1
|
Maine A, Encinas MV, Pavez J, Urzúa M, Günther G, Reyes I, Briones X. On the Preparation of Thin Films of Stearyl Methacrylate Directly Photo-polymerized at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11658-11665. [PMID: 36112511 DOI: 10.1021/acs.langmuir.2c01513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Characterization of bidimensional polymeric films at the air-water interface in the Langmuir trough, despite being a recurrent topic, usually refers to films of already formed polymeric materials, with very scarce reports on direct polymerization at the air-water interface. In the present work, we studied the photo-polymerization of stearyl methacrylate directly at the air-water interface under a nitrogen atmosphere, with the radical initiator solubilized in the aqueous phase. Two-dimensional (2D) polymerization was monitored by measuring the pressure-area isotherm at different irradiation times. The polymerization leads to a film with an isotherm different from that observed for the monomer, where the surface pressure is directly related to the irradiation time. The shape of this isotherm confirms the presence of a compressed liquid phase, where a higher order can be attained as a consequence of stronger packing forces involving polymer chains. The presence of inter-chain interactions allows rearrangements on the surface of the subphase, and even before the collapse a dense 2D ordering (with a solid phase-like behavior) can be observed. We present a new one-step, solvent-free procedure to obtain a photo-polymeric film directly at the air-water interface, which can be transferred to a solid surface by the Langmuir-Blodgett method, allowing film preparation of controlled thickness. Films were characterized by measuring properties such as thickness, roughness, and hydrophobicity and comparing them with films obtained from a conventional polymer. We report the differences between the interfacial behavior of amphiphilic molecules and nanomaterials such as films obtained by photo-polymerization, PSMA, directly on the air-water interface.
Collapse
Affiliation(s)
- A Maine
- Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Dr. Carlos Lorca Tobar 964, Independencia, Región Metropolitana, Casilla 233, Santiago, Chile
- Departamento de Química, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago, Chile
| | - M V Encinas
- Facultad de Química y Biología, Universidad de Santiago de Chile, Av. B. O'Higgins 3363 Santiago, Chile
| | - J Pavez
- Departamento de Química de los Materiales, Facultad de Química y Biología, Soft Matter Research-Technology Center, SMAT-C, Universidad de Santiago de Chile, Av. B. O'Higgins 3363 Santiago, Chile
| | - M Urzúa
- Departamento de Química, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago, Chile
| | - G Günther
- Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Dr. Carlos Lorca Tobar 964, Independencia, Región Metropolitana, Casilla 233, Santiago, Chile
| | - I Reyes
- Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Dr. Carlos Lorca Tobar 964, Independencia, Región Metropolitana, Casilla 233, Santiago, Chile
- Departamento de Química, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago, Chile
| | - X Briones
- Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Dr. Carlos Lorca Tobar 964, Independencia, Región Metropolitana, Casilla 233, Santiago, Chile
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Fundamental insights in PLGA degradation from thin film studies. J Control Release 2019; 319:276-284. [PMID: 31884098 DOI: 10.1016/j.jconrel.2019.12.044] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/20/2019] [Accepted: 12/26/2019] [Indexed: 01/18/2023]
Abstract
Poly(lactide-co-glycolide)s are commercially available degradable implant materials, which are typically selected based on specifications given by the manufacturer, one of which is their molecular weight. Here, we address the question whether variations in the chain length and their distribution affect the degradation behavior of Poly[(rac-lactide)-co-glycolide]s (PDLLGA). The hydrolysis was studied in ultrathin films at the air-water interface in order to rule out any morphological effects. We found that both for purely hydrolytic degradation as well as under enzymatic catalysis, the molecular weight has very little effect on the overall degradation kinetics of PDLLGAs. The quantitative analysis suggested a random scission mechanism. The monolayer experiments showed that an acidic micro-pH does not accelerate the degradation of PDLLGAs, in contrast to alkaline conditions. The degradation experiments were combined with interfacial rheology measurements, which showed a drastic decrease of the viscosity at little mass loss. The extrapolated molecular weight behaved similar to the viscosity, dropping to a value near to the solubility limit of PDLLGA oligomers before mass loss set in. This observation suggests a solubility controlled degradation of PDLLGA. Conclusively, the molecular weight affects the degradation of PDLLGA devices mostly in indirect ways, e.g. by determining their morphology and porosity during fabrication. Our study demonstrates the relevance of the presented Langmuir degradation method for the design of controlled release systems.
