermodynamic properties and the morphology of two-dimensional (2D) CA/PB blends are investigated after UV irradiation and for a wide range of CA volume fractions. A contraction of the mixed Langmuir films is observed independent of the composition, in agreement with that recorded for the individual PB monolayer after cross-linking. The PB network formation is demonstrated by in situ sum-frequency generation spectroscopy on the equivolumic CA/PB mixed film. From Brewster angle microscopy observations, the PB network synthesis does not induce any morphology change at the mesoscopic scale, and all of the mixed films remain homogeneous laterally. In situ neutron reflectometry is used to probe the effect of PB cross-linking on the vertical structure of CA/PB mixed films. For all studied compositions, significant thickening of the films is evidenced, consistent with their contraction ratio. This thickening is accompanied by a partial expulsion of the PB toward the film-air interface, which is attributed to the hydrophobic character of the PB. This phenomenon is stronger for films rich in PB. In particular, the structure of the PB-rich film undergoes a transition from vertically homogeneous to inhomogeneous along the depth. 2D semi-interpenetrating polymer networks can thus be synthesized at the air-water interface with a morphology that is strongly influenced by the polymer-polymer and polymer-environment interactions.
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Affiliation(s)
| | | | - Lisa B Dreier
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Philippe Fontaine
- Synchrotron SOLEIL, L'Orme des Merisiers, 91192 Gif sur Yvette Cedex, France
| | - Fabrice Cousin
- Laboratoire Léon Brillouin, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | | | - Michel Goldmann
- Synchrotron SOLEIL, L'Orme des Merisiers, 91192 Gif sur Yvette Cedex, France
- Institut des NanoSciences de Paris, Sorbonne Université, 75252 Paris Cedex 05, France
- Faculté des Sciences Fondamentales et Biomédicales, Université de Paris, 75006 Paris, France
| | - Ellen H G Backus
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Department of Physical Chemistry, University of Vienna, Währinger Strasse 42, A-1090 Vienna, Austria
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9
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In situ determination of the structure and composition of Langmuir monolayers at the air/water interface by neutron and X-ray reflectivity and ellipsometry. Adv Colloid Interface Sci 2021; 293:102434. [PMID: 34022749 DOI: 10.1016/j.cis.2021.102434] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 02/07/2023]
Abstract
This review focuses on the description of the structure and composition of a variety of Langmuir monolayers (LMs) deposited at the air/water interface by using ellipsometry, Brewster Angle microscopy and scattering techniques, mainly neutron and X-ray reflectometry. Since the first experiment done by Angels Pockels with a homemade trough in her home kitchen until today, LMs of different materials have been extensively studied providing not only relevant model systems in biology, physics and chemistry but also precursors of novel materials via their deposition on solid substrates. There is a vast amount of surface-active materials that can form LMs and, therefore, far from a revision of the state-of-the-art, we will emphasize here: (i) some fundamental aspects to understand the physics behind the molecular deposition at the air/water interface; (ii) the advantages in using in situ techniques, such as reflectometry or ellipsometry, to resolve the interfacial architecture and conformation of molecular films; and, finally, (iii) a summary of several systems that have certain interest from the experimental or conceptual point of view. Concretely, we will report here advances in polymers confined to interfaces and surfactants, from fatty acids and phospholipids monolayers to more unconventional ones such as graphene oxide.
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10
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Kale SK, Cope AJ, Goggin DM, Samaniuk JR. A miniaturized radial Langmuir trough for simultaneous dilatational deformation and interfacial microscopy. J Colloid Interface Sci 2021; 582:1085-1098. [PMID: 32932179 DOI: 10.1016/j.jcis.2020.08.053] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 12/29/2022]
Abstract
INNOVATION Interfacial rheological properties of complex fluid-fluid interfaces are strongly influenced by the film microstructure. Experimental investigations for correlating interfacial morphology and rheology are notoriously challenging. A miniaturized radial Langmuir trough was developed to study complex fluid-fluid interfaces under purely dilatational deformations that operates in tandem with a conventional inverted microscope for simultaneous interfacial visualization. EXPERIMENTS Two materials were investigated at an air-water interface: poly(tert-butyl methacrylate) (PtBMA) and dipalmitoylphosphatidylcholine (DPPC). Surface pressure measurements made in the radial Langmuir trough were compared with a commercial rectangular Langmuir trough. Interfacial in situ visualization for each material was performed during the compression cycle in the radial trough. Challenges associated with the small size of the radial Langmuir trough, such as the influence of capillary deformation on the measured surface pressure, are also quantified. FINDINGS Measured surface pressures between the newly developed radial trough and the rectangular Langmuir trough compare well. Micrographs obtained in the radial Langmuir trough were used to obtain film properties such as Young's modulus. The new advance in colloid and interface science is the ability to capture structure-property relationships of planar interfaces using microscopy and purely dilatational deformation. This will advance the development of constitutive modeling of complex fluid-fluid interfaces.
