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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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2
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Microstructure evolution and partial coalescence in the whipping process of oleofoams stabilized by monoglycerides. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2020.106245] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Hunter SJ, Armes SP. Pickering Emulsifiers Based on Block Copolymer Nanoparticles Prepared by Polymerization-Induced Self-Assembly. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15463-15484. [PMID: 33325720 PMCID: PMC7884006 DOI: 10.1021/acs.langmuir.0c02595] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/27/2020] [Indexed: 05/28/2023]
Abstract
Block copolymer nanoparticles prepared via polymerization-induced self-assembly (PISA) represent an emerging class of organic Pickering emulsifiers. Such nanoparticles are readily prepared by chain-extending a soluble homopolymer precursor using a carefully selected second monomer that forms an insoluble block in the chosen solvent. As the second block grows, it undergoes phase separation that drives in situ self-assembly to form sterically stabilized nanoparticles. Conducting such PISA syntheses in aqueous solution leads to hydrophilic nanoparticles that enable the formation of oil-in-water emulsions. Alternatively, hydrophobic nanoparticles can be prepared in non-polar media (e.g., n-alkanes), which enables water-in-oil emulsions to be produced. In this review, the specific advantages of using PISA to prepare such bespoke Pickering emulsifiers are highlighted, which include fine control over particle size, copolymer morphology, and surface wettability. This has enabled various fundamental scientific questions regarding Pickering emulsions to be addressed. Moreover, block copolymer nanoparticles can be used to prepare Pickering emulsions over various length scales, with mean droplet diameters ranging from millimeters to less than 200 nm.
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Affiliation(s)
- Saul J. Hunter
- Department of Chemistry,
Dainton Building, University of Sheffield, Brook Hill, Sheffield, South Yorkshire S3 7HF, U.K.
| | - Steven P. Armes
- Department of Chemistry,
Dainton Building, University of Sheffield, Brook Hill, Sheffield, South Yorkshire S3 7HF, U.K.
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Dieng SM, Omran Z, Anton N, Thioune O, Djiboune AR, Sy PM, Messaddeq N, Ennahar S, Diarra M, Vandamme T. Pickering nano-emulsions stabilized by Eudragit RL100 nanoparticles as oral drug delivery system for poorly soluble drugs. Colloids Surf B Biointerfaces 2020; 191:111010. [PMID: 32315927 DOI: 10.1016/j.colsurfb.2020.111010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 03/23/2020] [Accepted: 04/01/2020] [Indexed: 11/27/2022]
Abstract
The purpose of this study was to develop Pickering water-in-oil nano-emulsions only stabilized by Eudragit RL100 nanoparticles (NPs), in order to increase the nano-emulsion stability and create a barrier to improve the drug encapsulation and better control the drug release. The first part of this study was dedicated to investigating the nano-emulsion formulation by ultrasonication and understanding the interfacial behavior and role of NPs in the stabilization of the water/oil interface. The focus was on the surface coverage in the function of the formulation parameters (volume fractions) to disclose the extents and limitations of the process. The main physicochemical analysis of the Pickering nano-emulsions was performed by dynamic light scattering and transmission electron microscopy. On the other hand, the second experimental approach was dedicated to understanding the interfacial behavior of the Eudragit RL100 NPs toward a model water/oil interface, using a dynamic tensiometer with axisymmetric drop shape analysis. The study investigated the NPs' adsorption, as well as their rheological behavior. The aim of this part was to reveal the main phenomena that govern the interactions between NPs and the interface in order to understand the origin of Pickering nano-emulsions' stability. The last part of the study was concerned with the stability and in vitro release of a model encapsulated drug (ketoprofen) in a gastric and simulated intestinal environment. The results showed that Pickering nano-emulsions significantly improved the resistance to gastric pH, inducing a significantly slower drug release compared to classical nano-emulsions' stabilized surfactants. These Pickering nano-emulsions appear as a promising technology to modify the delivery of a therapeutic agent, in the function of the pH, and can be, for instance, applied to the oral drug delivery of poorly soluble drugs.
