软物质力学:行为特性、理论模型和测试方法

软物质已成为物理学、化学、材料、力学和生命科学重要的前沿研究课题,在技术和生产上有广阔的应用前景,是国际上普遍重视的多学科交叉研究领域,更是通向研究生命体系的桥梁。软物质力学是力学的一个新兴方向,其研究对推动多学科的交集协同发展有着极其重要的作用。然而,软物质组成复杂,常是多相集合体,且往往涉及与硬物质的界面相互作用,其运动和变化规律与一般流体和固体迥异。软物质中结构单元之间的作用力弱,在一般流体和固体中作用较小的力,如表、界面作用力、范德华力等,可能在软物质中起到主导作用,传统的流体/固体理论已无法全面刻画软物质所呈现的许多独特现象。软物质的本构关系比较复杂,涉及到流变、大变形、熵等新概念。目前,除了软物质物理、化学、生物等相关研究以外,研究者们开始从力学的角度对软物质的行为特性及其理论分析模型与测试方法进行深入探索,在生物力学、界面和接触力学、胶体力学、实验力学等领域取得了丰硕的成果。近几年来,学者们对生物组织、细胞和生物大分子、水凝胶、形状记忆聚合物、活性软材料、柔性电子器件、颗粒、液晶等多种软物质体系进行了力学分析、模拟及实验,探索了软物质微结构形成的物理机制和动力学引起的新生长规律。也有学者将软物质的不稳定性和自组装行为用于开发低成本、高性能的新材料和新设备。还有许多学者考虑学科交叉,从新的角度研究软物质材料,将连续介质力学中的本构关系、计算技术和建模方法引入到软物质模拟计算中,实现对软物质的自组装行为及表面不稳定性的理论分析,并将综合的力学测试方法和技术带入到软物质力学实验中,实现对软物质复杂力学响应的小尺度性能测试。本文论述了软物质材料的力学行为及特性:包括复杂力学响应、自组织行为和表面不稳定性及其相关研究进展;重点讨论了软物质在生物力学、界面和接触力学、胶体力学和实验力学等力学领域的研究发展;对软物质力学的发展前景做了展望,提出了值得进一步研究的方向,以期推动国内软物质力学学科的发展。     

State‐of‐the‐Art Analytical Methods for Assessing Dynamic Bonding Soft Matter Materials

Dynamic bonding materials are of high interest in a variety of fields in material science. The reversible nature of certain reaction classes is frequently employed for introducing key material properties such as the capability to self‐heal. In addition to the synthetic effort required for designing such materials, their analysis is a highly complex—yet important—endeavor. Herein, we critically review the current state of the art analytical methods and their application in the context of reversible bonding on demand soft matter material characterization for an in‐depth performance assessment. The main analytical focus lies on the characterization at the molecular level.     

Liquid-Phase Electron Microscopy for Soft Matter Science and Biology

Innovations in liquid-phase electron microscopy (LP-EM) have made it possible to perform experiments at the optimized conditions needed to examine soft matter. The main obstacle is conducting experiments in such a way that electron beam radiation can be used to obtain answers for scientific questions without changing the structure and (bio)chemical processes in the sample due to the influence of the radiation. By overcoming these experimental difficulties at least partially, LP-EM has evolved into a new microscopy method with nanometer spatial resolution and sub-second temporal resolution for analysis of soft matter in materials science and biology. Both experimental design and applications of LP-EM for soft matter materials science and biological research are reviewed, and a perspective of possible future directions is given.     

Solvated Graphenes: An Emerging Class of Functional Soft Materials

From a materials science point of view, graphene is essentially a polymer having a giant, two‐dimensional molecular configuration. In this Progress Report, solvated graphene and its derivatives are illustrated from the perspective of soft matter. Firstly, the key appealing features of graphene as a molecular building block for assembling bulk soft materials are highlighed. It is then demonstrated how the intersheet interactions in solution are correlated with the molecular structure of graphene, and how a combination of the unique molecular structure and colloidal interactions can lead to simple, solution‐phase approaches for assembling graphenes into a variety of macroscopic nanoarchitectures. A number of new exciting functions and applications are also highlighted, which are enabled by the solvation effect and in particular, it is discussed why and how solvated graphenes can offer exciting functions that are unattainable with the dried, hard counterpart. The discussion is concluded with some personal perspectives on the future directions in which this emerging class of functional soft materials could be pursued.     