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Affiliation(s)
- Shalaka K Kale
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - Andrew J Cope
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - David M Goggin
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - Joseph R Samaniuk
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, USA
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11
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Hsieh TL, Martinez MR, Garoff S, Matyjaszewski K, Tilton RD. Interfacial dilatational rheology as a bridge to connect amphiphilic heterografted bottlebrush copolymer architecture to emulsifying efficiency. J Colloid Interface Sci 2021; 581:135-147. [DOI: 10.1016/j.jcis.2020.07.063] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/12/2020] [Accepted: 07/13/2020] [Indexed: 11/29/2022]
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12
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da Rocha Rodrigues R, da Silva RLCG, Caseli L, Péres LO. Conjugated polymers as Langmuir and Langmuir-Blodgett films: Challenges and applications in nanostructured devices. Adv Colloid Interface Sci 2020; 285:102277. [PMID: 32992077 DOI: 10.1016/j.cis.2020.102277] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/14/2020] [Accepted: 09/20/2020] [Indexed: 12/01/2022]
Abstract
Initially developed for classic systems composed of fatty acids and phospholipids, the Langmuir and Langmuir-Blodgett (LB) techniques allow the fabrication of nanometer-scale devices at self-assembly interfaces with high control over the thickness and molecular architecture. Their application in the research and production of new plastic materials has grown considerably over the past few decades due to the efficiency of conjugated polymers (CPs) for the production of light-emitting diodes, flexible displays, solar cells, and other photoelectronic devices. The structuring of polymers at different interfaces is not trivial as this class of macromolecules can undergo through different processes of folding/unfolding, which hinders the formation of stable Langmuir monolayers and, consequently, the production of Langmuir-Blodgett films. With these ideas in mind, the present article aims to review a series of elements related to the formation of stable Langmuir and Langmuir-Blodgett films of CPs, especially those based on poly(phenylene vinylene)s, polyfluorenes, and polythiophenes. This review is divided into two parts where we first discuss the formation of neat CP films, and then the strategies for the formation of stable CP films based on the co-immobilization with fatty acids, other polymers, and enzymes as mixed films.
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Affiliation(s)
- Rebeca da Rocha Rodrigues
- Laboratory of Hybrid Materials, Department of Chemistry, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | | | - Luciano Caseli
- Laboratory of Hybrid Materials, Department of Chemistry, Federal University of São Paulo, Diadema, São Paulo, Brazil.
| | - Laura Oliveira Péres
- Laboratory of Hybrid Materials, Department of Chemistry, Federal University of São Paulo, Diadema, São Paulo, Brazil
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13
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Hutzler S, Dunne FF, Kraynik AM, Weaire D. The energy of fcc and hcp foams. SOFT MATTER 2020; 16:8262-8271. [PMID: 32935729 DOI: 10.1039/d0sm00820f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We present Surface Evolver evaluations of the difference in energy between face-centred cubic (fcc) and hexagonal close-packed (hcp) foams in the usual idealized model, for liquid fractions ranging from the dry to the wet limit. The difference vanishes in both limits, and favours hcp for all intermediate liquid fractions, as has been proven. The maximum relative energy difference is very small, of the order of 10-5. The asymptotic dependence on liquid fraction is non-analytic in both limits: we present explicit expressions in both cases, derived from first principles. They have been obtained from identifying node interactions (dry limit) and contact interactions (wet limit) as the respective sources for energy differences between fcc and hcp. The wet limit is well described by Morse-Witten theory which has proven to be very powerful for the analytic computation of the surface energy of slightly deformed bubbles.
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Affiliation(s)
- S Hutzler
- School of Physics, Trinity College Dublin, The University of Dublin, Ireland.
| | - F F Dunne
- School of Physics, Trinity College Dublin, The University of Dublin, Ireland.
| | - A M Kraynik
- School of Physics, Trinity College Dublin, The University of Dublin, Ireland. and Retired from Sandia National Laboratories, Albuquerque, USA
| | - D Weaire
- School of Physics, Trinity College Dublin, The University of Dublin, Ireland.
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Boadi FO, Zhang J, Yu X, Bhatia S, Sampson NS. Alternating Ring-Opening Metathesis Polymerization Provides Easy Access to Functional and Fully Degradable Polymers. Macromolecules 2020; 53:5857-5868. [PMID: 33776145 PMCID: PMC7993654 DOI: 10.1021/acs.macromol.0c01051] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Polymers with hydrolyzable groups in their backbones have numerous potential applications in biomedicine, lithography, energy storage and electronics. In this study, acetal and ester functionalities were incorporated into the backbones of copolymers by means of alternating ring-opening metathesis polymerization catalyzed by third-generation Grubbs ruthenium catalyst. Specifically, combining large-ring (7-10 atoms) cyclic acetal or lactone monomers with bicyclo[4.2.0]oct-1(8)-ene-8-carboxamide monomers provided perfectly alternating copolymers with acetal or ester functionality in the backbones and low to moderate molecular weight distribution (Đ M = 1.2-1.6). Copolymers containing ester and acetal backbones hydrolyzed to significant extent under basic condition (pH 13) and acidic conditions (pH ≤ 5) respectively to yield the expected by-products within 30 hours at moderate temperature. Unlike the copolymer with all-carbon backbone, copolymers with heteroatom-containing backbone exhibited viscoelastic behavior with crossover frequency which decreases as the size of the R group on the acetal increases. In contrast, the glass transition temperature (T g) decreases as the size of the R group decreases. The rate of hydrolysis of the acetal copolymers was also dependent on the R group. Thus, ruthenium-catalyzed alternating ring-opening metathesis copolymerization provides heterofunctional copolymers whose degradation rates, glass transition temperatures, and viscoelastic moduli can be controlled.