Collapse
|
4
|
Aggregation behavior of star-shaped fluoropolymers containing polyhedral oligomeric silsesquioxane (POSS) at the air–water interface. Colloid Polym Sci 2016. [DOI: 10.1007/s00396-016-3986-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
5
|
Simon S, Subramanian S, Gao B, Sjöblom J. Interfacial Shear Rheology of Gels Formed at the Oil/Water Interface by Tetrameric Acid and Calcium Ion: Influence of Tetrameric Acid Structure and Oil Composition. Ind Eng Chem Res 2015. [DOI: 10.1021/acs.iecr.5b02165] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sébastien Simon
- Ugelstad
Laboratory, Department
of Chemical Engineering, the Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Sreedhar Subramanian
- Ugelstad
Laboratory, Department
of Chemical Engineering, the Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Bicheng Gao
- Ugelstad
Laboratory, Department
of Chemical Engineering, the Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Johan Sjöblom
- Ugelstad
Laboratory, Department
of Chemical Engineering, the Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| |
Collapse
|
6
|
Deshmukh OS, van den Ende D, Stuart MC, Mugele F, Duits MHG. Hard and soft colloids at fluid interfaces: Adsorption, interactions, assembly & rheology. Adv Colloid Interface Sci 2015; 222:215-27. [PMID: 25288385 DOI: 10.1016/j.cis.2014.09.003] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 09/09/2014] [Accepted: 09/13/2014] [Indexed: 11/15/2022]
Abstract
Soft microgel particles inherently possess qualities of both polymers as well as particles. We review the similarities and differences between soft microgel particles and stiff colloids at fluid-fluid interfaces. We compare two fundamental aspects of particle-laden interfaces namely the adsorption kinetics and the interactions between adsorbed particles. Although it is well established that the transport of both hard particles and microgels to the interface is driven by diffusion, the analysis of the adsorption kinetics needs reconsideration and a proper equation of state relating the surface pressure to the adsorbed mass should be used. We review the theoretical and experimental investigations into the interactions of particles at the interface. The rheology of the interfacial layers is intimately related to the interactions, and the differences between hard particles and microgels become pronounced. The assembly of particles into the layer is another distinguishing factor that separates hard particles from soft microgel particles. Microgels deform substantially upon adsorption and the stability of a microgel-stabilized emulsion depends on the conformational changes triggered by external stimuli.
Collapse
Affiliation(s)
- Omkar S Deshmukh
- Physics of Complex Fluids Group, Dept. Science and Technology, University of Twente, Enschede, The Netherlands
| | - Dirk van den Ende
- Physics of Complex Fluids Group, Dept. Science and Technology, University of Twente, Enschede, The Netherlands
| | - Martien Cohen Stuart
- Physics of Complex Fluids Group, Dept. Science and Technology, University of Twente, Enschede, The Netherlands; Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Wageningen, The Netherlands
| | - Frieder Mugele
- Physics of Complex Fluids Group, Dept. Science and Technology, University of Twente, Enschede, The Netherlands
| | - Michel H G Duits
- Physics of Complex Fluids Group, Dept. Science and Technology, University of Twente, Enschede, The Netherlands.
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Karbaschi M, Lotfi M, Krägel J, Javadi A, Bastani D, Miller R. Rheology of interfacial layers. Curr Opin Colloid Interface Sci 2014. [DOI: 10.1016/j.cocis.2014.08.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
|
10
|
Langevin D. Surface shear rheology of monolayers at the surface of water. Adv Colloid Interface Sci 2014; 207:121-30. [PMID: 24321860 DOI: 10.1016/j.cis.2013.10.030] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 10/25/2013] [Accepted: 10/29/2013] [Indexed: 11/18/2022]
Abstract
The knowledge of surface shear rheology is important to understand and model flow in systems where interfaces are present: multiphase flow, wetting, foaming and others. The topic has been investigated for more than 100 years, but the knowledge accumulated is still partial. The experimental devices used for the measurement of the viscoelastic parameters are delicate to operate and the response of the monolayers is complex, usually non-linear and time dependent. Furthermore, it is difficult to decouple from the response of the bulk liquid. Important discrepancies between microscopic and macroscopic methods were reported and remain to be clarified. The knowledge of shear properties does not suffice in general to achieve proper descriptions of the flow behavior and measurements of compression properties are needed as well. This paper presents examples taken from the literature and discusses the current level of understanding.
