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Kawamoto T, Minato H, Suzuki D. Relationship between π- A isotherms and single microgel/microgel array structures revealed via the direct visualization of microgels at the air/water interface. SOFT MATTER 2024; 20:5836-5847. [PMID: 39007355 DOI: 10.1039/d4sm00640b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
The structures of single microgels and microgel arrays formed at the air/water interface were visualized directly, and their structures correlated with π-A isotherms in order to understand the compression behavior of soft and deformable microgels at this interface. Large microgels (ca. 4 μm) were synthesized so that these can be clearly visualized at the air/water interface, even under high compression, and a series of microgel compression experiments were directly evaluated using a Langmuir trough equipped with a fluorescence microscope. The experiments revealed that upon compressing the microgel arrays at the interface voids disappeared and colloidal crystallinity increased. However, the colloidal crystallinity decreased when the microgel arrays were strongly compressed. In addition, when the structures were observed at higher magnification, it became clear that the single microgel structures, when visualized from above, changed from circular to polygonal upon compressing the microgel array. The results of this study can be expected to improve the understanding of the compression behavior of microgel arrays adsorbed at the air/water interface and will thus be useful for the creation of new functional microgel stabilizers with potential applications in e.g., bubbles and emulsions.
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Affiliation(s)
- Takahisa Kawamoto
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama, 700-8530, Japan.
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
| | - Haruka Minato
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama, 700-8530, Japan.
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
| | - Daisuke Suzuki
- Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama, 700-8530, Japan.
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
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2
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Gerelli Y, Camerin F, Bochenek S, Schmidt MM, Maestro A, Richtering W, Zaccarelli E, Scotti A. Softness matters: effects of compression on the behavior of adsorbed microgels at interfaces. SOFT MATTER 2024; 20:3653-3665. [PMID: 38623629 DOI: 10.1039/d4sm00235k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Deformable colloids and macromolecules adsorb at interfaces as they decrease the interfacial energy between the two media. The deformability, or softness, of these particles plays a pivotal role in the properties of the interface. In this study, we employ a comprehensive in situ approach, combining neutron reflectometry with molecular dynamics simulations, to thoroughly examine the profound influence of softness on the structure of microgel Langmuir monolayers under compression. Lateral compression of both hard and soft microgel particle monolayers induces substantial structural alterations, leading to an amplified protrusion of the microgels into the aqueous phase. However, a critical distinction emerges: hard microgels are pushed away from the interface, in stark contrast to the soft ones, which remain firmly anchored to it. Concurrently, on the air-exposed side of the monolayer, lateral compression induces a flattening of the surface of the hard monolayer. This phenomenon is not observed for the soft particles as the monolayer is already extremely flat even in the absence of compression. These findings significantly advance our understanding of the key role of softness on both the equilibrium phase behavior of the monolayer and its effect when soft colloids are used as stabilizers of responsive interfaces and emulsions.
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Affiliation(s)
- Yuri Gerelli
- Italian National Research Council - Institute for Complex Systems (CNR-ISC) and Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Rome, Italy.
| | - Fabrizio Camerin
- Division of Physical Chemistry, Lund University, P. O. Box 124, SE-22100 Lund, Sweden.
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Maximilian M Schmidt
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Armando Maestro
- Centro de Física de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
- IKERBASQUE-Basque Foundation for Science, Plaza Euskadi 5, Bilbao, 48009, Spain
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Emanuela Zaccarelli
- Italian National Research Council - Institute for Complex Systems (CNR-ISC) and Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Rome, Italy.
| | - Andrea Scotti
- Department of Biomedical Science, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden.