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Affiliation(s)
- Francis O. Boadi
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400
| | - Jingling Zhang
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY 11794-2275
| | - Xiaoxi Yu
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400
| | - Surita Bhatia
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400
| | - Nicole S Sampson
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400
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15
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Physical properties of mucilage polysaccharides from Dioscorea opposita Thunb. Food Chem 2020; 311:126039. [DOI: 10.1016/j.foodchem.2019.126039] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/21/2019] [Accepted: 12/06/2019] [Indexed: 11/19/2022]
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16
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Masrat R, Shah RA, Lone MS, Ashraf U, Afzal S, Rather GM, Dar AA. Comparison between the interfacial and bulk rheology of sodium carboxymethylcellulose in the presence of cationic and non-ionic surfactants. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112477] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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17
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Tarazona NA, Machatschek R, Lendlein A. Unraveling the Interplay between Abiotic Hydrolytic Degradation and Crystallization of Bacterial Polyesters Comprising Short and Medium Side-Chain-Length Polyhydroxyalkanoates. Biomacromolecules 2020; 21:761-771. [PMID: 31841314 DOI: 10.1021/acs.biomac.9b01458] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Polyhydroxyalkanoates (PHAs) have attracted attention as degradable (co)polyesters which can be produced by microorganisms with variations in the side chain. This structural variation influences not only the thermomechanical properties of the material but also its degradation behavior. Here, we used Langmuir monolayers at the air-water (A-W) interface as suitable models for evaluating the abiotic degradation of two PHAs with different side-chain lengths and crystallinity. By controlling the polymer state (semicrystalline, amorphous), the packing density, the pH, and the degradation mechanism, we could draw several significant conclusions. (i) The maximum degree of crystallinity for a PHA film to be efficiently degraded up to pH = 12.3 is 40%. (ii) PHA made of repeating units with shorter side-chain length are more easily hydrolyzed under alkaline conditions. The efficiency of alkaline hydrolysis decreased by about 65% when the polymer was 40% crystalline. (iii) In PHA films with a relatively high initial crystallinity, abiotic degradation initiated a chemi-crystallization phenomenon, detected as an increase in the storage modulus (E'). This could translate into an increase in brittleness and reduction in the material degradability. Finally, we demonstrate the stability of the measurement system for long-term experiments, which allows degradation conditions for polymers that could closely simulate real-time degradation.
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Affiliation(s)
- Natalia A Tarazona
- Institute of Biomaterial Science and Berlin-Brandenburg Center for Regenerative Therapies , Helmholtz-Zentrum Geesthacht , Kantstrasse 55 , 14513 Teltow , Germany
| | - Rainhard Machatschek
- Institute of Biomaterial Science and Berlin-Brandenburg Center for Regenerative Therapies , Helmholtz-Zentrum Geesthacht , Kantstrasse 55 , 14513 Teltow , Germany
| | - Andreas Lendlein
- Institute of Biomaterial Science and Berlin-Brandenburg Center for Regenerative Therapies , Helmholtz-Zentrum Geesthacht , Kantstrasse 55 , 14513 Teltow , Germany.,Institute of Chemistry , University of Potsdam , Karl-Liebknecht-Strasse 24-25 , 14469 Potsdam , Germany
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Su M, Jiang Y, Yu F, Yu T, Du S, Xu Y, Yang L, Liu H. Mirrorlike Plasmonic Capsules for Online Microfluidic Raman Analysis of Drug in Human Saliva and Urine. ACS APPLIED BIO MATERIALS 2019; 2:3828-3835. [DOI: 10.1021/acsabm.9b00425] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Mengke Su
- School of Food and Biological Engineering, Engineering Research Center of Bio-Process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Yifan Jiang
- School of Food and Biological Engineering, Engineering Research Center of Bio-Process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Fanfan Yu
- School of Food and Biological Engineering, Engineering Research Center of Bio-Process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Ting Yu
- School of Food and Biological Engineering, Engineering Research Center of Bio-Process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Shanshan Du
- School of Food and Biological Engineering, Engineering Research Center of Bio-Process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Yue Xu
- School of Food and Biological Engineering, Engineering Research Center of Bio-Process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Lina Yang
- School of Food and Biological Engineering, Engineering Research Center of Bio-Process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Honglin Liu
- School of Food and Biological Engineering, Engineering Research Center of Bio-Process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, China
- Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Life Sciences, and Aptamer Engineering Center of Hunan Province, Hunan University, Changsha, Hunan 410082, China
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai 200050, China
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19
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Dynamic interfacial properties and foamability of polyelectrolyte-surfactant mixtures. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2018.11.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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20
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Fainerman VB, Kovalchuk VI, Aksenenko EV, Zinkovych II, Makievski AV, Nikolenko MV, Miller R. Dilational Viscoelasticity of Proteins Solutions in Dynamic Conditions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:6678-6686. [PMID: 29783835 DOI: 10.1021/acs.langmuir.8b00631] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Drop profile analysis tensiometry used in the oscillating drop mode provides the dilational viscoelasticity of adsorption layers at liquid interfaces. Applied during the progress of adsorption the dynamic surface rheology can be monitored. For β-casein solutions at the same surface pressure values, the larger the dynamic dilational viscoelasticity the longer the adsorption time, i.e., the smaller the studied protein concentration is. For β-lactoglobulin and human serum albumin, the differences in the viscoelasticity values are less or not dependent on the adsorption time at identical surface pressures. The observed effects are caused by the flexibility of BCS, while the globular proteins BLG and HSA do not change their conformation significantly within the adsorption layer.
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Affiliation(s)
| | | | - Eugene V Aksenenko
- Institute of Colloid Chemistry and Chemistry of Water , Kyiv (Kiev) 03680 , Ukraine
| | - Igor I Zinkovych
- Maxim Gorki Donetsk National Medical University , Kirovohrad 25015 , Ukraine
| | | | - Mykola V Nikolenko
- Ukrainian State University of Chemical Technology , Dnipro 49005 , Ukraine
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21
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Pal A, Maan R. Investigations of interactions between surface active ionic liquid 1-butyl-3-methyl imidazolium dodecylbenzenesulfonate and cationic polyelectrolyte poly(diallyldimethylammonium chloride) in aqueous solution. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.01.108] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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22
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Interfacial characteristics of binary polymer blend films spread at the air-water interface. Adv Colloid Interface Sci 2017; 247:163-171. [PMID: 28499605 DOI: 10.1016/j.cis.2017.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Indexed: 11/27/2022]
Abstract
The interfacial characteristics of binary polymer blend films spread at the air-water interface are reviewed, focusing on their surface pressures, interfacial structures, and dilational moduli as a function of the miscibility. Miscible polymer blend films show thermodynamic, structural, and dynamic properties which are a combination of those from both components in the polymer blend present at the air-water interface. No preferential adsorption is observed and the behavior does not depend on the surface concentration regime. In contrast, for immiscible polymer blend films, preferential adsorption of one polymer phase occurs at the air-water interface and the interfacial characteristics in the semi-dilute and concentrated regimes are strongly controlled by one of the components of the adsorbed polymer.
