Micro and Nano Gels
Beschreibung
Micro and Nano Gels provides comprehensive interdisciplinary knowledge of micro/nano gels, discussing fundamental synthesis techniques, unique physicochemical properties and their assemblies (e.g. interfacial behaviors, behavior at oil/water or solid interfaces, colloidal packing, and internal morphologies), and innovative applications as adhesives, sensing agents, drug delivery vehicles, tissue scaffolds, optical devices, separation devices, catalytic reactors, and environmental remediation agents.
The book discusses recent advances on amphiphilic random copolymer micelles, focusing on the design, controlled self-assembly and dynamic self-sorting, and functional materials of random copolymer micelles in water. The book also reviews advances for both template-free and -based synthetic methods of nanogels and microgels, covering their mechanisms and enclosing building blocks, as well as advantages and disadvantages of different synthetic routes. Readers will find information on recent developments in microgel characterization using the most advanced tools available, notably scattering and microscopy techniques with nanoscale resolution.
Contributed to by top theoretical and experimental researchers in the field, Micro and Nano Gels includes information on:
* How to combine experimental scattering techniques, such as small-angle scattering and neutron reflectometry, with in silico computer simulations to characterize the structure and response of soft compressible microgels
* Nanostructure and dynamic behavior of microgels using high-speed atomic-force microscopy
* Dynamics of microgels and their pastes with varying concentrations of microgels evaluated using dynamic light scattering
* Simulations of soft colloids and the applicability of different network models for mesoscale studies
Micro and Nano Gels is an essentiala valuable reference on the subject for chemists and materials scientists to not only propel the advancement of pre-existing applications in such as coatings and cosmetics, but also facilitate the development of unprecedented applications.
Weitere Details
Weitere Ausgaben
Andere Ausgaben
Personen
Prof. Daisuke Suzuki obtained his PhD from Keio University (2007), before he went on to conduct postdoctoral studies at the University of Tokyo (2007-2009) as a JSPS research fellow (PD). He started his independent research career at Shinshu University in 2009 as a tenure-track Assistant Professor, where he was promoted to Associate Professor in 2013. He is a research representative of the Core Research for Evolutional Science and Technology (CREST) project. His current research is focused on the design, synthesis, and assembly of soft hydrogel and elastomer microspheres. His awards include the SPSJ Award for outstanding papers in Polymer Journal (sponsored by ZEON), the Award for Encouragement of Research in Polymer Science from the Society of Polymer Science (Japan), and the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Young Scientists Prize (Japan).
Inhalt
PART ONE INTRODUCTION AND PERSPECTIVE
1 Soft Microgels and Nanogels from a Physico-Chemical Perspective
2 Perspective on the Translational Potential of Responsive Micro- and Nanogels
PART TWO SYNTHESIS
3 Amphiphilic Random Copolymer Micelles: Design, Self-Assembly, and Functional Materials
3.1 Introduction
3.2 Design and Synthesis of Amphiphilic Random Copolymers
3.3 Self-Assembly of Amphiphilic Random Copolymers
3.4 Self-Sorting and Co-Self-Assembly of Binary Mixtures
3.5 Self-Healing and Selectively Adhesive Hydrogels
3.6 Functional Nanoaggregates
3.7 Conclusion
4 Advances in Synthesis of Functional Colloidal Gels
4.1 Introduction
4.2 Template-Free Synthesis Methods
4.3 Template-Based Synthesis Methods
4.4 Conclusions
PART THREE CHARACTERIZATION
5 Polymeric Microgels: Insights from Light Scattering, Electron Microscopy, and Optical Superresolution Techniques
5.1 Outline
5.2 COMMON THERMOSENSITIVE PNIPAM MICROGELS
5.3 CHARACTERIZATION TECHNIQUES FOR MICROGELS
5.4 CASE STUDIES
5.5 CONCLUSIONS
6 Formation and Shear Yielding Dynamics of Poly(N-isopropylacrylamide) Based Colloidal Gels
6.1 Introduction
6.2 Single microgel properties
6.3 Criteria of colloidal gelation
6.4 Shear yielding behavior of dilute colloidal gels
6.5 Conclusions
7 Structural characterization of microgels by means of neutron scattering, reflectometry, and computer simulations
7.1 Softness
7.2 Principles of small-angle scattering
7.3 In silico microgels
7.4 Microgel architecture in dilute suspensions
7.5 Microgel architecture in concentrated suspensions
7.6 Determination of the microgel elastic moduli
7.7 Microgel architecture at the interface studied by neutron reflectometry
7.8 Final remarks and outlooks
8 Dynamic and direct visualization of the nanostructure and functions of microgels via high-speed atomic force microscopy
8.1 Introduction
8.2 Evaluation of the inhomogeneous nanostructure in microgels
8.3 Real-time visualization of the microgel function
8.4 Surface characterization of microgels using force?indentation curves