Collapse
Affiliation(s)
- D Langevin
- Laboratoire de Physique des Solides, Université Paris Sud 11, Bâtiment 510, 91405 Orsay, France
| |
Collapse
|
11
|
Behavior of polymer chains grafted from latex particles at soft interfaces. Colloid Polym Sci 2014. [DOI: 10.1007/s00396-013-3097-4] [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]
|
12
|
The chemistry of tetrameric acids in petroleum. Adv Colloid Interface Sci 2014; 205:319-38. [PMID: 24439257 DOI: 10.1016/j.cis.2013.12.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Revised: 12/16/2013] [Accepted: 12/18/2013] [Indexed: 11/21/2022]
Abstract
This article reviews the properties of a novel class of molecules: the tetrameric acids. These molecules have brought a large interest in petroleum science since the discovery of the family of molecules named ARN in 2004. ARN, which is naturally present in oil, is responsible, by reaction with calcium ion, of the formation of calcium naphthenate deposits; organic deposits that cause irregularities in crude oil production and processing. In order to study the properties of ARN, a model tetrameric acid molecule mimicking some of its properties named BP-10 has been developed in 2008 by Nordgård and Sjöblom and has been extensively used since then. After presenting the experimental techniques used to study the tetrameric acids, this review describes in detail the structure, preparation, detection and the bulk and interfacial properties of tetrameric acids ARN and BP-10. Finally the prediction of the operational problems with calcium naphthenate precipitation in new fields is discussed.
Collapse
|
13
|
Monroy F, Arriaga LR, Langevin D. Langmuir polymer films: recent results and new perspectives. Phys Chem Chem Phys 2012; 14:14450-9. [DOI: 10.1039/c2cp42454a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
14
|
Study of the monolayer structure and wettability properties of silica nanoparticles and CTAB using the Langmuir trough technique. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2010.11.042] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
15
|
Maestro A, Guzmán E, Chuliá R, Ortega F, Rubio RG, Miller R. Fluid to soft-glass transition in a quasi-2D system: thermodynamic and rheological evidences for a Langmuir monolayer. Phys Chem Chem Phys 2011; 13:9534-9. [PMID: 21483985 DOI: 10.1039/c1cp20305c] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report an experimental study that points out the existence of a fluid to soft-glass transition in Langmuir polymer monolayers of poly(methyl methacrylate) (PMMA), for which the water/air interface behaves as a poor-solvent. The temperature dependence of surface pressure vs. surface area equilibrium isotherms shows a glass-like transition temperature at T(g,2D)≈ 298 K, significantly lower than the value for bulk PMMA (T(g,bulk)≈ 378 K). The plot of the film thickness h vs. temperature shows a sharp change of slope at about the same temperature, 298 K, which is a typical hallmark of a glass transition in thin polymer films [J. L. Keddie, R. A. L. Jones, R. A. Cory, Europhys. Lett., 1996, 27, 59-64]. Furthermore, slightly above T(g,2D), the temperature dependence of the dilational viscosity does not follow an Arrhenius law, but instead can be described by a Vogel-Fulcher-Tamman equation with parameters that are typical of a fragile glass. Not only the qualitative behavior of three distinct equilibrium and dynamic properties, but also the quantitative agreement of the values of T(g) obtained, are a strong evidence of the existence of a fluid to soft-glass transition in this quasi-2D system.
Collapse
Affiliation(s)
- Armando Maestro
- Departamento de Química Física I, Facultad de Química, Universidad Complutense, 28040-Madrid, Spain.