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23
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Monroy F. Surface hydrodynamics of viscoelastic fluids and soft solids: Surfing bulk rheology on capillary and Rayleigh waves. Adv Colloid Interface Sci 2017; 247:4-22. [PMID: 28735885 DOI: 10.1016/j.cis.2017.07.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 07/09/2017] [Accepted: 07/09/2017] [Indexed: 11/18/2022]
Abstract
From the recent advent of the new soft-micro technologies, the hydrodynamic theory of surface modes propagating on viscoelastic bodies has reinvigorated this field of technology with interesting predictions and new possible applications, so recovering its scientific interest very limited at birth to the academic scope. Today, a myriad of soft small objects, deformable meso- and micro-structures, and macroscopically viscoelastic bodies fabricated from colloids and polymers are already available in the materials catalogue. Thus, one can envisage a constellation of new soft objects fabricated by-design with a functional dynamics based on the mechanical interplay of the viscoelastic material with the medium through their interfaces. In this review, we recapitulate the field from its birth and theoretical foundation in the latest 1980s up today, through its flourishing in the 90s from the prediction of extraordinary Rayleigh modes in coexistence with ordinary capillary waves on the surface of viscoelastic fluids, a fact first confirmed in experiments by Dominique Langevin and me with soft gels [Monroy and Langevin, Phys. Rev. Lett. 81, 3167 (1998)]. With this observational discovery at sight, we not only settled the theory previously formulated a few years before, but mainly opened a new field of applications with soft materials where the mechanical interplay between surface and bulk motions matters. Also, new unpublished results from surface wave experiments performed with soft colloids are reported in this contribution, in which the analytic methods of wave surfing synthetized together with the concept of coexisting capillary-shear modes are claimed as an integrated tool to insightfully scrutinize the bulk rheology of soft solids and viscoelastic fluids. This dedicatory to the figure of Dominique Langevin includes an appraisal of the relevant theoretical aspects of the surface hydrodynamics of viscoelastic fluids, and the coverage of the most important experimental results obtained during the three decades of research on this field.
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Affiliation(s)
- Francisco Monroy
- Departamento de Química Física I, Facultad de Química, Universidad Complutense de Madrid, E28040 Madrid, Spain; Unit of Traslational Biophysics, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), E28041 Madrid, Spain.
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24
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Dominique Langevin Festschrift: Four decades opening gates in Colloid and Interface Science. Adv Colloid Interface Sci 2017; 247:1-3. [PMID: 28803628 DOI: 10.1016/j.cis.2017.07.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 07/24/2017] [Indexed: 11/23/2022]
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25
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Electro-optic Kerr effect in the study of mixtures of oppositely charged colloids. The case of polymer-surfactant mixtures in aqueous solutions. Adv Colloid Interface Sci 2017; 247:234-257. [PMID: 28552423 DOI: 10.1016/j.cis.2017.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/04/2017] [Accepted: 05/14/2017] [Indexed: 11/20/2022]
Abstract
In this review I highlight a very sensitive experimental technique for the study of polymer-surfactant complexation: The electro-optic Kerr effect. This review does not intend to be exhaustive in covering the Kerr Effect nor polymer-surfactant systems, instead it aims to call attention to an experimental technique that, even if applied in a qualitative manner, could give very rich and unique information about the structures and aggregation processes occurring in mixtures of oppositely charged colloids. The usefulness of electric birefringence experiments in the study of such systems is illustrated by selected results from literature in hope of stimulating the realization of more birefringence experiments on similar systems. This review is mainly aimed at, but not restricted to, researchers working in polyelectrolyte-surfactant mixtures in aqueous solutions, Kerr effect is a powerful experimental tool that could be used in the study of many systems in diverse areas of colloidal physics.
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26
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Boisselier É, Demers É, Cantin L, Salesse C. How to gather useful and valuable information from protein binding measurements using Langmuir lipid monolayers. Adv Colloid Interface Sci 2017; 243:60-76. [PMID: 28372794 DOI: 10.1016/j.cis.2017.03.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 03/14/2017] [Accepted: 03/15/2017] [Indexed: 12/22/2022]
Abstract
This review presents data on the influence of various experimental parameters on the binding of proteins onto Langmuir lipid monolayers. The users of the Langmuir methodology are often unaware of the importance of choosing appropriate experimental conditions to validate the data acquired with this method. The protein Retinitis pigmentosa 2 (RP2) has been used throughout this review to illustrate the influence of these experimental parameters on the data gathered with Langmuir monolayers. The methods detailed in this review include the determination of protein binding parameters from the measurement of adsorption isotherms, infrared spectra of the protein in solution and in monolayers, ellipsometric isotherms and fluorescence micrographs.
