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Jeong HW, Park JW, Lee HM, Choi KH, Lee SJ, Kim JW, Park BJ. Retardation of Capillary Force between Janus Particles at the Oil-Water Interface. J Phys Chem Lett 2022; 13:10018-10024. [PMID: 36264142 DOI: 10.1021/acs.jpclett.2c02499] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Interactions among colloidal particles govern the hierarchical microstructure and its physical properties. Here, optical laser tweezers and Monte Carlo simulations are used to evaluate the effects of azimuthal rotation of Janus particles at the oil-water interface on interparticle interactions. We find that the capillary-induced attractive force between two Janus particles at the interface can be relaxed by azimuthal rotation around the critical separation region, at which the capillary force is ∼0.053 pN. Force relaxation leads to a decrease in capillary force around the critical separation region, resulting in a slight increase in the scaling exponent, compared to the theoretical prediction.
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Affiliation(s)
- Hye Won Jeong
- Department of Chemical Engineering (BK21 Four Integrated Engineering Program), Kyung Hee University, Yongin, Gyeonggi17104, South Korea
| | - Ju Won Park
- Department of Polymer Engineering, The University of Suwon, Hwaseong, Gyeonggi18323, South Korea
| | - Hyang Mi Lee
- Department of Chemical Engineering (BK21 Four Integrated Engineering Program), Kyung Hee University, Yongin, Gyeonggi17104, South Korea
| | - Kyu Hwan Choi
- Department of Chemical Engineering (BK21 Four Integrated Engineering Program), Kyung Hee University, Yongin, Gyeonggi17104, South Korea
| | - Seong Jae Lee
- Department of Polymer Engineering, The University of Suwon, Hwaseong, Gyeonggi18323, South Korea
| | - Jin Woong Kim
- School of Chemical Engineering, Sungkyunkwan University, Suwon, Gyeonggi16419, South Korea
| | - Bum Jun Park
- Department of Chemical Engineering (BK21 Four Integrated Engineering Program), Kyung Hee University, Yongin, Gyeonggi17104, South Korea
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Daradmare S, Lee HS, Seo TS, Park BJ. A surfactant-free approach: Novel one-step ultrasonic nebulizer spray method to generate amphiphilic Janus particles. J Colloid Interface Sci 2022; 627:375-384. [PMID: 35863196 DOI: 10.1016/j.jcis.2022.07.055] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 07/05/2022] [Accepted: 07/09/2022] [Indexed: 11/28/2022]
Abstract
HYPOTHESIS A solvent evaporation-induced phase separation method, which is based on the preferential partitioning of two or more immiscible materials after solvent evaporation on providing heat, has been one of the main strategies for synthesis of Janus particles (JPs). Considering this approach, it should be possible to synthesize surfactant free-JPs in continuous flow by the ultrasonic nebulizer spray method. EXPERIMENTS Two polymers, polystyrene and polymethylmethacrylate, were dissolved in dichloromethane, and droplets of a precursor solution generated by an ultrasonic nebulizer were then conveyed through a borosilicate glass cylinder with two heating zones. The solvent evaporation-induced phase separation occurred in a single flow process, which resulted in the preferential partitioning of two incompatible polymers in the droplets, leading to the formation of the spherical bicompartmental JPs. FINDINGS The successful fabrication of spherical JPs was observed at high polymer concentrations (1.5 and 2.0 wt%), and at elevated temperature (40-75 °C). The fluorescent compartmentalization of JPs was confirmed. Furthermore, the interfacial arrangement of JPs at oil-water interface was studied. A detailed explanation of theoretical prediction of interfacial configurations of JPs was provided. Lastly, the generated JPs were proved as Pickering stabilizers at the oil-water interface.
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Affiliation(s)
- Sneha Daradmare
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin 17104, South Korea
| | - Hag Sung Lee
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin 17104, South Korea
| | - Tae Seok Seo
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin 17104, South Korea.
| | - Bum Jun Park
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin 17104, South Korea.