8.5 Outlook
9 The analysis of the dynamics of microgels and their assemblies using light scattering techniques
9.1 Introduction
9.2 Model Microgels
9.3 Dilute Concentration Region
9.4 Intermediate Concentration Region
9.5 High Concentration Region
9.6 Conclusions
10 Computer Simulations of Nano- and Microgel Systems
10.1 Introduction
10.2 Nano- and microgels at the mesoscale
10.3 Nano- and microgels at other scales
10.4 Outlook
11 Electrophoresis of micro/nano gels
11.1 Introduction
11.2 Brinkman-Debye-Bueche model
11.3 Electric potential distribution across a gel layer
11.4 Large gel particle with a planar core surface
11.5 Electrophoresis of a spherical gel
11.6 Electrophoretic mobility of a weakly charged spherical gel particle
11.7 Relaxation effect
11.8 pH-dependent electrophoretic mobility of a gel particle
11.9 Electrophoresis of a gel particle in a polymer gel medium
PART FOUR INTERFACE AND ASSEMBLY
12 Microgel Assembly: From Bulk Phases to Interfaces
12.1 Introduction
12.2 Microgel Assembly in Bulk Phases
12.3 Microgel Assembly at Interfaces
12.4 Influencing Factors of Microgel Assembly at Oil?Water Interfaces
12.5 Microgel Assembly for Stabilizing Biphasic Systems
12.6 Applications of Microgel Assembly at the Interface
12.7 Conclusions and Perspectives
13 Micro/Nano gels at fluid interfaces: single-particle properties and collective behavior
13.1 Introduction
13.2 Single-particle conformation
13.3 Microgel monolayers
13.4 Applications
13.5 Summary and perspective
14 Interfacial behavior of microgels revealed via direct visualization at fluid interfaces
14.1 Introduction
14.2 Formation of a microgel-based thin film via adsorption at the air?water interface
14.3 Deformation of microgels upon adsorption at the air?water interface
14.4 Adsorption behavior of microgels at the air?water interface during evaporation of a sessile droplet
14.5 Development of self-organization behavior of precisely designed micr
1
Soft Microgels and Nanogels from a Physicochemical Perspective
Walter Richtering
Lehrstuhl für Physikalische Chemie II, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany, European Union
The field of soft matter physical chemistry has witnessed remarkable advances in recent decades, with the development and understanding of responsive polymer networks emerging as one of its most fascinating frontiers. Among these innovations, microgels and nanogels stand out as particularly intriguing systems that bridge the gap between macromolecular-scale phenomena and macroscopic properties. These soft crosslinked polymer particles, swollen by the solvent, ranging in size from a few tens of nanometers to several hundred micrometers, have captured the imagination of scientists and engineers alike, offering unique insights into fundamental physicochemical phenomena while simultaneously promising revolutionary applications across diverse fields [1-8].
Building on this foundation, the scientific importance of micro- and nanogels extends far beyond their practical applications. These systems serve as ideal model materials for investigating fundamental physical phenomena that occur on macromolecular and colloidal scales. Their unique architecture - crosslinked polymer networks swollen in a solvent as illustrated in Figure 1.1 - provides an exceptional platform for studying polymer physics, colloid science, and soft matter dynamics in bulk solution and at interfaces.
At the heart of these materials' versatility lies their remarkable ability to respond to various environmental stimuli. Micro- and nanogels can undergo very fast significant volume phase transitions when exposed to changes in temperature, pressure, pH, ionic strength, solvent composition, and specific (bio-)molecular triggers. This responsive behavior has enabled scientists to explore fundamental questions about polymer-solvent interactions, network elasticity, and the interplay between chemical composition and physical properties. The hierarchical relationship between molecular architecture and emergent properties offers an excellent platform for studying structure-property relationships in soft materials.
This responsive nature is intimately connected to the dual character of microgels as soft objects. Due to the presence of solvent within the microgels, they are characterized as soft in two distinct ways: first, microgels can exhibit a soft interaction potential similar to other colloidal systems; second, the microgel itself is soft and deformable while maintaining its structural integrity. This unique combination results in an open structure with high internal mobility of solvent and solute molecules, chain segments, as well as the entire microgel. Consequently, mass exchange with the surroundings differs fundamentally from other colloids: there is no distinct boundary between inside and outside, allowing solvent and solutes to move between the microgel and its environment, which can alter the size and shape of the microgel itself. In essence, microgels are sensitive to their environment; they interact with it by adapting their properties.