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Affiliation(s)
- Sidy Mouhamed Dieng
- Université de Strasbourg, CNRS, CAMB UMR 7199, F-67000 Strasbourg, France; Université cheikh Anta Diop de Dakar, laboratoire de pharmacie galénique, Faculté de Médecine, de Pharmacie, laboratoire de physique et biophysique pharmaceutique, Faculté de Médecine, de Pharmacie et d'Odontologie, BP : 5005, Dakar Fann, Senegal; Université de Thiès, laboratoire de pharmacie galénique, UFR santé de Thiès, Thies, Sénégal Cité Malick SY BP 967, Thiès, Senegal.
| | - Ziad Omran
- Department of Pharmaceutical Chemistry, College of Pharmacy, Umm AlQura University, 21955 Makkah, Saudi Arabia.
| | - Nicolas Anton
- Université de Strasbourg, CNRS, CAMB UMR 7199, F-67000 Strasbourg, France
| | - Oumar Thioune
- Université cheikh Anta Diop de Dakar, laboratoire de pharmacie galénique, Faculté de Médecine, de Pharmacie, laboratoire de physique et biophysique pharmaceutique, Faculté de Médecine, de Pharmacie et d'Odontologie, BP : 5005, Dakar Fann, Senegal
| | - Alphonse Rodrigue Djiboune
- Université cheikh Anta Diop de Dakar, laboratoire de pharmacie galénique, Faculté de Médecine, de Pharmacie, laboratoire de physique et biophysique pharmaceutique, Faculté de Médecine, de Pharmacie et d'Odontologie, BP : 5005, Dakar Fann, Senegal
| | - Papa Mady Sy
- Université cheikh Anta Diop de Dakar, laboratoire de pharmacie galénique, Faculté de Médecine, de Pharmacie, laboratoire de physique et biophysique pharmaceutique, Faculté de Médecine, de Pharmacie et d'Odontologie, BP : 5005, Dakar Fann, Senegal
| | - Nadia Messaddeq
- Université de Strasbourg, IGBMC, Inserm U1258, CNRS UMR7104, F-67000 Strasbourg, France
| | - Said Ennahar
- Université de Strasbourg, IPHC, UMR 7178, IPHC-DSA, CNRS, F-67400 Illkirch-Graffenstaden, France
| | - Mounibé Diarra
- Université cheikh Anta Diop de Dakar, laboratoire de pharmacie galénique, Faculté de Médecine, de Pharmacie, laboratoire de physique et biophysique pharmaceutique, Faculté de Médecine, de Pharmacie et d'Odontologie, BP : 5005, Dakar Fann, Senegal
| | - Thierry Vandamme
- Université de Strasbourg, CNRS, CAMB UMR 7199, F-67000 Strasbourg, France.
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Dieng SM, Anton N, Bouriat P, Thioune O, Sy PM, Massaddeq N, Enharrar S, Diarra M, Vandamme T. Pickering nano-emulsions stabilized by solid lipid nanoparticles as a temperature sensitive drug delivery system. SOFT MATTER 2019; 15:8164-8174. [PMID: 31593197 DOI: 10.1039/c9sm01283d] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The development of biomaterials with low environmental impact has seen increased interest in recent years. In this field, lipid nanoparticles have found a privileged place in research and industry. The purpose of this study was to develop Pickering O/W nano-emulsions only stabilized by solid lipid nanoparticles (SLNs), as a new generation of safe, non-toxic, biocompatible, and temperature-sensitive lipid nano-carriers. The first part is dedicated to understanding the interfacial behavior of SLNs and their related stabilization mechanisms onto nano-emulsions formulated by ultrasonication. Investigations were focused on the surface coverage as a function of the SLN size and volume fraction of dispersed oil, in order to prove that the droplet stabilization is effectively performed by the nanoparticles, and to disclose the limitations of this formulation. Characterization is performed by dynamic light scattering and transmission electron microscopy. The second part of the study investigated SLN adsorption on a model oil/water interface (surface tension and rheology) through an axisymmetrical drop shape analysis (drop tensiometer), following the interfacial tension and the rheological behavior. The objective of this part is to characterize the phenomenon governing the droplet/interface interactions, and disclose the rheological behavior of the interfacial SLN monolayer. The effect of temperature was also investigated, proving a real destabilization of the nano-suspension when the sample is heated above a temperature threshold, impacting on the integrity of the SLNs, which partially melt, and strongly enhancing the release of a model drug (ketoprofen) encapsulated in the nano-emulsion oil core. To conclude, Pickering nano-emulsions only stabilized by SLNs appear to be a very efficient innovative drug nano-carrier, opening new doors as a potential temperature-sensitive drug delivery system.