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Peng F, Xu J, Xu H, Bao H. Electrostatic Interaction-Controlled Formation of Pickering Emulsion for Continuous Flow Catalysis. ACS APPLIED MATERIALS & INTERFACES 2021; 13:1872-1882. [PMID: 33372761 DOI: 10.1021/acsami.0c17857] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Although noble metal or non-noble metal-catalyzed reactions are widely used, it is still difficult to apply these reactions in the large-scale synthesis of chemicals because most of the reactions are carried out by the inefficient batch reaction strategy. Herein, Pickering emulsion-based continuous flow catalysis was utilized to address this problem. Cellulose nanofibers with aldehyde groups (ACNF) were generated through oxidizing C2 and C3 hydroxyl groups of cellulose nanofibers into aldehyde groups by NaIO4, followed by in situ depositing Ag nanoparticles on ACNF to produce Ag-decorated ACNF (ACNF@Ag) via a facile aldehyde-induced reduction method. ACNF@Ag with ∼2 wt % Ag (ACNF@Ag2) has been used to prepare the Pickering emulsion by controlling the electrostatic interaction between ACNF@Ag2 and the oil-water interface via adjusting the pH. It was found that the Pickering emulsion could be generated at a pH around 3.29 and was determined to be the oil-in-water emulsion. The reduction of organic molecules (4-nitrophenol (4-NP), methylene blue (MB), and methyl orange (MO)) was selected as a model reaction to test the reliability of the Pickering emulsion in continuous flow catalysis, which demonstrated very high conversion rates for 4-NP (>98%, 50 h), MB (>99%, 30 h), and MO (>96%, 40 h).
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Affiliation(s)
- Fangjun Peng
- School of Materials Science and Engineering, Wuhan Textile University, Wuhan 430200, China
- State Key Laboratory of New Textile Materials and Advanced Processing Technology, Wuhan Textile University, Wuhan 430200, China
| | - Jie Xu
- School of Materials Science and Engineering, Wuhan Textile University, Wuhan 430200, China
- State Key Laboratory of New Textile Materials and Advanced Processing Technology, Wuhan Textile University, Wuhan 430200, China
| | - Haolan Xu
- Future Industries Institute, University of South Australia, Mawson Lakes Campus, SA 5095, Australia
| | - Haifeng Bao
- School of Materials Science and Engineering, Wuhan Textile University, Wuhan 430200, China
- State Key Laboratory of New Textile Materials and Advanced Processing Technology, Wuhan Textile University, Wuhan 430200, China
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Choi KH, Lee D, Park BJ. Interpretation of interfacial interactions between lenticular particles. J Colloid Interface Sci 2020; 580:592-600. [PMID: 32712468 DOI: 10.1016/j.jcis.2020.07.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/10/2020] [Accepted: 07/10/2020] [Indexed: 11/28/2022]
Abstract
HYPOTHESIS The geometric features of charged particles at a fluid-fluid interface substantially affect their interfacial configurations and interparticle interactions (electrostatic and capillary forces). Because lenticular particles exhibit both spherical and nonspherical surface characteristics, an investigation of their interfacial phenomena can provide in-depth understanding of the relationship between the configuration and the interactions of these particles at the interface. EXPERIMENTS Three types of lenticular particles are prepared using a seeded emulsion polymerization method. Pair interactions at the oil-water interface are directly measured with optical laser tweezers. The numerical calculation of the attachment energy of the particle to the interface is used to predict their configuration behaviors at the interface. FINDINGS The lenticular particles are found to adopt either an upright or inverted configuration that can be determined stochastically. When the interface contacts the truncated boundary or the biconvex boundary, the local interface deformation-induced capillary attraction likely becomes dominant. The contact probability can be estimated on the basis of the attachment energy profile and related to the relative strengths of capillary attraction and electrostatic repulsion between two particles at the interface. Furthermore, possible artifacts in measurements of the pair interactions between nonspherical particles with optical laser tweezers are discussed, depending on their interfacial configurations.
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Affiliation(s)
- Kyu Hwan Choi
- Department of Chemical Engineering, Kyung Hee University, Yongin, Gyeonggi-do 17104, South Korea
| | - Daeyeon Lee
- Department of Chemical and Biolomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Bum Jun Park
- Department of Chemical Engineering, Kyung Hee University, Yongin, Gyeonggi-do 17104, South Korea.
