Soft Condensed Matter
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Showing new listings for Thursday, 25 September 2025
- [1] arXiv:2509.19496 [cn-pdf, pdf, other]
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Title: Reaction/Diffusion Competition Drives Anomalous Relaxation of VitrimersTitle: 反应/扩散竞争驱动动态玻璃的异常弛豫Subjects: Soft Condensed Matter (cond-mat.soft) ; Materials Science (cond-mat.mtrl-sci)
Vitrimers are an emerging class of crosslinked polymer networks in which dynamic covalent bonds can exchange and rearrange, without any significant change in population of bonded states.1 Because these bonds can rearrange at high temperatures without disintegration of the network, vitrimers could combine the mechanical stability of traditional permanently crosslinked networks with the recyclability of glasses and physical networks. However, unlike classical transient/physical networks, vitrimers can relax at a rate that is decoupled from the mobility of their polymer segments. This challenges our fundamental understanding of how dynamic covalent networks relax and deform. Here we combine simulations, theory, and experiments to show that vitrimer dynamics exhibit two very different regimes: (i) a high temperature regime controlled by the local bond-exchange reaction rate and (ii) a low temperature regime controlled by segmental diffusion. This fundamental difference from traditional physical networks explains why vitrimers can exhibit Arrhenius dynamics, providing a foundation for their rational design.
动态共价键网络中，可交换和重新排列的动态共价键在结合态的种群没有显著变化的情况下。1 由于这些键可以在高温下重新排列而不会破坏网络结构，因此Vitrimers可以将传统永久交联网络的机械稳定性与玻璃和物理网络的可回收性相结合。 然而，与经典的瞬时/物理网络不同，Vitrimers的松弛速率与其聚合物链段的流动性是解耦的。 这挑战了我们对动态共价网络如何松弛和变形的基本理解。 在这里，我们结合模拟、理论和实验来表明，Vitrimers动力学表现出两个非常不同的区域：(i) 由局部键交换反应速率控制的高温区域和(ii) 由链段扩散控制的低温区域。 这种与传统物理网络的根本差异解释了为什么Vitrimers可以表现出阿伦尼乌斯动力学，为它们的合理设计提供了基础。
- [2] arXiv:2509.19560 [cn-pdf, pdf, html, other]
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Title: Conservative yet constitutively odd elasticity in prestressed metamaterialsTitle: 预应力超材料中的保守但构成性奇异弹性Comments: 5 pages, 2 figuresSubjects: Soft Condensed Matter (cond-mat.soft)
We introduce a design principle for mechanical metamaterials based on "odd elasticity, once removed." By revisiting classic results relating the variation of Cauchy stress and Lagrangian strain around a prestressed reference state, we show how anisotropic, equilibrium prestress can generate a major anti-symmetry in the material's constitutive response. Tuning the system to such a state drives it to a critical instability, radically transforming its acoustic properties. We then inverse-design several uniform 2D solids that act as unique waveguides supporting decoupled modes along special lattice directions: a string-like mode and an exotic, in-plane soft mode with a flexural character ($\omega \sim q^2$). The soft modes are insensitive to the value of the anisotropic prestress and exhibit oscillating momentum density but support a non-oscillatory, constant energy current. This principle of harnessing conservative "oddness" to unlock instability-driven wave phenomena provides a powerful new route to creating tunable materials for filtering, guiding, and controlling mechanical waves.