- Biofilms - Research Center for Biointerfaces, Malmö University, SE-205 06 Malmö, Sweden
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3
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Bochenek S, Rudov AA, Sassmann T, Potemkin II, Richtering W. Influence of Architecture on the Interfacial Properties of Polymers: Linear Chains, Stars, and Microgels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:18354-18365. [PMID: 38059308 DOI: 10.1021/acs.langmuir.3c02470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
Surface-active polymers have important applications as effective and responsive emulsifiers, foaming agents, and coatings. In this contribution, we explore the impact of the polymer architecture on the behavior at oil-water interfaces by comparing different poly(N-isopropylacrylamide) (pNIPAM)-based systems, namely, monolayers of linear and star-shaped macromolecules, ultralow cross-linked, regular cross-linked, and hollow microgels. Compression isotherms were determined experimentally as well as by computer simulations. The latter provides information about the conformational changes of the individual macromolecules as well as the interfacial properties of the monolayer, including the surface structure and the density distribution of an ensemble of interacting macromolecules near an interface. Surprisingly, the isotherms of the linear polymer, of the star polymer, and of the ultralow cross-linked microgel have an identical shape that differs from the isotherms of regular and hollow microgels. We introduced the mass fraction of adsorbed polymer, which gives a measure of the polymer segments contributing to the isotherm in relation to the most flexible architecture, i.e., the linear polymer, and allows a comparison of polymers with different architectures. The data demonstrate that increasing the number of cross-links leads to a significantly lower amount of polymer in the proximity of the interface as the increase in cross-linker reduces the deformability or softness of the polymers at the interface. The volume fraction profiles along the normal to the interface are essentially different in the microgel monolayers as compared to those in the linear and star polymer. The profiles through the microgel contact line and their growth upon initial compression are similar to those of the linear chains. Herewith, the profiles through the center of mass practically do not change upon compression. Therefore, the initial growth in the microgel surface pressure reveals the polymer-like behavior and is related to the deformation of the peripheral part of the microgel. Further compression of the microgel monolayer leads to 3D interactions of the microgels within the aqueous side of the interface and soft colloid-like behavior.
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Affiliation(s)
- Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Andrey A Rudov
- DWI - Leibniz Institute for Interactive Materials, 52056 Aachen, Germany, European Union
| | - Tim Sassmann
- DWI - Leibniz Institute for Interactive Materials, 52056 Aachen, Germany, European Union
| | - Igor I Potemkin
- DWI - Leibniz Institute for Interactive Materials, 52056 Aachen, Germany, European Union
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
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Kawamoto T, Yanagi K, Nishizawa Y, Minato H, Suzuki D. The compression of deformed microgels at an air/water interface. Chem Commun (Camb) 2023; 59:13289-13292. [PMID: 37830179 DOI: 10.1039/d3cc03425a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
The compression of deformed hydrogel microspheres (microgels) at air/water interfaces was investigated using a Langmuir-Blodgett trough with simultaneous in situ visualization of the process using a fluorescent microscope. The relationship between the structure of the microgel arrays and the compression behavior was clarified using microgels with different degrees of crosslinking.
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Affiliation(s)
- Takahisa Kawamoto
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
| | - Kohei Yanagi
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
| | - Yuichiro Nishizawa
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
| | - Haruka Minato
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
- Research Initiative for Supra-Materials, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan.
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Akgonullu DZ, Murray BS, Connell SD, Fang Y, Linter B, Sarkar A. Synthetic and biopolymeric microgels: Review of similarities and difference in behaviour in bulk phases and at interfaces. Adv Colloid Interface Sci 2023; 320:102983. [PMID: 37690329 DOI: 10.1016/j.cis.2023.102983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 09/12/2023]
Abstract
This review discusses the current knowledge of interfacial and bulk interactions of biopolymeric microgels in relation to the well-established properties of synthetic microgels for applications as viscosity modifiers and Pickering stabilisers. We present a timeline showing the key milestones in designing microgels and their bulk/ interfacial performance. Poly(N-isopropylacrylamide) (pNIPAM) microgels have remained as the protagonist in the synthetic microgel domain whilst proteins or polysaccharides have been primarily used to fabricate biopolymeric microgels. Bulk properties of microgel dispersions are dominated by the volume fraction (ϕ) of the microgel particles, but ϕ is difficult to pinpoint, as addressed by many theoretical models. By evaluating recent experimental studies over the last five years, we find an increasing focus on the analysis of microgel elasticity as a key parameter in modulating their packing at the interfaces, within the provinces of both synthetic and biopolymeric systems. Production methods and physiochemical factors shown to influence microgel swelling in the aqueous phase can have a significant impact on their bulk as well as interfacial performance. Compared to synthetic microgels, biopolymer microgels show a greater tendency for polydispersity and aggregation and do not appear to have a core-corona structure. Comprehensive studies of biopolymeric microgels are still lacking, for example, to accurately determine their inter- and intra- particle interactions, whilst a wider variety of techniques need to be applied in order to allow comparisons to real systems of practical usage.