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Affiliation(s)
- Élodie Boisselier
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
| | - Éric Demers
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Line Cantin
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Christian Salesse
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
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27
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Huang S, Gawlitza K, von Klitzing R, Steffen W, Auernhammer GK. Structure and Rheology of Microgel Monolayers at the Water/Oil Interface. Macromolecules 2017. [DOI: 10.1021/acs.macromol.6b02779] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Shilin Huang
- Max Planck Institute
for Polymer Research, Ackermannweg
10, 55128 Mainz, Germany
| | - Kornelia Gawlitza
- Stranski-Laboratorium
für Physikalische und Theoretische Chemie, Technische Universität Berlin, Strasse des 17. Juni 124, 10623 Berlin, Germany
| | - Regine von Klitzing
- Stranski-Laboratorium
für Physikalische und Theoretische Chemie, Technische Universität Berlin, Strasse des 17. Juni 124, 10623 Berlin, Germany
| | - Werner Steffen
- Max Planck Institute
for Polymer Research, Ackermannweg
10, 55128 Mainz, Germany
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28
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Kuznetsov V, Akentiev A, Rakhimov V. Evaporation of aqueous solutions of organic acids through spread films of poly(diallyldimethylammonium chloride)/sodium dodecylsulfate complex. SEP SCI TECHNOL 2017. [DOI: 10.1080/01496395.2016.1271341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Viktor Kuznetsov
- Department of Chemistry, Saint Petersburg State University, St. Petersburg, Russian Federation
| | - Alexander Akentiev
- Department of Chemistry, Saint Petersburg State University, St. Petersburg, Russian Federation
| | - Viktor Rakhimov
- Department of Chemistry, Saint Petersburg State University, St. Petersburg, Russian Federation
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29
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Thermodynamics, interfacial pressure isotherms and dilational rheology of mixed protein-surfactant adsorption layers. Adv Colloid Interface Sci 2016. [PMID: 26198014 DOI: 10.1016/j.cis.2015.06.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proteins and their mixtures with surfactants are widely used in many applications. The knowledge of their solution bulk behavior and its impact on the properties of interfacial layers made great progress in the recent years. Different mechanisms apply to the formation process of protein/surfactant complexes for ionic and non-ionic surfactants, which are governed mainly by electrostatic and hydrophobic interactions. The surface activity of these complexes is often remarkably different from that of the individual protein and has to be considered in respective theoretical models. At very low protein concentration, small amounts of added surfactants can change the surface activity of proteins remarkably, even though no strongly interfacial active complexes are observed. Also small added amounts of non-ionic surfactants change the surface activity of proteins in the range of small bulk concentrations or surface coverages. The modeling of the equilibrium adsorption behavior of proteins and their mixtures with surfactants has reached a rather high level. These models are suitable also to describe the high frequency limits of the dilational viscoelasticity of the interfacial layers. Depending on the nature of the protein/surfactant interactions and the changes in the interfacial layer composition rather complex dilational viscoelasticities can be observed and described by the available models. The differences in the interfacial behavior, often observed in literature for studies using different experimental methods, are at least partially explained by a depletion of proteins, surfactants and their complexes in the range of low concentrations. A correction of these depletion effects typically provides good agreement between the data obtained with different methods, such as drop and bubble profile tensiometry.
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30
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Kuznetsov V, Rakhimov V, Akentiev A. Evaporation of aqueous solutions of organic acids through spread films of sodium polystyrene sulfonate/dodecyl trimethyl ammonium bromide complex. SEP SCI TECHNOL 2016. [DOI: 10.1080/01496395.2015.1083031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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31
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Mitrinova Z, Tcholakova S, Denkov N, Ananthapadmanabhan K. Role of interactions between cationic polymers and surfactants for foam properties. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2015.10.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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32
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Bureiko A, Trybala A, Kovalchuk N, Starov V. Current applications of foams formed from mixed surfactant-polymer solutions. Adv Colloid Interface Sci 2015; 222:670-7. [PMID: 25455806 DOI: 10.1016/j.cis.2014.10.001] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 09/30/2014] [Accepted: 10/01/2014] [Indexed: 02/08/2023]
Abstract
Foams cannot be generated without the use of special foaming agents, as pure liquids do not foam. The most common foaming agents are surfactants, however often for foam stability one active agent is not enough, it is necessary to add other component to increase foam lifetime. Foams on everyday use are mostly made from mixture of different components. Properly chosen combinations of two active ingredients lead to a faster foam formation and increased foam stability. During the last decade polymers (mainly polyelectrolytes and proteins) have become frequently used additives to foaming solutions. Mixtures of surfactants and polymers often demonstrate different foaming properties in comparison to surfactant only or polymer only solutions. The nature of surfactant-polymer interactions is complicated and prediction of resulting foaming properties of such formulations is not straightforward. Properties and foaming of surfactant-polymer mixtures are discussed as well as current applications of foams and foaming agents as foams are widely used in cosmetics, pharmaceutics, medicine and the food industry.
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Affiliation(s)
| | - Anna Trybala
- Department of Chemical Engineering, Loughborough University, UK
| | - Nina Kovalchuk
- Department of Chemical Engineering, Loughborough University, UK; Institute of Biocolloid Chemistry, Kiev, Ukraine
| | - Victor Starov
- Department of Chemical Engineering, Loughborough University, UK.
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33
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Deschênes L, Lyklema J, Danis C, Saint-Germain F. Phase transitions in polymer monolayers: Application of the Clapeyron equation to PEO in PPO-PEO Langmuir films. Adv Colloid Interface Sci 2015; 222:199-214. [PMID: 25488283 DOI: 10.1016/j.cis.2014.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 11/04/2014] [Accepted: 11/05/2014] [Indexed: 11/19/2022]
Abstract
In this paper we investigate the application of the two-dimensional Clapeyron law to polymer monolayers. This is a largely unexplored area of research. The main problems are (1) establishing if equilibrium is reached and (2) if so, identifying and defining phases as functions of the temperature. Once this is validated, the Clapeyron law allows us to obtain the entropy and enthalpy differences between two coexisting phases. In turn, this information can be used to obtain insight into the conformational properties of the films and changes therein. This approach has a wide potential for obtaining additional information on polymer adsorption at interfaces and the structure of their monolayer films. The 2D Clapeyron law was applied emphasizing polyethylene oxide (PEO) in polypropylene oxide (PPO)-PEO block copolymers, based on new well-defined data for their Langmuir films. Values for enthalpy per monomer of 0.12 and 0.23 kT were obtained for the phase transition of two different PEO chains (Neo of 2295 and 409, respectively). This enthalpy was estimated to correspond to 1.2±0.4 kT per EO monomer present in train conformation at the air/water interface.