热物理性质测试技术研究现状和发展趋势

本文在对热物理性质研究在热能工程、材料科学、信息科学、航天工程、环境工程、生物科学、微电子技术和计量学等众多科技领域中的重要性进行探讨的基础上，评述了热物理性质测试技术的研究现状和发展趋势。鉴于薄膜材料在微电子器件、集成电路和微电子机械系统等领域中日益广泛的应用，本文还综述了亚微米－纳米尺度薄膜材料热导率和热扩散率的测试新技术。     

涂层纳米功能材料

纳米材料复合涂层的结构和特性是纳米科技中的重要研究课题,本文重点讨论了制造技术的新观念,纳米材料的完美定律,涂层材料的发展前景,纳米场发射特性等.进而,讨论重要的物理理论研究的热点-电子强关联体系和软凝聚态问题.展现了涂层材料科学与技术的深刻理论内容和重要的发展前景.     

Computational physics: a perspective

Computing comprises three distinct strands: hardware, software and the ways they are used in real or imagined worlds. Its use in research is more than writing or running code. Having something significant to compute and deploying judgement in what is attempted and achieved are especially challenging. In science or engineering, one must define a central problem in computable form, run such software as is appropriate and, last but by no means least, convince others that the results are both valid and useful. These several strands are highly interdependent. A major scientific development can transform disparate aspects of information and computer technologies. Computers affect the way we do science, as well as changing our personal worlds. Access to information is being transformed, with consequences beyond research or even science. Creativity in research is usually considered uniquely human, with inspiration a central factor. Scientific and technological needs are major forces in innovation, and these include hardware and software opportunities. One can try to define the scientific needs for established technologies (atomic energy, the early semiconductor industry), for rapidly developing technologies (advanced materials, microelectronics) and for emerging technologies (nanotechnology, novel information technologies). Did these needs define new computing, or was science diverted into applications of then-available codes? Regarding credibility, why is it that engineers accept computer realizations when designing engineered structures, whereas predictive modelling of materials has yet to achieve industrial confidence outside very special cases? The tensions between computing and traditional science are complex, unpredictable and potentially powerful.     

Programming the shape-shifting of flat soft matter

Shape-shifting of flat materials into the desired 3D configuration is an alternative design route for fabrication of complex 3D shapes, which provides many benefits such as access to the flat material surface and the ability to produce well-described motions. The advanced production techniques that primarily work in 2D could then be used to add complex surface features to the flat material. The combination of complex 3D shapes and surface-related functionalities has a wide range of applications in biotechnology, actuators/sensors, and engineering of complex metamaterials. Here, we categorize the different programming strategies that could be used for planning the shape-shifting of soft matter based on the type of stresses generated inside the flat material and present an overview of the ways those mechanisms could be used to achieve the desired 3D shapes. Stress gradients through the thickness of the material, which generate out-of-plane bending moments, and compressive in-plane stresses that result in out-of-plane buckling constitute the major mechanisms through which shape-shifting of the flat matter could be programmed. We review both programming strategies with a focus on the underlying physical principles, which are highly scalable and could be applied to other structures and materials. The techniques used for programming the time sequence of shape-shifting are discussed as well. Such types of so-called “sequential” shape-shifting enable achieving more complex 3D shapes, as the kinematics of the movements could be planned in time to avoid collisions. Ultimately, we discuss what 3D shapes could be achieved through shape-shifting from flat soft matter and identify multiple areas of application.     

Photoprogrammable Mesogenic Soft Helical Architectures: A Promising Avenue toward Future Chiro-Optics

Mesogenic soft materials, having single or multiple mesogen moieties per molecule, commonly exhibit typical self-organization characteristics, which promotes the formation of elegant helical superstructures or supramolecular assemblies in chiral environments. Such helical superstructures play key roles in the propagation of circularly polarized light and display optical properties with prominent handedness, that is, chiro-optical properties. The leveraging of light to program the chiro-optical properties of such mesogenic helical soft materials by homogeneously dispersing photosensitive chiral material into an achiral soft system or covalently connecting photochromic moieties to the molecules has attracted considerable attention in terms of materials, properties, and potential applications and has been a thriving topic in both fundamental science and application engineering. State-of-the-art technologies are described in terms of the material design, synthesis, properties, and modulation of photoprogrammable chiro-optical mesogenic soft helical architectures. Additionally, the scientific issues and technical problems that hinder further development of these materials for use in various fields are outlined and discussed. Such photoprogrammable mesogenic soft helical materials are competitive candidates for use in stimulus-controllable chiro-optical devices with high optical efficiency, stable optical properties, and easy miniaturization, facilitating the future integration and systemization of chiro-optical chips in photonics, photochemistry, biomedical engineering, chemical engineering, and beyond.     