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Ha Eun L, Kyu Hwan C, Xia M, Dong Woo K, Bum Jun P. Interactions between polystyrene particles with diameters of several tens to hundreds of micrometers at the oil-water interface. J Colloid Interface Sci 2020; 560:838-848. [PMID: 31708257 DOI: 10.1016/j.jcis.2019.10.095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/24/2019] [Accepted: 10/24/2019] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS The charged spherical colloidal particles at the fluid-fluid interface experience considerably strong and long-ranged electrostatic and capillary interactions. The contribution of capillary force becomes more significant as the particle size increases beyond a certain limit. The relative strengths of the two competing interactions between the spherical polystyrene particles at the oil-water interface are quantified depending on their size. EXPERIMENTS The studied particles, obtained using the microfluidic method, have diameters of tens to hundreds of micrometers. The scaling behaviors of the commercially available colloidal particles with diameters of ~3 μm are also compared. An optical laser tweezer apparatus is used to directly or indirectly measure the interparticle force. Subsequently, the capillary force that can be attributed to the gravity-induced interface deformation and contact line undulation is calculated and compared with the measured interaction force. FINDINGS Regardless of the particle diameter (~3-330 μm), the measured force is observed to decay as r-4, where r denotes the center-to-center separation, demonstrating that the dipolar electrostatic interaction is important and that the gravity-induced capillary interaction is negligible. Furthermore, numerical calculations with respect to the undulated meniscus confirm that the magnitude of capillary interaction is significantly smaller than that of the measured electrostatic interaction.
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Affiliation(s)
- Lee Ha Eun
- Department of Chemical Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin 17104, South Korea
| | - Choi Kyu Hwan
- Department of Chemical Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin 17104, South Korea
| | - Ming Xia
- Department of Chemical Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin 17104, South Korea
| | - Kang Dong Woo
- Department of Chemical Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin 17104, South Korea
| | - Park Bum Jun
- Department of Chemical Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin 17104, South Korea.
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Choi KH, Kang DW, Kim KH, Kim J, Lee Y, Im SH, Park BJ. Direct measurement of electrostatic interactions between poly(methyl methacrylate) microspheres with optical laser tweezers. SOFT MATTER 2019; 15:8051-8058. [PMID: 31549697 DOI: 10.1039/c9sm01374a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this study, we measured the force of electrostatic interactions between poly(methyl methacrylate) (PMMA) particles dispersed in organic solvent mixtures of cyclohexyl bromide (CHB) and n-decane. Optical laser tweezers were employed to directly measure interactive forces between paired PMMA particles in a CHB medium that contained n-decane in various volume ratios. CHB, having a moderate dielectric constant, provided an environment with a high charge storage capacity. The addition of n-decane lowered the effective refractive index of the medium, which increased the optical trapping efficiency. We also fabricated microscope flow cells with a commonly used UV-curable adhesive and quantified the effects of dissolved adhesive compounds through interactive force measurements and nuclear magnetic resonance analysis. In addition, we studied the impact of CHB dissociation into H+ and Br- ions, which could screen electrostatic interactions.
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Affiliation(s)
- Kyu Hwan Choi
- Department of Chemical Engineering, Kyung Hee University, Yongin 17104, South Korea.
| | - Dong Woo Kang
- Department of Chemical Engineering, Kyung Hee University, Yongin 17104, South Korea.
| | - Kyung Hak Kim
- Department of Chemical Engineering, Kyung Hee University, Yongin 17104, South Korea.
| | - Jiwon Kim
- Department of Bionano Technology, Hanyang University, Ansan 15588, South Korea
| | - Youngbok Lee
- Department of Bionano Technology, Hanyang University, Ansan 15588, South Korea and Department of Chemical and Molecular Engineering, Hanyang University, Ansan 15588, South Korea.
| | - Sang Hyuk Im
- Department of Chemical and Biological Engineering, Korea University, Seoul 02841, South Korea.
| | - Bum Jun Park
- Department of Chemical Engineering, Kyung Hee University, Yongin 17104, South Korea.
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Ballard N, Law AD, Bon SAF. Colloidal particles at fluid interfaces: behaviour of isolated particles. SOFT MATTER 2019; 15:1186-1199. [PMID: 30601564 DOI: 10.1039/c8sm02048e] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The adsorption of colloidal particles to fluid interfaces is a phenomenon that is of interest to multiple disciplines across the physical and biological sciences. In this review we provide an entry level discussion of our current understanding on the physical principles involved and experimental observations of the adsorption of a single isolated particle to a liquid-liquid interface. We explore the effects that a variation of the morphology and surface chemistry of a particle can have on its ability to adhere to a liquid interface, from a thermodynamic as well as a kinetic perspective, and the impact of adsorption behaviour on potential applications. Finally, we discuss recent developments in the measurement of the interfacial behaviour of nanoparticles and highlight open questions for future research.