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Affiliation(s)
- Louise Deschênes
- Food Research and Development Centre, 3600 Casavant Blvd West, Saint-Hyacinthe, QC J2S 8E3, Canada
| | - Johannes Lyklema
- Laboratory for Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, Netherlands
| | - Claude Danis
- Food Research and Development Centre, 3600 Casavant Blvd West, Saint-Hyacinthe, QC J2S 8E3, Canada
| | - François Saint-Germain
- Food Research and Development Centre, 3600 Casavant Blvd West, Saint-Hyacinthe, QC J2S 8E3, Canada
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34
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Viscoelasticity of chia (Salvia hispanica L.) seed mucilage dispersion in the vicinity of an oil-water interface. Food Hydrocoll 2015. [DOI: 10.1016/j.foodhyd.2015.03.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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Langmuir monolayers of non-ionic polymers: Equilibrium or metastability? Case study of PEO and its PPO–PEO diblock copolymers. J Colloid Interface Sci 2015; 449:494-505. [DOI: 10.1016/j.jcis.2015.01.072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 01/23/2015] [Accepted: 01/26/2015] [Indexed: 10/24/2022]
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36
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Gochev G. Thin liquid films stabilized by polymers and polymer/surfactant mixtures. Curr Opin Colloid Interface Sci 2015. [DOI: 10.1016/j.cocis.2015.03.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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37
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Choudhary K, Manjuladevi V, Gupta RK, Bhattacharyya P, Hazra A, Kumar S. Ultrathin films of TiO2 nanoparticles at interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:1385-1392. [PMID: 25557246 DOI: 10.1021/la503514p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The properties of a material change remarkably as a result of the scaling dimensions. The Langmuir-Blodgett (LB) film deposition technique is known to offer precise control over the film thickness and the interparticle separation. To form a well-ordered LB film, it is essential to form a stable Langmuir film at the air-water interface. Here, we report our studies on ultrathin films of TiO2 nanoparticles at air-water and air-solid interfaces. The Langmuir film of TiO2 nanoparticles at the air-water interface was found to be very stable, and it exhibits loose-packing and close-packing phases. The LB films were transferred onto solid substrates for characterization and application. The surface morphology of the LB film was obtained by a field emission scanning electron microscope. The optical and electronic properties of the LB films of TiO2 nanoparticles were studied using UV-vis spectroscopy and current-voltage measurements, respectively. The LB film of TiO2 nanoparticles was employed for ethanol gas sensing, and the sensing performance was compared to that of bulk material. Because of the enormous gain in the surface to volume ratio and the increase in crystalline defect density in the ultrathin LB film of TiO2 nanoparticles, the LB film is found to be a potential functional layer for ethanol sensing as compared to the bulk material.
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Affiliation(s)
- Keerti Choudhary
- Department of Physics, Birla Institute of Technology and Science (BITS) , Pilani, Rajasthan 333031, India
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38
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The importance of experimental design on measurement of dynamic interfacial tension and interfacial rheology in diffusion-limited surfactant systems. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2014.11.035] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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39
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Li Z, Ma X, Zang D, Guan X, Zhu L, Liu J, Chen F. Interfacial rheology and aggregation behaviour of amphiphilic CBABC-type pentablock copolymers at the air–water interface: effects of block ratio and chain length. RSC Adv 2015. [DOI: 10.1039/c5ra08109b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The interfacial rheology, aggregation behaviour and packing model of the structure evolution of three amphiphilic CBABC-type pentablock copolymers were investigated at the air–water interface.
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Affiliation(s)
- Zhiguang Li
- Key Laboratory of Space Applied Physics and Chemistry
- Ministry of Education
- School of Science
- Northwestern Polytechnical University
- Xi’an 710129
| | - Xiaoyan Ma
- Key Laboratory of Space Applied Physics and Chemistry
- Ministry of Education
- School of Science
- Northwestern Polytechnical University
- Xi’an 710129
| | - Duyang Zang
- Key Laboratory of Space Applied Physics and Chemistry
- Ministry of Education
- School of Science
- Northwestern Polytechnical University
- Xi’an 710129
| | - Xinghua Guan
- Key Laboratory of Space Applied Physics and Chemistry
- Ministry of Education
- School of Science
- Northwestern Polytechnical University
- Xi’an 710129
| | - Lin Zhu
- Key Laboratory of Space Applied Physics and Chemistry
- Ministry of Education
- School of Science
- Northwestern Polytechnical University
- Xi’an 710129
| | - Jinshu Liu
- Key Laboratory of Space Applied Physics and Chemistry
- Ministry of Education
- School of Science
- Northwestern Polytechnical University
- Xi’an 710129
| | - Fang Chen
- Key Laboratory of Space Applied Physics and Chemistry
- Ministry of Education
- School of Science
- Northwestern Polytechnical University
- Xi’an 710129
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40
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Dynamic surface elasticity of mixed poly(diallyldimethylammonium chloride)/sodium dodecyl sulfate/NaCl solutions. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2014.01.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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41
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Georgiev GA, Yokoi N, Ivanova S, Tonchev V, Nencheva Y, Krastev R. Surface relaxations as a tool to distinguish the dynamic interfacial properties of films formed by normal and diseased meibomian lipids. SOFT MATTER 2014; 10:5579-88. [PMID: 24959988 DOI: 10.1039/c4sm00758a] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The surface properties of human meibomian lipids (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The dynamic interfacial properties of films by MGS from normal eyes (nMGS) and eyes with meibomian gland dysfunction (dMGS) were studied using a Langmuir surface balance. The behavior of the samples during dynamic area changes was evaluated by surface pressure-area isotherms and isocycles. The surface dilatational rheology of the films was examined in the frequency range 10(-5) to 1 Hz by the stress-relaxation method. A significant difference was found, with dMGS showing slow viscosity-dominated relaxation at 10(-4) to 10(-3) Hz, whereas nMGS remained predominantly elastic over the whole range. A Cole-Cole plot revealed two characteristic processes contributing to the relaxation, fast (on the scale of characteristic time τ < 5 s) and slow (τ > 100 s), the latter prevailing in dMGS films. Brewster angle microscopy revealed better spreading of nMGS at the air-water interface, whereas dMGS layers were non-uniform and patchy. The distinctions in the interfacial properties of the films in vitro correlated with the accelerated degradation of meibum layer pattern at the air-tear interface and with the decreased stability of TF in vivo. These results, and also recent findings on the modest capability of meibum to suppress the evaporation of the aqueous subphase, suggest the need for a re-evaluation of the role of MGS. The probable key function of meibomian lipids might be to form viscoelastic films capable of opposing dilation of the air-tear interface. The impact of temperature on the meibum surface properties is discussed in terms of its possible effect on the normal structure of the film.