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Affiliation(s)
- Sidy Mouhamed Dieng
- Université de Strasbourg, CNRS, CAMB UMR 7199, F-67000 Strasbourg, France. and Université Cheikh Anta Diop de Dakar, Laboratoire de Pharmacie Galénique, Laboratoire de Physique et Biophysique Pharmaceutique, Faculté de Médecine, de Pharmacie et d'Odontologie Faculté de Médecine, de Pharmacie et d'Odontologie, BP: 5005, Dakar Fann, Senegal and Université de Thiès, Laboratoire de Pharmacie Galénique, UFR santé de Thiès, Cité Malick SY BP 967 Thiès, Thies, Senegal
| | - Nicolas Anton
- Université de Strasbourg, CNRS, CAMB UMR 7199, F-67000 Strasbourg, France.
| | - Patrick Bouriat
- University of Pau & Pays Adour, CNRS, TOTAL - UMR 5150 - LFC-R - Laboratoire des Fluides Complexes et leurs Réservoirs, BP 1155, Pau, F-64013, France
| | - Oumar Thioune
- Université Cheikh Anta Diop de Dakar, Laboratoire de Pharmacie Galénique, Laboratoire de Physique et Biophysique Pharmaceutique, Faculté de Médecine, de Pharmacie et d'Odontologie Faculté de Médecine, de Pharmacie et d'Odontologie, BP: 5005, Dakar Fann, Senegal
| | - Papa Mady Sy
- Université Cheikh Anta Diop de Dakar, Laboratoire de Pharmacie Galénique, Laboratoire de Physique et Biophysique Pharmaceutique, Faculté de Médecine, de Pharmacie et d'Odontologie Faculté de Médecine, de Pharmacie et d'Odontologie, BP: 5005, Dakar Fann, Senegal
| | - Nadia Massaddeq
- Université de Strasbourg, IGBMC, Inserm U964, CNRS UMR7104, F-67000 Strasbourg, France
| | - Said Enharrar
- Université de Strasbourg, IPHC, UMR 7178, IPHC-DSA, CNRS, Illkirch-Graffenstaden 67400, France
| | - Mounibé Diarra
- Université Cheikh Anta Diop de Dakar, Laboratoire de Pharmacie Galénique, Laboratoire de Physique et Biophysique Pharmaceutique, Faculté de Médecine, de Pharmacie et d'Odontologie Faculté de Médecine, de Pharmacie et d'Odontologie, BP: 5005, Dakar Fann, Senegal
| | - Thierry Vandamme
- Université de Strasbourg, CNRS, CAMB UMR 7199, F-67000 Strasbourg, France.
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Yu K, Zhang H, Biggs S, Xu Z, Cayre OJ, Harbottle D. The rheology of polyvinylpyrrolidone-coated silica nanoparticles positioned at an air-aqueous interface. J Colloid Interface Sci 2018; 527:346-355. [DOI: 10.1016/j.jcis.2018.05.035] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 05/09/2018] [Accepted: 05/14/2018] [Indexed: 10/16/2022]
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Cunningham VJ, Giakoumatos EC, Ireland PM, Mable CJ, Armes SP, Wanless EJ. Giant Pickering Droplets: Effect of Nanoparticle Size and Morphology on Stability. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:7669-7679. [PMID: 28712294 DOI: 10.1021/acs.langmuir.7b01383] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The interaction between a pair of millimeter-sized nanoparticle-stabilized n-dodecane droplets was analyzed using a high-speed video camera. The droplets were grown in the presence of either poly(glycerol monomethacrylate)-poly(benzyl methacrylate) (PGMA-PBzMA) diblock copolymer spheres or poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate)-poly(benzyl methacrylate) (PGMA-PHPMA-PBzMA) triblock copolymer worms prepared by polymerization-induced self-assembly. The effect of nanoparticle morphology on droplet coalescence was analyzed by comparing 22 nm spheres to highly anisotropic worms with a mean worm width of 26 nm and comparable particle contact angle. Both morphologies lowered the interfacial tension, providing direct evidence for nanoparticle adsorption at the oil-water interface. At 0.03 w/v % copolymer, an aging time of at least 90 s was required to stabilize the n-dodecane droplets in the presence of the worms, whereas no aging was required to produce stable droplets when using the spheres, suggesting faster diffusion of the latter to the surface of the oil droplets. The enhanced stability of the sphere-coated droplets is consistent with the higher capillary pressure in this system as the planar interfaces approach. However, the more strongly adsorbing worms ultimately also confer stability. At lower copolymer concentrations (≤0.01 w/v %), worm adsorption promoted droplet stability, whereas the spheres were unable to stabilize droplets even after longer aging times. The effect of mean sphere diameter on droplet stability was also assessed while maintaining an approximately constant particle contact angle. Small spheres of either 22 or 41 nm stabilized n-dodecane droplets, whereas larger spheres of either 60 or 91 nm were unable to prevent coalescence when the two droplets were brought into contact. These observations are consistent with the greater capillary pressure stabilizing the oil-water interfaces coated with the smaller spheres. Addition of an oil-soluble polymeric diisocyanate cross-linker to either the 60 or the 91 nm spheres produced highly stable colloidosomes, thus confirming adsorption of these nanoparticles.
