This chapter explores the use of patchy particle models to study transient polymer networks (TPNs), with an emphasis on vitrimers. Patchy particles, equipped with bond-swapping mechanisms, offer a versatile framework for capturing the dynamic restructuring of these networks. As examples, we show how using coarse-grained approaches such as Monte Carlo simulations and bond-swapping via the three-body repulsion method makes it possible to investigate the thermodynamics, phase behavior, and viscoelastic properties of vitrimer-like systems. We highlight how these models provide insights into TPNs’ unique dynamics and pave the way for designing adaptable materials. As an example, we discuss how the ideas discussed have been used to design and synthesize a vitrimer-like all-DNA gel in the lab.
Wheat flour dough is a classic soft material comprised of a hierarchy of weakly bonded structures imparting macroscopic properties that strongly depend on how the properties are evaluated. Additional softness arises from the bubbles within the dough. The structure and the dynamics of doughs and other bakery foams are affected by bubble nucleation and growth. A critical bubble volume fraction determines a transition from bubbly liquid to foam, which must be surpassed to attain desired qualities in the baked (thermostabilized) products, particularly the appearance and mechanical properties associated with the network of gas cells. Techniques and models used to elucidate the structure, dynamics and properties of other soft materials are employed to investigate how to control dough processing (in the kitchen or the industrial bakery) to attain optimal eating quality of the baked product.
Fruit and vegetable juices and purées are very common foods obtained by extracting the juice or by cooking and grinding the flesh of fruits or vegetables. This simple preparation allows one to obtain suspensions of soft and deformable plant particles covering a very wide range of textures: from smooth to granular, from fluid to thick, and from low-viscosity Newtonian fluids to highly viscous shear-thinning fluids with a yield stress. In this chapter, preparation of juices and purées is described and the various parameters (namely fruit and vegetable types or processes applied) that affect their properties are discussed. Soft matter physics concepts are used to describe their behavior. Practical applications for formulators and industry are presented, and new techniques that might help to elucidate the behavior of these systems in the future are proposed.
Among natural biopolymers, silkworm silk has exceptional mechanical properties, good biocompatibility and biodegradability. Thus, silk materials are considered to be one of the most promising candidates for wearable devices. This chapter begins by describing the five-level hierarchical structure of silk fiber (Bombyx mori), from the amino acid sequence to the nanofibril network. Next, the properties of natural silk fibers are presented. In addition, the various cross-linking methods involved ranging from regenerated silk fibroin (SF) solutions to meso-reconstructed SF hydrogels or films are discussed in detail, including β-sheet formation, di-tyrosine crosslinking, plasticization and methacrylate modification. Furthermore, mesoscopic-doped hybridized SF-based materials are further discussed. Finally, methods for the preparation of regenerated SF solutions and recipes for the fabrication of various SF-based materials from these solutions are described.
Transient polymer networks are polymer networks cross-linked by reversible bonds. They are very special in that their chemical reactions in the cross-links and/or among network chains allow viscoelasticity and macroscopic flows while remaining connected as a whole. Rheological properties of such reactive polymer networks have long been a topic of interest in polymer science and engineering. In this chapter, dynamical models to describe transient polymer networks are systematically presented in the order in accordance with the nature of the chemical reactions, thereby with special attention to their historical developments. The strategy to combine classical theory of rubber elasticity with kinetics of chemical reactions is stressed. Some of the models are solved, while others await solution. Potential applications and future prospects of these theoretical frameworks are discussed.
Cellulose, as the most abundant and ubiquitous polymeric raw material on Earth, is an important green and renewable resource with attractive properties, and is widely isolated and extracted from plants on a large scale, such as wood, cotton, and cereal, or generated from bacteria. The interest in cellulose and its modification as cellulose-based composites has been rapidly increasing. This chapter discusses the fundamentals and background of cellulose, as well as the modification of cellulose-based composites. Various methodologies to obtain cellulose and cellulose-based composites with diverse structural shapes are presented. The challenges in the practical preparation of cellulose-based materials and the corresponding solutions are also emphasized.
Natural biopolymers have attracted extensive research interest in the past decades for application in flexible energy conversion and storage devices, which has been largely motivated by the rapid development of Internet-of-Things (IoT) devices and the increasing demand for portable power sources to enable autonomous functionality. Various natural biopolymers, such as cellulose, chitin/chitosan, starch, silk, gelatin, agarose, and lignin, have been explored to date. Natural biopolymers have several prominent advantages over synthetic polymers, including low cost, high abundancy, excellent recyclability, mechanical flexibility, biodegradability and biocompatibility. Natural biopolymers, being used alone or in combination with synthetic polymers, have attracted increasing research attention for various functional components in flexible energy devices, including lightweight and flexible substrates, electrode materials, templates for designing hierarchical structures, and host polymers/gelling agents for electrolytes. In particular, natural biopolymers have been demonstrated as promising candidates for high-performance gel electrolytes with decent ionic conductivity, high flexibility, and electrochemical stability. This chapter presents the progress in natural biopolymer-based flexible energy conversion and storage devices, such as solar cells, thermoelectric devices, supercapacitors, and batteries. The key challenges and future perspectives are also discussed by the end of the chapter to shed light on the future research and development.
