最新刊期
卷 38 ， 期 2 ， 2025
- 摘要：Polymer nanocomposites (PNCs) have demonstrated significant potential and promising development prospects in numerous fields, owing to their exceptional mechanical properties and multifunctionality. However, the inadequate understanding of the confined dynamics and rheology of PNCs poses challenges in manipulating their properties and results in immature processing and preparation technologies. This monograph aims to summarize the recent advancements in the confined dynamics and rheology of PNCs and explain the relationship between confined dynamics, including multiscale molecular dynamics and multiscale particle dynamics, with linear rheology in PNCs. It also discusses the research methods, theoretical foundations, and future directions.关键词：Polymer nanocomposites;Nanoparticles;Confined dynamics;Rheology517|1007|0更新时间：2025-01-23
- 摘要：Accurate comprehension of the mechanical properties of polymers at the nanoscale is essential for their application as functional materials or structural templates in nanodevices. Previous research has identified significant disparities in the mechanical properties of nanoscale polymers compared to bulk materials due to the nanoconfinement effect. However, conventional commercial testing instruments are often inadequate for evaluating nanoscale polymer materials, which poses a considerable challenge to fully grasp the complex viscoelastic mechanics and its underlying mechanism under nanoconfinement. In recent years, we have realized the direct observation of the mechanical properties of supported polymer nanofilms by constructing a pressure- and temperature-controllable mechanical testing system based on pneumatic pressure action and high-speed photography. Using this system, the authors’ group has conducted a deeper study of the mechanical properties (including elasticity, viscoelasticity, and viscoplasticity, etc.) of both rubber elastomers and thermoplastic films with thicknesses of less than 100 nm when confined to the air or polymer interface. The results reveal novel features of the mechanical properties of polymer films under the nanoconfinement effect. This monograph article briefly summarizes the current research status and recent results in the field of viscoelastic properties of the nanoconfined polymers and looks forward to the future development trend.关键词：Nanoscale polymer film;Mechanical property;Nanoconfinement;Viscoelasticity;Bulging test453|260|0更新时间：2025-01-23
- 摘要：Since the beginning of the 21st century, flexible electronics have undergone rapid development due to the increasing demand for wearable devices, soft robots, and smart textiles. In this context, gallium-based liquid metals (LMs) have gained wide popularity in the field of flexible electronics due to their excellent conductivity, chemical stability, and biocompatibility. However, the extremely high surface tension and low viscosity of LMs result in poor adhesion to most substrates, limiting their direct use. The dispersion of LMs in polymer matrices to form liquid metal polymer composites (LMPCs) not only avoids the aforementioned problem but also exhibits unique thermal conductivity, electrical conductivity, and mechanical properties. Consequently, these emerging soft multifunctional composites are widely applied in current technologies such as wearable devices, stretchable electronic products, soft robots, and supercapacitors. To effectively prepare and develop these unique composites, it is necessary to understand their rheological behavior. This article presents a summary of recent research progress on the rheological behavior of LMPCs. The main focus is on the influence of the rheological behaviour of LMPCs with different polymer matrices on their mechanical and electrical conductivity properties. Additionally, this article identifies the opportunities and challenges currently facing this field.关键词：Liquid metals;Polymer composite;Rheological behavior;Mechanical property;Electrical conductivity428|491|0更新时间：2025-01-23
- 摘要：Poly(ionic liquid)s (PILs) are new types of polyelectrolytes, which are synthesized by ionic liquid monomer polymerization. Different from traditional polyelectrolytes, PILs contain large-size fluorinated counterions and thus they possess a natural hydrophobicity and a counterion migration characteristic in non-aqueous state. These characteristics endow PILs with potential as the next generation non-aqueous polyelectrolyte-based electrorheological (ER) materials, which can overcome the problems of traditional polyelectrolyte-based ER materials, including high leakage current, thermal instability, and dielectric breakdown caused by adsorbed water. To highlight PILs as potential next generation ER materials, we review the research progress of ER effect of PILs in the past decade including the ER effect of linear PILs, cross-linked PILs, composite PILs, and ion-covalent organic framework materials. In particular, the review gives a discussion about the relationship between the ER effect of PILs and their structure in order to provide a guide for the design and preparation of high-performance PILs-based ER materials in the future.关键词：Poly(ionic liquid)s;Electrorheological fluid;Electrorheological effect785|1269|0更新时间：2025-01-23
- 摘要：Mechanically interlocked polymers (MIPs) are a unique class of topological materials composed of mechanical bonds, where the rich intramolecular motions impart the materials with distinctive properties. Rheology, as an efficient tool for elucidating the structure-properties relationships of polymeric materials, has shown particular appeal in the study of MIPs. This paper provides a focused review of the latest advances in using rheological methods to explore the structure-property relationships of MIPs. The review first examines the microscopic motions of mechanical bonds within MIPs, followed by an analysis of how these mechanical bonds influence the mechanical behaviors and viscoelasticity of mechanically interlocked materials. Finally, the challenges in the rheological study of MIPs are briefly summarized, and future directions for related research are discussed.关键词：Mechanically interlocked polymers;Rheology;Motion of mechanical bonds;Structure-property relationship;Topological polymers995|581|0更新时间：2025-01-23