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Affiliation(s)
- Victoria J Cunningham
- Department of Chemistry, University of Sheffield , Brook Hill, Sheffield, South Yorkshire S3 7HF, U.K
| | - Emma C Giakoumatos
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle , Callaghan, New South Wales 2308, Australia
| | - Peter M Ireland
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle , Callaghan, New South Wales 2308, Australia
| | - Charlotte J Mable
- Department of Chemistry, University of Sheffield , Brook Hill, Sheffield, South Yorkshire S3 7HF, U.K
| | - Steven P Armes
- Department of Chemistry, University of Sheffield , Brook Hill, Sheffield, South Yorkshire S3 7HF, U.K
| | - Erica J Wanless
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle , Callaghan, New South Wales 2308, Australia
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Controlling Pickering Emulsion Destabilisation: A Route to Fabricating New Materials by Phase Inversion. MATERIALS 2016; 9:ma9080626. [PMID: 28773747 PMCID: PMC5509044 DOI: 10.3390/ma9080626] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 07/22/2016] [Accepted: 07/22/2016] [Indexed: 11/30/2022]
Abstract
The aim of this paper is to review the key findings about how particle-stabilised (or Pickering) emulsions respond to stress and break down. Over the last ten years, new insights have been gained into how particles attached to droplet (and bubble) surfaces alter the destabilisation mechanisms in emulsions. The conditions under which chemical demulsifiers displace, or detach, particles from the interface were established. Mass transfer between drops and the continuous phase was shown to disrupt the layers of particles attached to drop surfaces. The criteria for causing coalescence by applying physical stress (shear or compression) to Pickering emulsions were characterised. These findings are being used to design the structures of materials formed by breaking Pickering emulsions.
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Manga MS, Hunter TN, Cayre OJ, York DW, Reichert MD, Anna SL, Walker LM, Williams RA, Biggs SR. Measurements of Submicron Particle Adsorption and Particle Film Elasticity at Oil-Water Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:4125-4133. [PMID: 27035684 DOI: 10.1021/acs.langmuir.5b04586] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The influence of particle adsorption on liquid/liquid interfacial tension is not well understood, and much previous research has suggested conflicting behaviors. In this paper we investigate the surface activity and adsorption kinetics of charge stabilized and pH-responsive polymer stabilized colloids at oil/water interfaces using two tensiometry techniques: (i) pendant drop and (ii) microtensiometer. We found, using both techniques, that charge stabilized particles had little or no influence on the (dynamic) interfacial tension, although dense silica particles affected the "apparent" measured tension in the pendent drop, due to gravity driven elongation of the droplet profile. Nevertheless, this apparent change additionally allowed the study of adsorption kinetics, which was related qualitatively between particle systems by estimated diffusion coefficients. Significant and real interfacial tension responses were measured using ∼53 nm core-shell latex particles with a pH-responsive polymer stabilizer of poly(methyl methacrylate)-b-poly(2-(dimethylamino)ethyl methacrylate) (pMMA-b-pDMAEMA) diblock copolymer. At pH 2, where the polymer is strongly charged, behavior was similar to that of the bare charge-stabilized particles, showing little change in the interfacial tension. At pH 10, where the polymer is discharged and poorly soluble in water, a significant decrease in the measured interfacial tension commensurate with strong adsorption at the oil-water interface was seen, which was similar in magnitude to the surface activity of the free polymer. These results were both confirmed through droplet profile and microtensiometry experiments. Dilational elasticity measurements were also performed by oscillation of the droplet; again, changes in interfacial tension with droplet oscillation were only seen with the responsive particles at pH 10. Frequency sweeps were performed to ascertain the dilational elasticity modulus, with measured values being significantly higher than previously reported for nanoparticle and surfactant systems, and similar in magnitude to protein stabilized droplets.