我们引入了一种基于“奇弹性，一次移除”的机械超材料设计原理。 通过重新审视关于预应力参考状态下柯西应力和拉格朗日应变变化的经典结果，我们展示了各向异性平衡预应力如何在材料的本构响应中产生显著的反对称性。 将系统调整到这种状态会引发临界失稳，彻底改变其声学特性。 随后，我们逆向设计了几种均匀的二维固体，它们作为独特的波导，支持沿特殊晶格方向的解耦模式：一种类似弦的模式和一种具有弯曲特性的奇异面内软模（$\omega \sim q^2$）。 软模对各向异性预应力的值不敏感，并表现出振荡动量密度，但支持非振荡的恒定能量电流。 利用保守“奇性”来解锁由失稳驱动的波现象这一原理，为创建可调材料以过滤、引导和控制机械波提供了一条强大的新途径。
- [3] arXiv:2509.19942 [cn-pdf, pdf, other]
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Title: Smart copolymer microgels with high volume phase transition temperature: Composition, swelling, and morphologyTitle: 具有高体积相变温度的智能共聚物微凝胶：组成、溶胀和形态Aditi Gujare, Stefanie Uredat, Jonas Runge, Felix Morgenstern, Domenico Truzzolillo, Thomas Hellweg, Julian OberdisseComments: 24 pages, 9 figuresSubjects: Soft Condensed Matter (cond-mat.soft)
The thermosensitivity and microstructure of microgels made by copolymerizing standard microgel-forming monomers with more hydrophilic comonomers is investigated, with the aim of increasing the volume phase transition temperature (VPTT). We precisely determine the incorporation of N-(hydroxymethyl)acrylamide (HMAM) and purpose-synthesized N-(2-hydroxyisopropyl)acrylamide (HIPAM) into microgels -- neither of which forms microgels on its own by precipitation polymerization. The swelling properties and microstructure of the resulting copolymer microgels with N-isopropylacrylamide (NIPAM, LCST ca. 32{\deg}C) and N-isopropylmethacrylamide (NIPMAM, LCST ca. 44{\deg}C) are then characterized via turbidimetry, DLS, and AFM. At low comonomer contents, all microgel particles exhibit moderate growth in size. Beyond a system-specific threshold, we observe a significant jump in size, and smoother swelling behavior. For NIPAM-HIPAM, the size increase is linked to a strong rise in swelling capacity, and the formation of a thick corona. The effect of the hydrophilic comonomers on the VPTT correlates linearly with their true composition, allowing us to extrapolate the VPTT of hypothetical pure HMAM and HIPAM microgels. This leads to 99{\deg}C for HMAM, and 68{\deg}C for HIPAM for the respective VPTT. These numbers can be seen as useful indicators of the effect of these monomers on the VPTT in the copolymerized microgels. The observed changes in VPTT, swelling, size, and morphology suggest that high-VPTT microgels possess unique internal molecular composition gradients, likely due to hydrophobic interactions during synthesis. Our results have potential implications for developing temperature-sensitive microgel-based membranes that can self-adapt their permeability at higher operating temperatures in energy applications.
热敏感性和由标准微凝胶形成单体与更亲水的共聚单体共聚制成的微凝胶的微观结构被研究，目的是提高体积相变温度（VPTT）。我们精确确定了N-(羟甲基)丙烯酰胺（HMAM）和专门合成的N-(2-羟基异丙基)丙烯酰胺（HIPAM）在微凝胶中的掺入量——这两种单体本身通过沉淀聚合都不能形成微凝胶。然后通过浊度法、DLS和AFM表征了含有N-异丙基丙烯酰胺（NIPAM，LCST约为32{\deg }C）和N-异丙基甲基丙烯酰胺（NIPMAM，LCST约为44{\deg }C）的所得共聚物微凝胶的溶胀性能和微观结构。在低共聚单体含量下，所有微凝胶粒子表现出适度的尺寸增长。超过系统特定的阈值后，我们观察到尺寸显著增加以及更平滑的溶胀行为。对于NIPAM-HIPAM，尺寸增加与溶胀能力的强烈上升以及厚层冠的形成有关。亲水性共聚单体对VPTT的影响与其真实组成呈线性相关，使我们能够推断出假设纯HMAM和HIPAM微凝胶的VPTT。这导致HMAM的VPTT为99{\deg }C，而HIPAM的VPTT为68{\deg }C。这些数值可以作为这些单体在共聚微凝胶中对VPTT影响的有用指标。观察到的VPTT、溶胀、尺寸和形态的变化表明，高VPTT微凝胶具有独特的内部分子组成梯度，可能是由于合成过程中的疏水相互作用。我们的结果在开发可在较高操作温度下自我适应渗透性的温度敏感微凝胶基膜方面具有潜在的应用意义，在能源应用中可能有重要影响。
- [4] arXiv:2509.19971 [cn-pdf, pdf, other]
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Title: Dynamic self-assembly of active particle systems controlled by light fieldsTitle: 活性粒子系统的动态自组装受光场控制Subjects: Soft Condensed Matter (cond-mat.soft)