- 摘要：Rheology is a powerful tool for probing molecular dynamics of polymers via characterizing viscoelastic responses to external stress or strain, while the multiple-quantum (MQ) and fast-field-cycling (FFC) nuclear magnetic resonance (NMR) techniques can directly quantitatively reveal the hierarchical dynamics of polymers at the molecular level. Herein, a combination of rheology and NMR can provide deep insights into the comprehensive dynamic characteristics of polymers, and thus to establish the relationship between macroscopic performance and microscopic molecular dynamics, providing experimental evidences for the further development of polymer dynamics theories. In this article, we firstly give a brief introduction to the polymer dynamics theories, and then we detail the fundamental principles and experimental methods of MQ and FFC NMR for quantitative extraction of molecular dynamics information, which are correlated well with rheology results. Lastly, we show some examples of using a combination of NMR and rheology to study different complex systems including supramolecular rubbers, hydrogels, nanocomposites, and so on.关键词：Multiple-quantum NMR;Fast-field-cycling;Rheology;Polymer dynamics;Supramolecules310|2477|0更新时间：2025-01-23
- 摘要：The construction of molecular constitutive models is an important way to understand the relationship between microstructure dynamics and macroscopic rheological behavior. From the perspective of non-equilibrium statistical physics, significant progress has been made in the study of rheological constitutive models. The calculated molecular structures include but are not limited to linear chains, star chains, H chains, pom-pom chains, comb chains, bottle-brush chains, tree-like chains, and randomly branched chains, etc. The rheological constitutive models of polymers reviewed in this article, although the names of these models are not related due to historical reasons, models themselves are developed from simplicity to complexity. We will start from the perspective of the Onsager variational principle to introduce the problems and assumptions addressed by each linear viscoelastic model, in order to present the development path of the model more clearly. The success of linear viscoelastic models enables us to deeply understand how structure affects performance, laying a solid foundation for the construction of nonlinear viscoelastic models. By combining linear viscoelastic spectra with nonlinear relaxation mechanism, the constructed nonlinear model can be well validated in rheological testing, such as oscillatory shear, start-up shear/extension, and step shear in experiments. However, due to the complexity of dynamic intermolecular interactions and nonlinear coupling, there are still significant challenges in constructing models for the dynamics of structures, such as chain adsorption, dynamic reactions, and slide-ring sliding.关键词：Branched polymer;Segment dynamics;Constitutive equation;Viscoelasticity;Nonlinearity507|1302|0更新时间：2025-01-23
- 摘要：Associative polymers (APs), due to their unique dynamic behaviors, show significant potential in fields such as self-healing, shape memory, and rheological modification. The presence of associative interactions leads to a coupling between strand motion and associative reactions, which not only broadens the application of APs, but also adds complexity to their processing. Developing a rheological theory for APs is essential for understanding their viscoelastic properties at the molecular level. Such insights not only guide processing and application conditions, but also help explore new applications, thereby further expanding the utility of APs across various fields. This paper reviews and analyzes recent advances in the rheological theories of APs, particularly focusing on the sticky Rouse model (SRM). The SRM extends the fundamental Rouse model by incorporating associative interactions as an apparent friction coefficient based on the mean-field assumption. Through molecular simulations and relevant experimental results, we validate the applicability and limitations of the mean-field assumption in the SRM. Future directions for rheological theories concerning APs are also discussed in light of current research.关键词：Associative polymers;Sticky Rouse model;Molecular simulations;Linear viscoelasticity502|268|0更新时间：2025-01-23
- 摘要：Since the concept of vitrimer with both thermosetting and thermoplastic advantages was proposed, research on vitrimer has shown broad development prospects and has received widespread attention from the academic community. The performance, reprocessing ability and self-repairing properties of vitrimers are closely related to their rheological properties. This paper reviews the current status and progress of rheological research on vitrimers, aiming to summarize and analyze the main methods of rheological research on vitrimers and explore the main factors affecting their rheological properties. The role of rheological research in promoting their application in areas such as high-performance coatings is further discussed. It also proposes key issues that need to be solved in the current research on rheological research of vitrimers, and provides ideas and suggestions for subsequent research.关键词：Vitrimer;Rheology;Characterization method;Influencing factor543|1870|0更新时间：2025-01-23