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Affiliation(s)
- Georgi As Georgiev
- Department of Biochemistry, Faculty of Biology, University of Sofia, Sofia, Bulgaria.
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Campbell RA, Yanez Arteta M, Angus-Smyth A, Nylander T, Noskov BA, Varga I. Direct impact of nonequilibrium aggregates on the structure and morphology of Pdadmac/SDS layers at the air/water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:8664-8674. [PMID: 24988363 DOI: 10.1021/la500621t] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We discuss different nonequilibrium mechanisms by which bulk aggregates directly modify, and can even control, the interfacial structure and morphology of an oppositely charged polyelectrolyte/surfactant (P/S) mixture. Samples are categorized at the air/water interface with respect to the dynamic changes in the bulk phase behavior, the bulk composition, and the sample history using complementary surface-sensitive techniques. First, we show that bulk aggregates can spontaneously interact with the adsorption layer and are retained in it and that this process occurs most readily for positively charged aggregates with an expanded structure. In this case, key nonequilibrium issues of aggregate dissociation and spreading of surface-active material at the interface have a marked influence on the macroscopic interfacial properties. In a second distinct mechanism, aggregates inherently become trapped at the interface during its creation and lateral flocculation occurs. This irreversible process is most pronounced for aggregates with the lowest charge. A third mechanism involves the deposition of aggregates at interfaces due to their transport under gravity. The specificity of this process at an interface depends on its location and is mediated by density effects in the bulk. The prevalence of each mechanism critically depends on a number of different factors, which are outlined systematically here for the first time. This study highlights the sheer complexity by which aggregates can directly impact the interfacial properties of a P/S mixture. Our findings offer scope for understanding seemingly mysterious irreproducible effects which can compromise the performance of formulations in wide-ranging applications from foams to emulsions and lubricants.
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Affiliation(s)
- Richard A Campbell
- Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
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43
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Ábrahám Á, Kardos A, Mezei A, Campbell RA, Varga I. Effects of ionic strength on the surface tension and nonequilibrium interfacial characteristics of poly(sodium styrenesulfonate)/dodecyltrimethylammonium bromide mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:4970-4979. [PMID: 24712308 DOI: 10.1021/la500637v] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We rationalize the surface tension behavior and nonequilibrium interfacial characteristics of high molecular weight poly(sodium styrenesulfonate)/dodecyltrimethylammonium bromide (NaPSS/DTAB) mixtures with respect to the ionic strength. Excellent agreement is achieved between experimental data and our recent empirical model [Langmuir 2013, 29, 11554], which is based on the lack of colloidal stability of bulk aggregates in the phase separation region and has no free fitting parameters. We show that the size of a surface tension peak positioned at the edge of the phase separation region can be suppressed by the addition of inert electrolyte, which lowers the critical micelle concentration in relation to the phase separation region. Such manipulation of the peak is possible for the 100 ppm NaPSS/DTAB system because there is a high free surfactant concentration in the phase separation region. The close agreement of our model with the experimental data of samples in the phase separation region with respect to the ionic strength indicates that the surface tension behavior can be rationalized in terms of comprehensive precipitation regardless of whether there is a peak or not. The time scale of precipitation for the investigated system is on the order of one month, which emphasizes the need to understand the dynamic changes in the state of bulk aggregation in order to rationalize the surface properties of strongly interacting mixtures; steady state surface properties measured in the interim period will represent samples far from equilibrium. We show also that the surface properties of samples of low ionic strength outside the equilibrium phase separation region can be extreme opposites depending on the sample history, which is attributed to the generation of trapped nonequilibrium states. This work highlights the need to validate the underlying nature of oppositely charged polyelectrolyte/surfactant systems prior to the interpretation of experimental data within an equilibrium framework.
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Affiliation(s)
- Ágnes Ábrahám
- Institute of Chemistry, Eötvös Loránd University , Budapest 112, P.O. Box 32, H-1518 Hungary
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Lhor M, Bernier SC, Horchani H, Bussières S, Cantin L, Desbat B, Salesse C. Comparison between the behavior of different hydrophobic peptides allowing membrane anchoring of proteins. Adv Colloid Interface Sci 2014; 207:223-39. [PMID: 24560216 PMCID: PMC4028306 DOI: 10.1016/j.cis.2014.01.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 01/11/2014] [Accepted: 01/13/2014] [Indexed: 10/25/2022]
Abstract
Membrane binding of proteins such as short chain dehydrogenase reductases or tail-anchored proteins relies on their N- and/or C-terminal hydrophobic transmembrane segment. In this review, we propose guidelines to characterize such hydrophobic peptide segments using spectroscopic and biophysical measurements. The secondary structure content of the C-terminal peptides of retinol dehydrogenase 8, RGS9-1 anchor protein, lecithin retinol acyl transferase, and of the N-terminal peptide of retinol dehydrogenase 11 has been deduced by prediction tools from their primary sequence as well as by using infrared or circular dichroism analyses. Depending on the solvent and the solubilization method, significant structural differences were observed, often involving α-helices. The helical structure of these peptides was found to be consistent with their presumed membrane binding. Langmuir monolayers have been used as membrane models to study lipid-peptide interactions. The values of maximum insertion pressure obtained for all peptides using a monolayer of 1,2-dioleoyl-sn-glycero-3-phospho-ethanolamine (DOPE) are larger than the estimated lateral pressure of membranes, thus suggesting that they bind membranes. Polarization modulation infrared reflection absorption spectroscopy has been used to determine the structure and orientation of these peptides in the absence and in the presence of a DOPE monolayer. This lipid induced an increase or a decrease in the organization of the peptide secondary structure. Further measurements are necessary using other lipids to better understand the membrane interactions of these peptides.