As the main building materials of tofu, it is essentially important to control the gelation of soy proteins during tofu processing. This chapter first discusses soy protein aggregation as influenced by environmental conditions during soymilk heating and its impact on the development of the gel network. The influences of coagulant concentration, coagulation method, protein concentration and temperature on gelation are further introduced. Furthermore, kinetics of soy protein aggregation and gelation are introduced followed by a brief discussion of the influence of protein composition on gel quality.
We demonstrate that stirred style yoghurt, whipped cream and melted cheese can each be described as a soft glass. Using some very simple models, we can demonstrate that the functional and shelf life properties of these foods are dictated by the underlying colloidal and macroscopic behaviours, rather than the many chemical nuances.
This chapter explores recent advances in scattering techniques for the characterization of food emulsions, an essential area of research in food science and technology. We begin with an overview of food emulsions, and a brief discussion of scattering phenomena and scattering techniques that offer insights into the stability and microstructure of emulsion-based foods. Dynamic Light Scattering (DLS) and Diffusing Wave Spectroscopy (DWS) are examined for their capabilities to assess particle size distribution and dynamic behavior in emulsions. Next, we discuss Small Angle X-ray Scattering (SAXS), Wide Angle X-ray Scattering (WAXS), and Ultra Small Angle X-ray Scattering (USAXS), focusing on their applications in elucidating the structural characteristics of crystallized lipids at various length scales, both within emulsion droplets and at oil–water interfaces. Finally, we highlight Small Angle Neutron Scattering (SANS) and Ultra Small Angle Neutron Scattering (USANS) as powerful tools for examining the nano- and microstructures of emulsions and emulsion gels. Examples illustrate their role in revealing information about the thickness of interfacial layers formed by emulsifiers and the coverage of interfaces by emulsifier molecules.
To bring together professionals in the food industry and soft-matter physicists, this chapter is intended to serve as an introduction to the fundamental concepts of soft materials physics in the context of food systems. Soft materials are characterised by their complex material properties, which arise from microstructural interactions and result in a wide variety of flow and deformation behaviours. By understanding how the microstructural elements of a food system dictate its material properties, we can gain the ability to predict and ultimately control macroscopic performance (e.g., texture and stability) during processing, storage, and consumption. In this chapter we present the key rheological behaviours observed in soft materials physics. Next, the microstructural elements and interactions that give rise to food behaviours are introduced. Finally, non-continuum phenomena are discussed in relation to microstructural properties. Examples of how soft materials physics can help understand and control the functionality and quality of food products, such as gels, emulsions, foams, and doughs, are presented throughout. This chapter forms a foundation for the rest of the collected work, which will explore the current state of knowledge and challenges of major food systems from a soft matter perspective.
Fat crystallization plays a paramount role in defining the structure, sensory properties, and stability of complex multiphase food products. Gas, liquid, and solid phases dispersed in fat influence its crystallization by increasing the surface area aided by surface-active molecules and confinement. In this chapter, we examine the current state of the art concerning the roles of dispersed phases (e.g., gas, liquid, and solid) and surface-active molecules in the crystallization, microstructure formation, and the resulting physical properties and stability of multiphase fat food systems.
The macroscopic rheological properties of colloidal networks of proteins, polysaccharides, fat crystals and oleogelators are a function of the amount of network material present, the size and shape of the colloids and their aggregates and the strength of their inter-colloidal interactions. Here we will outline the development of quantitative models describing the relationships between the nano- and mesoscale structures of colloidal and polymer protein hydrogels and lipid oleogels and their macroscopic rheological and mechanical properties. These quantitative models will be used to showcase their usefulness in a variety of systems, from edible fats and oleogels to whey protein isolates and casein gels. The successful development of new food products requires a fundamental knowledge of the relationship between structures at different length scales and their physical properties.