| | | | | | | | | | | |
Collapse
|
16
|
Maestro A, Ortega F, Rubio RG, Rubio MA, Krägel J, Miller R. Rheology of poly(methyl methacrylate) Langmuir monolayers: Percolation transition to a soft glasslike system. J Chem Phys 2011; 134:104704. [DOI: 10.1063/1.3560612] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
17
|
Morais JM, Rocha-Filho PA, Burgess DJ. Relationship between rheological properties and one-step W/O/W multiple emulsion formation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:17874-17881. [PMID: 21033721 DOI: 10.1021/la103358n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Formation of a normal (not temporary) W/O/W multiple emulsion via the one-step method as a result of the simultaneous occurrence of catastrophic and transitional phase inversion processes has been recently reported. Critical features of this process include the emulsification temperature (corresponding to the ultralow surface tension point), the use of a specific nonionic surfactant blend and the surfactant blend/oil phase ratio, and the addition of the surfactant blend to the oil phase. The purpose of this study was to investigate physicochemical properties in an effort to gain a mechanistic understanding of the formation of these emulsions. Bulk, surface, and interfacial rheological properties of adsorbed nonionic surfactant (CremophorRH40 and Span80) films were investigated under conditions known to affect W/O/W emulsion formation. Bulk viscosity results demonstrated that CremophorRH40 has a higher mobility in oil compared than in water, explaining the significance of the solvent phase. In addition, the bulk viscosity profile of aqueous solutions containing CremophorRH40 indicated a phase transition at around 78 ± 2 °C, which is in agreement with cubic phase formation in the Winsor III region. The similarity in the interfacial elasticity values of CremophorRH40 and Span80 indicated that canola oil has a major effect on surface activity, showing the significance of vegetable oil. The highest interfacial shear elasticity and viscosity were observed when both surfactants were added to the oil phase, indicating the importance of the microstructural arrangement. CremophorRH40/Span80 complexes tended to desorb from the solution/solution interface with increasing temperature, indicating surfactant phase formation as is theoretically predicted in the Winsor III region. Together these interfacial and bulk rheology data demonstrate that one-step W/O/W emulsions form as a result of the simultaneous occurrence of phase-transition processes in the Winsor III region and explain the critical formulation and processing parameters necessary to achieve the formation of these normal W/O/W emulsions.
Collapse
Affiliation(s)
- Jacqueline M Morais
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, Storrs, Connecticut 06269, United States
| | | | | |
Collapse
|
18
|
Ortega F, Ritacco H, Rubio RG. Interfacial microrheology: Particle tracking and related techniques. Curr Opin Colloid Interface Sci 2010. [DOI: 10.1016/j.cocis.2010.03.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
19
|
|
20
|
Langevin D, Monroy F. Interfacial rheology of polyelectrolytes and polymer monolayers at the air–water interface. Curr Opin Colloid Interface Sci 2010. [DOI: 10.1016/j.cocis.2010.02.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
21
|
Bernardini C, Stoyanov SD, Stuart MAC, Arnaudov LN, Leermakers FAM. Polymers at the water/air interface, surface pressure isotherms, and molecularly detailed modeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:11850-11861. [PMID: 20572654 DOI: 10.1021/la101003c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Surface pressure isotherms at the air/water interface are reproduced for four different polymers, poly-L-lactic acid (PLLA), poly(dimethylsiloxane) (PDMS), poly(methyl methacrylate) (PMMA), and poly(isobutylene) (PiB). The polymers have the common property that they do not dissolve in water. The four isotherms differ strongly. To unravel the underlying details that are causing these differences, we have performed molecularly detailed self-consistent field (SCF) modeling. We describe the polymers on a united atom level, taking the side groups on the monomer level into account. In line with experiments, we find that PiB spreads in a monolayer which smoothly thickens already at a very low surface pressure. PMMA has an autophobic behavior: a PMMA liquid does not spread on top of the monolayer of PMMA at the air/water interface. A thicker PMMA layer only forms after the collapse of the film at a relatively high pressure. The isotherm of PDMS has regions with extreme compressibility which are linked to a layering transition. PLLA wets the water surface and spreads homogeneously at larger areas per monomer. The classical SCF approach features only short-range nearest-neighbor interactions. For the correct positioning of the layering and for the thickening of the polymer films, we account for a power-law van der Waals contribution in the model. Two-gradient SCF computations are performed to model the interface between two coexistent PDMS films at the layering transition, and an estimation of the length of their interfacial contact is obtained, together with the associated line tension value.
Collapse
Affiliation(s)
- C Bernardini
- Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands
| | | | | | | | | |
Collapse
|
22
|
|
23
|
Maestro A, Langevin D, Monroy F. Amorphous freezing in two dimensions: from soft coils to rigid particles. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2010; 31:89-94. [PMID: 20101518 DOI: 10.1140/epje/i2010-10554-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 11/17/2009] [Accepted: 12/10/2009] [Indexed: 05/28/2023]
Abstract
The topic of the gel transition in two dimensions is revisited by considering data on the shear elasticity of Langmuir monolayers of different spherical objects. Amorphous freezing can be associated to structural percolation in a lattice able to resist shear stresses. The shear modulus and its dependence on the packing fraction are found to strongly depend on the details of the interaction potential and largely differ from expectations for entropic networks. This behaviour can be interpreted in terms of more elaborated percolation theories including central forces and bond-bending forces.
Collapse
Affiliation(s)
- A Maestro
- Departamento de Química Física I, Universidad Complutense, Madrid, Spain
| | | | | |
Collapse
|