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Affiliation(s)
- Mustapha Lhor
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Sarah C Bernier
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Habib Horchani
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Sylvain Bussières
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Line Cantin
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Bernard Desbat
- CBMN-UMR 5248 CNRS, Université de Bordeaux, IPB, Allée Geoffroy Saint Hilaire, 33600 Pessac, France
| | - Christian Salesse
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada.
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Carrillo-Navas H, Vernon-Carter E, Alvarez-Ramírez J. Viscoelastic retardation spectra of interfaces formed by water/glycerol monostearate crystals in canola oil dispersions. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2013.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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46
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Petkova R, Tcholakova S, Denkov N. Role of polymer–surfactant interactions in foams: Effects of pH and surfactant head group for cationic polyvinylamine and anionic surfactants. Colloids Surf A Physicochem Eng Asp 2013. [DOI: 10.1016/j.colsurfa.2013.01.021] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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47
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Li D, Wagner NJ. Universal binding behavior for ionic alkyl surfactants with oppositely charged polyelectrolytes. J Am Chem Soc 2013; 135:17547-55. [PMID: 24160889 DOI: 10.1021/ja408587u] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Oppositely charged polyelectrolyte-surfactant mixtures are ubiquitous in biology and the basis of numerous consumer healthcare products. Despite their broad use, however, a rational approach to their formulation remains challenging because of the complicated association mechanisms. Through compilation and analysis of literature reports and our own research, we have developed a semiempirical correlation of the binding strength of surfactants to polyelectrolytes in salt-free mixtures as a function of the polyion linear charge density and the surfactant hydrophobicity. We have found that the cooperative binding strength increases as the square of the polyelectrolyte's linear charge density and in proportion to the surfactant's hydrophobicity, such that a quantitative relationship holds across a broad range of polyelectrolytes. Deviations from the correlation reveal the role of system-specific interactions not considered in the analysis. This engineering relationship aids in the rational design of oppositely charged polyelectrolyte-surfactant formulations for consumer products and biomedicines by enabling the prediction of binding strengths in polyelectrolyte-surfactant mixtures based on mesoscale parameters determined from the chemical composition.
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Affiliation(s)
- Dongcui Li
- Center for Neutron Science, Center for Molecular and Engineering Thermodynamics, Department of Chemical & Biomolecular Engineering, University of Delaware , Newark, Delaware 19716, United States
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48
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Micheau C, Bauduin P, Diat O, Faure S. Specific salt and pH effects on foam film of a pH sensitive surfactant. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:8472-8481. [PMID: 23758636 DOI: 10.1021/la400879t] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Steady state foams made of a pH sensitive surfactant, nonaoxyethylene oleylether carboxylic acid, with ion complexing properties was studied using small angle neutron scattering (SANS). The effect of pH variation and salt addition on the foam film thickness was investigated and discussed in terms of the influent parameters stabilizing the foam such as surface properties and electrostatic effects determined by tensiometry and zeta potential measurements. The decrease in the film thickness by adding mono (Na(+)) and divalent (Ca(2+)) salts is classically explained by screening of the double layer in foam films (transverse interactions). On the contrary, addition of acid or complexing ion (Nd(3+)) results in an increase in the film thickness and can be analyzed in terms of cohesive forces between surfactants at the liquid/gas interface (lateral interactions). pH and specific salt effects revealed that foams produced by nonaoxyethylene oleylether carboxylic acid are of interest in the potential use of this surfactant in ion separation process.
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Affiliation(s)
- Cyril Micheau
- Institut de Chimie Séparative de Marcoule (ICSM), UMR 5257 (CEA/CNRS/UM2/ENSCM) BP 17171-30207, Bagnols Sur Cèze Cedex, France
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49
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López-Montero I, Catapano ER, Espinosa G, Arriaga LR, Langevin D, Monroy F. Shear and compression rheology of Langmuir monolayers of natural ceramides: solid character and plasticity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:6634-6644. [PMID: 23621106 DOI: 10.1021/la400448x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The present work addresses the fundamental question of membrane elasticity of ceramide layers with a special focus on the plastic regime. The compression and shear viscoelasticity of egg-ceramide Langmuir monolayers were investigated using oscillatory surface rheology in the linear regime and beyond. High compression and shear moduli were measured at room temperature-a clear signature for a solid behavior. At deformations larger than one per mill, egg-ceramide monolayers display plastic features characterized by a decrease of the storage modulus followed by a viscous regime typical of fluid lipids. This behavior is accompanied by a marked decrease of the loss modulus with increasing stress above a yield point. The results permit to univocally classify ceramide monolayers as 2D solids able to undergo plastic deformations, at the difference of typical fluid lipid monolayers. These unusual features are likely to have consequences in the mechanical behavior of ceramide-rich emplacements in biological membranes.
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Affiliation(s)
- Iván López-Montero
- Departamento de Química Física I, Universidad Complutense, 28040 Madrid, Spain
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50
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Direct deposition of chitosan macromolecules on a substrate from solutions in supercritical carbon dioxide: Solubility and conformational analysis. Eur Polym J 2012. [DOI: 10.1016/j.eurpolymj.2012.03.003] [Citation(s) in RCA: 10] [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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