- 摘要：Polymer gels, a system composed of three-dimensional network and solvent, have unique properties between solid and liquid, and show important application prospects in the fields of food, daily necessities, bio-tissue engineering, and flexible electronic skin, etc. Rheology is a science that studies the flow and deformation of substances. The rheological approach is an important tool for understanding the network structure and deformation law of polymer gels, providing an important perspective for revealing the microscopic mechanism of gel network, laying an experimental foundation for the establishment of relationship between network structure and rheological properties, and providing a theoretical support for the design and preparation of novel multifunctional gel materials. This paper firstly reviews the rheological research methods of polymer gel network structure, then systematically elaborates the design principles and rheological properties of high strength and tough gel networks in recent years, and finally makes an outlook on the application of rheological coupling technology in analyzing the network structure of polymer gels.关键词：Polymer gels;Network structure;rheology behavior876|1907|0更新时间：2025-01-23
- 摘要：Polymer dynamics span the range from the segmental scale involving only a few repeated units to relaxation of the entire macromolecular chain (tens of nanometers). When it was confined in nano to micro scales, its dynamics, viscoelasticity and rheology behaviors would deviate from its bulk behavior. Such deviation makes it more complex in processing and results in unpredictable performance at nano and micro scales. Here in this review, the process of single chains through nanopore and polymer melts under confinement of different dimension were summarized. Special attention was drawn on contribution of scale, interaction, conformation of confined chains, degree of entanglement, and corresponding characterization technique and theory therein. While cooling from melt to glass state, extra thermal stress alters the confinement of polymers vitrificated in nanopores or on thin films. Unexpected fast segmental mobility appeared on free surface of polymers while retarded on interface with strong interaction. In this review, we reviewed the current progress on dynamics and rheology behavior of confined polymers, wishing to providing some insight to advanced manufactures, such as microchip, microdevice.关键词：Confinement;Polymer dynamics;Glass transition;Rheology840|2526|0更新时间：2025-01-23
- 摘要：Hydrogels, as a class of three-dimensional polymer network containing large amount of water, exhibit characteristics similar to soft biotissues, affording them with broad applications in biomedical and engineering fields. In recent years, scientists have developed various tough hydrogels with excellent mechanical properties by incorporating physical associations such as ionic bonds, hydrogen bonds, etc. The macroscopic properties of these hydrogels are closely related to the dynamics of physical bonds and their associations. The combination of mechanical test and rheological analysis has become a powerful approach to investigate the toughening mechanism and to reveal the structure-property relationship of hydrogels. This review focuses on the dynamic feature of physical bonds and their influences on mechanical and viscoelastic behaviors of the hydrogels, by summarizing recent advances in this field. First, we introduce the relaxation behavior of physical bonds in ideal polymer networks and discuss the application of sticky-reptation model in describing the viscoelastic behavior of hydrogels with physical associations. Next, we explore how physical bonds affect the macroscopic properties of tough hydrogels, and employ physical network models to correlate their microstructures and macroscopic performances. Additionally, we consider other factors that impact the mechanical and viscoelastic behaviors of hydrogels, as well as strategies for modulating their properties of gels with physical bonds. Finally, we provide an outlook on the challenges and opportunities facing the development of hydrogels in this field.关键词：Hydrogels;Physical interactions;Mechanical properties;Toughening mechanisms;Viscoelastic behaviors670|833|0更新时间：2025-01-23
- 摘要：Cycloolefin polymers (COPs) and cycloolefin copolymers (COCs) are synthesized from norbornene derivatives using two respective methods: ring-opening metathesis polymerization followed by hydrogenation, and addition copolymerization with ethylene monomers. Recognized for their excellent performance, COPs and COCs have become the important materials in the global medical packaging and optical product sectors in recent years. A comparison of the temperature dependence of rheological properties reveals that COPs exhibit a higher melt viscosity than COCs. The Arrhenius equation analysis indicates that the optical-grade COP sample F52R has a notably higher flow activation energy compared to other samples. By the time-temperature superposition principle, master curves for each sample were constructed, yielding the entanglement modulus (GNo). The entanglement molecular weight (Me) is further determined with the TMA results for each sample. It was found that COCs’ Me can reach 16–18 kDa, which is approximately 3–4 times that of COPs’. These findings are expected to guide the selection of processing parameter in the COP and COC industries, and provide new insights in the intrinsic property differences between COPs and COCs.关键词：Cyclic olefin polymer;Cyclic olefin copolymer;Rheological property;Flow activation energy;Entanglement molecular weight882|1197|0更新时间：2025-01-23
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