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Affiliation(s)
- Daisy Z Akgonullu
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK
| | - Brent S Murray
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK
| | - Simon D Connell
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, UK
| | - Yuan Fang
- PepsiCo, Valhalla, New York, NY, USA
| | | | - Anwesha Sarkar
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK.
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Nishizawa Y, Inui T, Namioka R, Uchihashi T, Watanabe T, Suzuki D. Clarification of Surface Deswelling of Thermoresponsive Microgels by Electrophoresis. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:16084-16093. [PMID: 36441944 DOI: 10.1021/acs.langmuir.2c02742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Although many investigations of thermoresponsive microgels have been reported, their surface properties, which are crucial in colloid science, are still not fully understood. In this study, microgels with surface-localized charged groups were synthesized by precipitation polymerization, and their electrophoretic behaviors were analyzed using a modified version of Ohshima's equation to obtain two surface properties of the soft particles: the softness parameter and the surface charge density. This systematic evaluation allows us to discuss the thermoresponsiveness of the overall microgels and their surfaces separately. Furthermore, the validity of the surface properties obtained from electrophoresis was verified by comparing them with the results of seeded emulsion polymerization in the presence of the microgels and the force-indentation curves obtained via high-speed atomic force microscopy (HS-AFM).
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Affiliation(s)
- Yuichiro Nishizawa
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano386-8567, Japan
| | - Takumi Inui
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano386-8567, Japan
| | - Ryuji Namioka
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano386-8567, Japan
| | - Takayuki Uchihashi
- Department of Physics and Structural Biology Research Center, Graduate School of Science, Nagoya University, Furo-cho, Chiksusa-ku, Nagoya, Aichi464-8602, Japan
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi444-8787, Japan
| | - Takumi Watanabe
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano386-8567, Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano386-8567, Japan
- Research Initiative for Supra-Materials, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 3-15-1 Tokida, Ueda, Nagano386-8567, Japan
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7
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Scotti A, Schulte MF, Lopez CG, Crassous JJ, Bochenek S, Richtering W. How Softness Matters in Soft Nanogels and Nanogel Assemblies. Chem Rev 2022; 122:11675-11700. [PMID: 35671377 DOI: 10.1021/acs.chemrev.2c00035] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Softness plays a key role in determining the macroscopic properties of colloidal systems, from synthetic nanogels to biological macromolecules, from viruses to star polymers. However, we are missing a way to quantify what the term "softness" means in nanoscience. Having quantitative parameters is fundamental to compare different systems and understand what the consequences of softness on the macroscopic properties are. Here, we propose different quantities that can be measured using scattering methods and microscopy experiments. On the basis of these quantities, we review the recent literature on micro- and nanogels, i.e. cross-linked polymer networks swollen in water, a widely used model system for soft colloids. Applying our criteria, we address the question what makes a nanomaterial soft? We discuss and introduce general criteria to quantify the different definitions of softness for an individual compressible colloid. This is done in terms of the energetic cost associated with the deformation and the capability of the colloid to isotropically deswell. Then, concentrated solutions of soft colloids are considered. New definitions of softness and new parameters, which depend on the particle-to-particle interactions, are introduced in terms of faceting and interpenetration. The influence of the different synthetic routes on the softness of nanogels is discussed. Concentrated solutions of nanogels are considered and we review the recent results in the literature concerning the phase behavior and flow properties of nanogels both in three and two dimensions, in the light of the different parameters we defined. The aim of this review is to look at the results on micro- and nanogels in a more quantitative way that allow us to explain the reported properties in terms of differences in colloidal softness. Furthermore, this review can give researchers dealing with soft colloids quantitative methods to define unambiguously which softness matters in their compound.