Active particle systems are a class of non-equilibrium systems composed of self-propelled Brownian particles; through interactions between particles within the system, a variety of intriguing collective behaviors can emerge. Based on Brownian dynamics simulations, this study investigates the formation and transition mechanisms of ordered structures in active particle systems regulated by light fields. The study reveals that, under light field regulation, active particles undergo large-scale phase separation behavior, forming specific ordered structures and enabling the dynamic transition between multiple ordered structures. This study systematically explores the effects of light fields on this dynamic phase transition and the corresponding regulatory mechanisms. The research findings provide important references for the precise regulation of collective structures in active systems and the fabrication of micro-nano intelligent devices.
活性粒子系统是一类由自推进布朗粒子组成的非平衡系统；通过系统内粒子之间的相互作用，可以出现各种引人入胜的集体行为。 基于布朗动力学模拟，本研究探讨了光场调控下活性粒子系统中有序结构的形成和转变机制。 研究表明，在光场调控下，活性粒子会发生大规模相分离行为，形成特定的有序结构，并实现多种有序结构之间的动态转换。 本研究系统地探讨了光场对这种动态相变及其相应调控机制的影响。 研究成果为活性系统中集体结构的精确调控以及微纳米智能器件的制造提供了重要参考。
- [5] arXiv:2509.20005 [cn-pdf, pdf, html, other]
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Title: Living Droplets with Mesoscale SwimmersTitle: 具有介观游动体的液滴Subjects: Soft Condensed Matter (cond-mat.soft) ; Biological Physics (physics.bio-ph)
We study the activity of "living" droplets, which confine 1-6 mesoswimmers in 3D using a superhydrophobic substrate. The swimmers induce oscillations of the droplets at their inherent resonant frequencies, regardless of swimmer size and number. In contrast, the droplet oscillation amplitude is strongly affected by crowding, which we successfully model with a new scaling law and show that crowding reduces the speed of the swimmers. These fundamental living matter physics results reveal mechanisms for bio-inspired droplet actuation with implications for mesoscale robotics, fluidics, and sensing.
我们研究了"活"液滴的活性，这些液滴通过超疏水基底在3D中限制1-6个介观游泳者。 无论游泳者的大小和数量如何，游泳者都会在其固有共振频率下引发液滴的振荡。 相反，液滴的振荡幅度受到拥挤的显著影响，我们成功地用一个新的标度定律对其进行建模，并表明拥挤会降低游泳者的速度。 这些基本的活物质物理结果揭示了生物启发液滴驱动的机制，对介尺度机器人技术、流体学和传感具有重要意义。
- [6] arXiv:2509.20066 [cn-pdf, pdf, html, other]
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Title: Glassy dynamics in two-dimensional ring polymers: size versus stiffness polydispersityTitle: 二维环状聚合物中的玻璃态动力学：尺寸与刚性多分散性Comments: 12 pages, 7 figuresSubjects: Soft Condensed Matter (cond-mat.soft)
Soft glassy materials often consist of deformable objects. Here, we use a two-dimensional assembly of semi-flexible ring polymers as a model system to investigate how polydispersity in particle stiffness or size influences the onset of glassy dynamics. In simulations at fixed polydispersity 30%, we find that stiffness dispersity drives most rings into elongated conformations at high densities, leading to orientationally ordered structures that cause dynamical slowing down. In contrast, size dispersity generates a bimodal population: small rings remain circular and act as rigid inclusions, while large rings elongate, producing frustration that delays arrest. Real-space maps of bond relaxation reveal strikingly different pathways of dynamical heterogeneity, with long-lived domains persisting under stiffness dispersity but rapidly percolating relaxation under size dispersity. Moreover, local correlations between ring shape, orientational order, and mobility show that stiffness dispersity produces dynamics that are strongly structure-sensitive, whereas size dispersity activates motion from both circular and elongated populations. By linking microscopic deformability to emergent glassy dynamics, this study identifies how the nature of polydispersity controls the relaxation pathways of soft glasses.