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Affiliation(s)
- Mohamed S Manga
- School of Chemical and Process Engineering, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Timothy N Hunter
- School of Chemical and Process Engineering, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Olivier J Cayre
- School of Chemical and Process Engineering, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - David W York
- School of Chemical and Process Engineering, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Matthew D Reichert
- Department of Chemical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Shelly L Anna
- Department of Chemical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Lynn M Walker
- Department of Chemical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Richard A Williams
- School of Chemical and Process Engineering, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, United Kingdom
- Heriot-Watt University, George Heriot Wing , Edinburgh, EH14 4AS, United Kingdom
| | - Simon R Biggs
- School of Chemical and Process Engineering, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, United Kingdom
- School of Chemical Engineering, The University of Queensland , Brisbane, Queensland 4072, Australia
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Morse AJ, Giakoumatos EC, Tan SY, Webber GB, Armes SP, Ata S, Wanless EJ. Giant pH-responsive microgel colloidosomes: preparation, interaction dynamics and stability. SOFT MATTER 2016; 12:1477-1486. [PMID: 26648408 DOI: 10.1039/c5sm02450a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The interactions of two oil droplets grown in the presence of swollen, lightly cross-linked cationic poly(tert-butylamino)ethyl methacrylate (PTBAEMA) microgels was monitored using a high-speed video camera. Three oils (n-dodecane, isopropyl myristate and sunflower oil) were investigated, each in the absence and presence of an oil-soluble cross-linker [tolylene 2,4-diisocyanate-terminated poly(propylene glycol), PPG-TDI]. Adsorption of the swollen microgel particles was confirmed by interfacial tension, interfacial elasticity and dilational viscosity measurements on single pendant oil droplets, and assessment of the oscillatory dynamics for coalescing droplet pairs. Like the analogous bulk emulsions, particle adsorption alone did not prevent coalescence of pairs of giant Pickering emulsion droplets. However, prior addition of surface-active PPG-TDI cross-linker to the oil phase results in the formation of highly stable microgel colloidosomes via reaction with the secondary amine groups on the PTBAEMA chains. Colloidosome stability depended on the age of the oil-water interface. This reflects a balance between the adsorption kinetics of the PPG-TDI cross-linker and the microgel particles, each of which must be present at the interface to form a stable colloidosome. Colloidosome formation was virtually instantaneous in n-dodecane, but took up to 120 s in the case of isopropyl myristate. The impact of an acid-induced latex-to-microgel transition on the interaction of giant colloidosomes (originally prepared at pH 10 using isopropyl myristate) was also studied. This acid challenge did not result in coalescence, which is consistent with a closely-related study (A. J. Morse et al., Langmuir, 2014, 30(42), 12509-12519). No evidence was observed for inter-colloidosome cross-linking, which was attributed to retention of an aqueous film between the adjacent pair of colloidosomes.
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Affiliation(s)
- Andrew J Morse
- Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, South Yorkshire S3 7HF, UK
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Bournival G, de Oliveira e Souza L, Ata S, Wanless EJ. Effect of alcohol frothing agents on the coalescence of bubbles coated with hydrophobized silica particles. Chem Eng Sci 2015. [DOI: 10.1016/j.ces.2015.03.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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12
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Colloidosomes: Synthesis, properties and applications. J Colloid Interface Sci 2015; 447:217-28. [DOI: 10.1016/j.jcis.2014.11.058] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 11/21/2014] [Accepted: 11/21/2014] [Indexed: 11/21/2022]
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Piao SH, Kwon SH, Zhang WL, Choi HJ. Celebrating Soft Matter's 10th anniversary: stimuli-responsive Pickering emulsion polymerized smart fluids. SOFT MATTER 2015; 11:646-654. [PMID: 25515644 DOI: 10.1039/c4sm02393e] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The Pickering emulsion process is an important and interesting way of forming hybrid soft matter particles stabilized by solid particles as surfactants instead of the extensive use of conventionally available organic surfactant molecules. This Highlight briefly reviews stimuli-responsive polymer/inorganic hybrid materials fabricated by Pickering emulsion polymerization along with the rheological characteristics of their electrorheological and magnetorheological smart fluids under electric and magnetic fields, respectively.
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Affiliation(s)
- Shang Hao Piao
- Department of Polymer Science and Engineering, Inha University, Incheon, 402-751, Korea.
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