Advanced Soft Materials,Sensor Integrations,and Applications of Wearable Flexible Hybrid Electronics in Healthcare,Energy, and Environment

Recent advances in soft materials and system integration technologies have provided a unique opportunity to design various types of wearable flexible hybrid electronics (WFHE) for advanced human healthcare and human–machine interfaces. The hybrid integration of soft and biocompatible materials with miniaturized wireless wearable systems is undoubtedly an attractive prospect in the sense that the successful device performance requires high degrees of mechanical flexibility, sensing capability, and user-friendly simplicity. Here, the most up-to-date materials, sensors, and system-packaging technologies to develop advanced WFHE are provided. Details of mechanical, electrical, physicochemical, and biocompatible properties are discussed with integrated sensor applications in healthcare, energy, and environment. In addition, limitations of the current materials are discussed, as well as key challenges and the future direction of WFHE. Collectively, an all-inclusive review of the newly developed WFHE along with a summary of imperative requirements of material properties, sensor capabilities, electronics performance, and skin integrations is provided.     

A Technical Introduction to Transmission Electron Microscopy for Soft‐Matter: Imaging,Possibilities, Choices,and Technical Developments

With a significant role in material sciences, physics, (soft matter) chemistry, and biology, the transmission electron microscope is one of the most widely applied structural analysis tool to date. It has the power to visualize almost everything from the micrometer to the angstrom scale. Technical developments keep opening doors to new fields of research by improving aspects such as sample preservation, detector performance, computational power, and workflow automation. For more than half a century, and continuing into the future, electron microscopy has been, and is, a cornerstone methodology in science. Herein, the technical considerations of imaging with electrons in terms of optics, technology, samples and processing, and targeted soft materials are summarized. Furthermore, recent advances and their potential for application to soft matter chemistry are highlighted.     

Soft Robotic Grippers

Advances in soft robotics, materials science, and stretchable electronics have enabled rapid progress in soft grippers. Here, a critical overview of soft robotic grippers is presented, covering different material sets, physical principles, and device architectures. Soft gripping can be categorized into three technologies, enabling grasping by: a) actuation, b) controlled stiffness, and c) controlled adhesion. A comprehensive review of each type is presented. Compared to rigid grippers, end‐effectors fabricated from flexible and soft components can often grasp or manipulate a larger variety of objects. Such grippers are an example of morphological computation, where control complexity is greatly reduced by material softness and mechanical compliance. Advanced materials and soft components, in particular silicone elastomers, shape memory materials, and active polymers and gels, are increasingly investigated for the design of lighter, simpler, and more universal grippers, using the inherent functionality of the materials. Embedding stretchable distributed sensors in or on soft grippers greatly enhances the ways in which the grippers interact with objects. Challenges for soft grippers include miniaturization, robustness, speed, integration of sensing, and control. Improved materials, processing methods, and sensing play an important role in future research.     

Nanobiomaterials and Nanoanalysis: Opportunities for Improving the Science to Benefit Biomedical Technologies

Nanomaterials advocated for biomedical applications must exhibit well‐controlled surface properties to achieve optimum performance in complex biological or physiological fluids. Dispersed materials with extremely high specific surface areas require as extensive characterization as their macroscale biomaterials analogues. However, current literature is replete with many examples of nanophase materials, most notably nanoparticles, with little emphasis placed on reporting rigorous surface analysis or characterization, or in formal implementation of surface property standards needed to validate structure‐property relationships for biomedical applications. Correlations of nanophase surface properties with their stability, toxicity and biodistributions are essential for in vivo applications. Surface contamination is likely, given their processing conditions and interfacial energies. Leaching adventitious adsorbates from high surface area nanomaterials is a possible toxicity mechanism. Polydimethylsiloxane (PDMS), long known as a ubiquitous contaminant in clean room conditions, chemical synthesis and microfabrication, remains a likely culprit in nanosystems fabrication, especially in synthesis, soft lithography and contact molding methods. New standards and expectations for analyzing the interfacial properties of nanoparticles and nano‐fabricated technologies are required. Surface science analytical rigor similar to that applied to biomedical devices, nanophases in microelectronics and heterogeneous catalysts should serve as a model for nanomaterials characterization in biomedical technologies.     