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Affiliation(s)
- Nicholas Ballard
- POLYMAT - University of the Basque Country (UPV/EHU), Centro Joxe Mari Korta, Avenida de Tolosa 72, 20018, Donostia-San Sebastian, Spain.
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Hunter SJ, Thompson KL, Lovett JR, Hatton FL, Derry MJ, Lindsay C, Taylor P, Armes SP. Synthesis, Characterization, and Pickering Emulsifier Performance of Anisotropic Cross-Linked Block Copolymer Worms: Effect of Aspect Ratio on Emulsion Stability in the Presence of Surfactant. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:254-265. [PMID: 30562037 DOI: 10.1021/acs.langmuir.8b03727] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization is used to prepare epoxy-functional PGMA-P(HPMA- stat-GlyMA) diblock copolymer worms, where GMA, HPMA, and GlyMA denote glycerol monomethacrylate, 2-hydroxypropyl methacrylate, and glycidyl methacrylate, respectively. The epoxy groups on the GlyMA residues were ring-opened using 3-aminopropyltriethoxysilane (APTES) in order to cross-link the worm cores via a series of hydrolysis-condensation reactions. Importantly, the worm aspect ratio can be adjusted depending on the precise conditions selected for covalent stabilization. Relatively long cross-linked worms are obtained by reaction with APTES at 20 °C, whereas much shorter worms with essentially the same copolymer composition are formed by cooling the linear worms from 20 to 4 °C prior to APTES addition. Small-angle X-ray scattering (SAXS) studies confirmed that the mean aspect ratio for the long worms is approximately eight times greater than that for the short worms. Aqueous electrophoresis studies indicated that both types of cross-linked worms acquired weak cationic surface charge at low pH as a result of protonation of APTES-derived secondary amine groups within the nanoparticle cores. These cross-linked worms were evaluated as emulsifiers for the stabilization of n-dodecane-in-water emulsions via high-shear homogenization at 20 °C and pH 8. Increasing the copolymer concentration led to a reduction in mean droplet diameter, indicating that APTES cross-linking was sufficient to allow the nanoparticles to adsorb intact at the oil/water interface and hence produce genuine Pickering emulsions, rather than undergo in situ dissociation to form surface-active diblock copolymer chains. In surfactant challenge studies, the relatively long worms required a thirty-fold higher concentration of a nonionic surfactant (Tween 80) to be displaced from the n-dodecane-water interface compared to the short worms. This suggests that the former nanoparticles are much more strongly adsorbed than the latter, indicating that significantly greater Pickering emulsion stability can be achieved by using highly anisotropic worms. In contrast, colloidosomes prepared by reacting the hydroxyl-functional adsorbed worms with an oil-soluble polymeric diisocyanate remained intact when exposed to high concentrations of Tween 80.
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Affiliation(s)
- Saul J Hunter
- Department of Chemistry , University of Sheffield , Dainton Building, Brook Hill , Sheffield , Yorkshire S3 7HF , U.K
| | - Kate L Thompson
- The School of Materials, University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Joseph R Lovett
- Department of Chemistry , University of Sheffield , Dainton Building, Brook Hill , Sheffield , Yorkshire S3 7HF , U.K
| | - Fiona L Hatton
- Department of Chemistry , University of Sheffield , Dainton Building, Brook Hill , Sheffield , Yorkshire S3 7HF , U.K
| | - Matthew J Derry
- Department of Chemistry , University of Sheffield , Dainton Building, Brook Hill , Sheffield , Yorkshire S3 7HF , U.K
| | - Christopher Lindsay
- Syngenta, Jealott's Hill International Research Centre , Bracknell , Berkshire RG42 6EY , U.K
| | - Philip Taylor
- Syngenta, Jealott's Hill International Research Centre , Bracknell , Berkshire RG42 6EY , U.K
| | - Steven P Armes
- Department of Chemistry , University of Sheffield , Dainton Building, Brook Hill , Sheffield , Yorkshire S3 7HF , U.K
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