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Affiliation(s)
- Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - M Friederike Schulte
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Carlos G Lopez
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
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Yoshida H, Furumai H, Ajiro H. Preparation and Characterization of Thermoresponsive Poly( N-vinylisobutyramide) Microgels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5269-5274. [PMID: 35060727 DOI: 10.1021/acs.langmuir.1c02676] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Microgels are soft, adaptive materials exhibiting various properties not only like hydrogels and microparticles but also like macromolecules, colloids, and surfactants. To widen the range of their biomedical and environmental applications, the exploration of an alternative for poly(N-alkylacrylamide)s without potential safety risks is of great importance. In this article, thermoresponsive poly(N-vinylisobutyramide) (PNVIBA) microgels of uniform size were synthesized with NVIBA as a monomer and N,N'-5-oxanonamethyene-bis-N-vinylacetamide as a cross-linker in the presence of sodium dodecyl sulfate by aqueous free radical precipitation polymerization. The introduction of cationic groups into PNVIBA microgels was also accomplished using N-vinylformamide (NVF) as a comonomer and the subsequent conversion of NVF into vinylamine by hydrolysis.
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Affiliation(s)
- Hiroaki Yoshida
- Division of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Hiroya Furumai
- Division of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Hiroharu Ajiro
- Division of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
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10
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Nishizawa Y, Minato H, Inui T, Saito I, Kureha T, Shibayama M, Uchihashi T, Suzuki D. Nanostructure and thermoresponsiveness of poly( N-isopropyl methacrylamide)-based hydrogel microspheres prepared via aqueous free radical precipitation polymerization. RSC Adv 2021; 11:13130-13137. [PMID: 35423887 PMCID: PMC8697349 DOI: 10.1039/d1ra01650d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 03/28/2021] [Indexed: 01/13/2023] Open
Abstract
Thermoresponsive hydrogel microspheres (microgels) are smart materials that quickly respond to external stimuli, and their thermoresponsiveness can be tuned by varying the constituent chemical species. Although uniformly sized microgels can be prepared via aqueous free radical precipitation polymerization, the nanostructure of the obtained microgels is complex and remains unclear so far. In the present study, the nanostructure and thermoresponsiveness of poly(N-isopropyl methacrylamide) (pNIPMAm)-based microgels, which have a volume-transition temperature of ∼43 °C, were evaluated mainly using temperature-controllable high-speed atomic force microscopy. These observations, which are characterized by high spatio-temporal resolution, revealed that the pNIPMAm microgels have a peculiar heterogeneous structure, for example a core-shell and non-thermoresponsive nanostructure in the core region, that originates from the precipitation polymerization process. Furthermore, it was found that the adsorption concentration of the microgels on the substrate is one of the keys for controlling their thermoresponsiveness. These findings can be expected to advance the design of new materials such as thermoresponsive nanosheets and stimuli-responsive coatings.
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Affiliation(s)
- Yuichiro Nishizawa
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Haruka Minato
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Takumi Inui
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Ikuma Saito
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Takuma Kureha
- Graduate School of Science & Technology, Hirosaki University 3, Bunkyo-cho, Hirosaki Aomori 036-8561 Japan
| | - Mitsuhiro Shibayama
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society 162-1 Shirakata Tokai Ibaraki 319-1106 Japan
| | - Takayuki Uchihashi
- Department of Physics, Structural Biology Research Center, Graduate School of Science, Nagoya University Furo-cho, Chiksusa-ku Nagoya Aichi 464-8602 Japan
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Science 5-1 Higashiyama, Myodaiji Okazaki Aichi 444-8787 Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
- Research Initiative for Supra-Materials, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
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