Vitrimer materials combine the mechanical stability of thermosets at low temperatures with the flow and reprocessability of thermoplastics at high temperatures, offering excellent self-healing and reprocessability. This chapter reviews the application of molecular dynamics (MD) simulation techniques in the study of these materials. Through MD simulations, the bond exchange mechanism is elucidated at the molecular level, revealing the distinct regulatory effects of bond exchange energy barriers and temperature on the viscoelastic behavior of the materials. By employing MD analysis techniques such as bond autocorrelation functions, self-intermediate scattering functions, mean squared displacement, and end-to-end vector relaxation, a multi-scale structure–property relationship model has been developed, spanning from bond exchange kinetics to segmental motion and ultimately to whole-chain relaxation. Stress–strain curves are derived from tensile deformation simulations to investigate the mechanical properties of the materials. Furthermore, by adjusting simulation parameters such as temperature, potential barriers, and crosslinking density, the structure–property relationships in vitrimer materials are revealed. In addition, new simulation models have been designed and developed to guide the experimental design of material structures and the development of high-performance vitrimer materials.
The technology of triboelectric nanogenerators (TENGs) has risen to prominence as a viable solution for sustainable energy capture, facilitating the conversion of mechanical energy into electrical energy via the triboelectric phenomenon. Recently, there has been a notable surge of interest in integrating natural biopolymer materials into TENGs, attributed to their intrinsic biodegradable, biocompatible, and eco-conscious properties. When used in TENGs, these materials not only exhibit effective triboelectric performance but also offer additional benefits, such as mechanical flexibility, low cost, and ease of processing. By leveraging the unique properties of biopolymers, TENGs can be designed for a wide array of applications, spanning from wearable electronics and healthcare monitoring gadgets to environmental sensors and motion tracking devices. Furthermore, the integration of these biopolymers promotes the progress of eco-friendly and sustainable technologies, aligning with global goals for environmental conservation and renewable energy utilization. This chapter highlights recent advancements, challenges, and future prospects in the realm of biopolymer-integrated multifunctional TENGs, emphasizing their capacity to revolutionize the domain of self-powered systems and sustainable energy solutions.
Humans have intuitively linked food production to final product properties long before systematic experiments. Over the last century, scientists and developers have deepened our understanding of the physics and chemistry of food production, oral processing, and sensory perception. This chapter reviews the evolution of food property measurements, focusing on pivotal papers and advanced techniques for rheological and tribological measurements. We cover psychophysics, standard rheological measurements, and advanced techniques like microfluidic- and surface-based and imaging + rheology methods. Emphasis is placed on analytical measurements and their relevance to industrial R&D, urging readers to critically evaluate the practicality of these techniques for manufacturing consumer goods.
Foods are complex materials with structures ranging from the nano- to the macroscale, including structural elements such as lipid droplets, air bubbles, and particles, entrapped in a hydrocolloid-based matrix. These structures influence food properties and textures, which are crucial during consumption, particularly in food oral processing (FOP), where food undergoes significant structural changes. While texture attributes like hardness are easily measurable and can be linked to FOP, others like stickiness are less understood, yet critically impact consumer preferences and safety. Stickiness can be desirable or problematic, depending on the population, such as dysphagia patients. This chapter explores the stickiness as a texture attribute using a soft matter lens on food, highlighting the challenges and strategies for controlling this texture attribute.
Implantable systems for biomedical research and clinical care have become a flourishing field in both academic and industrial settings. Many existing and envisioned classes of implantable biomedical devices require high performance electronics/sensors, which must be flexible and biocompatible. Natural biopolymers are well-suited for use in these systems owing to their inherent flexibility, biocompatibility and biodegradability. This chapter will introduce the applications of natural biopolymer-based materials with different strategies for implantable electronics. It will also highlight the main challenges and possible solutions for their practical use in implantable systems.
Molecular simulation continues to make an important contribution to the study of complex food systems, complementing experimental efforts to understand and manipulate food structure. The past few years have seen an increase in the complexity of systems studied, with large multicomponent systems routinely studied. For protein systems there have been advances in the simulation of protein-based Pickering emulsifier systems, such as zein particles, both as emulsifiers and as carriers of food additives such as phenolic antioxidants. Similarly, studies have moved beyond investigating just the effects of thermal processing on protein structure to include novel processing techniques involving electrical fields and high pressure and to find out how they can induce protein denaturation. The advances in the simulation of triglycerides have been particularly notable. The widespread application of coarse-graining of triglyceride structures enabled a detailed study of triglyceride crystallization and melting not yet obtained with conventional all-atom molecular dynamics. Recent polysaccharide simulations have focused on understanding the solution structure of the molecules. Simulation of inclusion complexes between starch and fatty acids that alter starch functionality and limit digestibility has revealed the importance of the starch helical secondary structure in this process. Finally, the mechanisms of the sol–helix transition during gelation of carrageenans and the adsorption of pectin structural domains at oil–water interfaces are discussed.