Emerging Functionality in Transition-Metal Compounds Driven by Broken Symmetry, Reduced Dimensionality, or Spatial Confinement

2008年10月23—27日，“2008第七届中国纳米科技（武汉）研讨会”在湖北大学隆重召开。Prof.Robert Snyder （Georgia Institute of Technology）, Prof. Ward Plummer （Oak Ridge National Laboratory and University of Tennessee） , Prof. M.P. Pileni （University of Marie and Curie, France）, Prof. Zhong Lin.Wang （Georgia Institute of Technology, USA）和薛其坤院士（Tsinghua University）、赵东元院士（Fudan University）、李亚栋教授（Tsinghua University）等出席大会并做特邀主题报告。本期摘要介绍美国科学院院士E．Ward Plummer的报告：     

25th Anniversary Article: Reversible and Adaptive Functional Supramolecular Materials: “Noncovalent Interaction” Matters

Supramolecular materials held together by noncovalent interactions, such as hydrogen bonding, host–guest interactions, and electrostatic interactions, have great potential in material science. The unique reversibility and adaptivity of noncovalent intreractions have brought about fascinating new functions that are not available by their covalent counterparts and have greatly enriched the realm of functional materials. This review article aims to highlight the very recent and important progresses in the area of functional supramoleuclar materials, focusing on adaptive mechanical materials, smart sensors with enhanced selectivity, soft luminescent and electronic nanomaterials, and biomimetic and biomedical materials with tailored structures and functions. We cannot write a complete account of all the interesting work in this area in one article, but we hope that it can in a way reflect the current situation and future trends in this prosperously developing area of functional supramolecular materials.     

Formation of Network and Cellular Structures by Viscoelastic Phase Separation

Network (sponge) and cellular structures are often seen in various types of materials. Materials with such structures are generally characterized by light weight and high mechanical strength. The usefulness of such materials is highlighted, for example, by the remarkable material properties of bone tissue, which often has a highly porous structure. In artificial materials, plastic and metallic foams and breads have such structures. Here, we describe a physical principle for producing network and cellular structures using phase separation, and its potential applications to the morphological control of materials spanning from soft to hard matter.     

Bioinspired 2D Nanomaterials for Sustainable Applications

The increasing demand for constructing ecological civilization and promoting socially sustainable development has encouraged scientists to develop bioinspired materials with required properties and functions. By bringing science and nature together, plenty of novel materials with extraordinary properties can be created by learning the best from natural species. In combination with the exceptional features of 2D nanomaterials, bioinspired 2D nanomaterials and technologies have delivered significant achievements. Here, the progress over the past decade in bioinspired 2D photonic structures, energy nanomaterials, and superwetting materials, is summarized, together with the challenges and opportunities in developing bioinspired materials for sustainable energy and environmental technologies.     

Design of untethered soft material micromachine for life-like locomotion

Living organisms composed of composite materials with complex structures support autonomous and intelligent behaviors, such as motility, perception and response to changes of the environment. By studying the biological structures and their environmental interactions, researchers are now using these natural systems as models for building soft material machines. In this review, we discuss materials and machine engineering principles to achieve life-like locomotion and functionalities in untethered soft micromachines. Through the various mechanochemical or physical mechanisms, we show how molecular motion can be collectively amplified into versatile macroscopic deformation by materials engineering across multiple length scales. In controlled ways, mobile micromachines are made to crawl, roll or jump and adaptive to various terrains, typically inspired by the terrestrial animals while propulsion of swimming micromachines are guided by aquatic organisms. Besides, out-of-equilibrium behaviors of living systems, such as cell cycling, have stimulated the design of autonomous movement. Furthermore, we review the recent efforts on robotic locomotion intelligence to achieve adaptive, functional locomotion and navigation in complex environment. We finally provide a critical perspective for the field of soft micromachines, and highlight the key challenges of different material systems that need to be overcome to realize practical use.     

Synergetic Behavior in 2D Layered Material/Complex Oxide Heterostructures

The marriage between a 2D layered material (2DLM) and a complex transition metal oxide (TMO) results in a variety of physical and chemical phenomena that cannot be achieved in either material alone. Interesting recent discoveries in systems such as graphene/SrTiO₃, graphene/LaAlO₃/SrTiO₃, graphene/ferroelectric oxide, MoS₂/SrTiO₃, and FeSe/SrTiO₃ heterostructures include voltage scaling in field‐effect transistors, charge state coupling across an interface, quantum conductance probing of the electrochemical activity, novel memory functions based on charge traps, and greatly enhanced superconductivity. In this context, various properties and functionalities appearing in numerous different 2DLM/TMO heterostructure systems are reviewed. The results imply that the multidimensional heterostructure approach based on the disparate material systems leads to an entirely new platform for the study of condensed matter physics and materials science. The heterostructures are also highly relevant technologically as each constituent material is a promising candidate for next‐generation optoelectronic devices.