Figure 1.1 Microgels (center) combine properties of fundamental types of colloids, that is, rigid particles, flexible macromolecules, and surfactants.
Source: Adapted from [2].
These unique conceptual combinations of structure with chemical and physical properties form the basis for exploring diverse material compositions. Colloidal gel structures can be synthesized from a variety of natural and synthetic polymers, including polysaccharides, proteins, and synthetic polymers, with poly(N-isopropylacrylamide) (PNIPAM) emerging as the most prominent system for fundamental studies [9-13]. Their composition allows for tunability in terms of physical and (biochemical) functionality. While this book mainly focuses on microgels based on synthetic polymers, the underlying principles apply broadly [14].
The evolution of synthetic chemistry has dramatically expanded our control over these versatile materials. Recent advancements have allowed for unprecedented control over the composition and architecture of micro- and nanogels. Scientists have been highly successful in developing methods to synthesize functional microgels with desired properties. Special focus has been given to the selective incorporation of reactive groups into microgels, conjugation with fluorescent labels, enzymes, or glycans, as well as for intra- and inter-particle crosslinking and post-modification reactions. Building on these capabilities, significant efforts have been made to integrate molecular switches and (plasmonic) nanoparticles into microgels to create new temperature-, pH-, light-, and mechano-responsive microgels [15-18]. Further expanding their utility, organocatalysts and enzymes have also been incorporated into microgels to utilize their compartments for modulating chemical reactions [19, 20]. In all these approaches, the selection of functional building blocks along with specific reaction and process conditions determines the overall architecture of the microgel and the local spatial distribution of crosslinkers and functional moieties that influence functionality, shape, stimuli-sensitive swelling, permeability, and deformability.
The synthesis toolkit has grown increasingly sophisticated through the development of advanced techniques. Methods such as controlled radical polymerization, click chemistry, and microfluidic synthesis have enabled researchers to produce microgels with precise size distributions, complex architectures, controlled shapes and internal morphologies, as well as sophisticated responsive behaviors. The synthesis techniques include both template-free and template-based routes along with self-assembly techniques. Colloidal templating combined with precipitation polymerization has been employed to synthesize new model systems as, e.g. spherical or ellipsoidal hollow microgels [21-24]. Complementing these approaches, microfluidics has been used to fabricate hollow and ellipsoidal microgels by polymerizing or crosslinking pre-polymers within aqueous droplets [25]. Additionally, combining a coacervation process with semi-batch precipitation polymerization has proven successful in synthesizing microgels with Janus-like morphology [26].
The field has benefited significantly from the integration of natural and engineering sciences in modern research. By focusing on model-based integrated product-process design, significant progress has been made in understanding and modeling microgel formation, optimizing reactor designs, and enhancing production efficiency [27, 28]. This approach combines experimental and modeling techniques to describe various microgel systems, creating a more comprehensive framework for development [29, 30].
This integrated approach has yielded several key achievements, including the successful transition from microgel-scale design to unit operations aimed at improving production processes. The development of novel process analysis methods and high-throughput screening capabilities has enhanced control over microgel structure and functionality during production [31, 32]. Through investigation of batch reaction processes, such as precipitation polymerization, researchers have created predictive models for synthesizing functional microgels using different reactor types [30]. This advancement has helped bridge the size gap between precipitation polymerization and microfluidic techniques.
Building on these foundations, significant progress has been made in reactor design. The development of template-free continuous synthesis methods has enabled upscaling for functional material applications. In a notable breakthrough, continuous tubular reactors under laminar flow conditions allowed for the first-time synthesis of monodisperse temperature-responsive microgels continuously [28]. Further refinements through data-driven optimization approaches improved PNIPAM microgel synthesis, while high-pressure impinging-jet reactors produced extremely small nanogels under surfactant-free conditions [33].
These technological advances have culminated in a platform technology for sustainably synthesizing tailored microgels with tunable chemical composition, variable sizes (from 50 nm to 100 µm), adjustable crosslinks, diverse shapes (spherical, ellipsoidal, and cylindrical), and morphologies (core-shell, hollow, hollow multi-shell, and Janus). These achievements provide a solid foundation for future innovations in the field.
While these developments have expanded our fundamental understanding and opened new possibilities for applications, challenges remain. Different polymerization techniques and processes are required when different microgel sizes are aimed for. Often these different techniques and processes lead to microgels with different structures, making it difficult to compare properties of microgels that have different sizes. This highlights an area where further progress in the synthesis of microgels is required.
The relationship between structure and function in these materials is both complex and crucial. Chemical structure, size and morphology of the colloidal gels...