软玻璃材料通常由可变形物体组成。 在这里，我们使用二维半柔性环形聚合物的集合作为模型系统，以研究粒子刚度或尺寸的多分散性如何影响玻璃动力学的开始。 在固定多分散性30%的模拟中，我们发现刚度多分散性使大多数环在高密度下进入伸长构象，导致取向有序结构，从而引起动力学减缓。 相反，尺寸多分散性产生双峰种群：小环保持圆形并作为刚性内含物，而大环伸长，产生阻碍，延迟冻结。 键松弛的真实空间图显示了明显不同的动力学异质性路径，在刚度多分散性下存在持久的区域，而在尺寸多分散性下松弛迅速渗透。 此外，环形状、取向秩序和移动性之间的局部相关性表明，刚度多分散性产生对结构高度敏感的动力学，而尺寸多分散性则从圆形和伸长种群中激活运动。 通过将微观可变形性与出现的玻璃动力学联系起来，这项研究确定了多分散性的性质如何控制软玻璃的弛豫路径。
- [7] arXiv:2509.20110 [cn-pdf, pdf, html, other]
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Title: Quantitative description of the surface tension minimum in a two-component surfactant systemTitle: 两组分表面活性剂体系中表面张力最小值的定量描述Comments: 34 page, 10 figures; submitted for publication in LangmuirSubjects: Soft Condensed Matter (cond-mat.soft) ; Statistical Mechanics (cond-mat.stat-mech)
The Gibbs adsorption equation is the thermodynamic cornerstone for the description and understanding of the surface tension in a surfactant solution. It relates the decrease in surface tension to an increased surfactant adsorption. In the early 1940's, it therefore puzzled researchers to sometimes observe a minimum in the surface tension for certain surfactant solutions, which seemed to indicate surfactant desorption (even depletion) according to the Gibbs adsorption equation. It is now understood that the minimum is related to contamination of the surfactant (notably by dodecanol) and its occurrence has since then been studied extensively in experiments. Still, the precise role of the (tiny amount of) contaminant present is not well understood and a quantitative description and understanding of the minimum in the experimental surface tension is lacking. It is the aim of the present article to provide such a quantitative description. Our theoretical analysis is based on a Statistical Thermodynamic treatment of the Langmuir model for a surfactant mixture combined with the mass action model adapted to describe the formation of mixed micelles. A new Statistical Thermodynamic expression for the surface tension is derived and used to compare with a number of surface tension experiments for both ionic and non-ionic surfactant systems.
吉布斯吸附方程是描述和理解表面活性剂溶液表面张力的热力学基础。 它将表面张力的降低与表面活性剂吸附的增加联系起来。 在20世纪40年代初，研究人员有时会观察到某些表面活性剂溶液的表面张力出现最小值，这似乎根据吉布斯吸附方程表明了表面活性剂的解吸（甚至耗尽）。 现在人们知道，这个最小值与表面活性剂的污染有关（特别是由十二醇引起的污染），自那时以来，其出现已在实验中被广泛研究。 尽管如此，所存在的（少量的）污染物的确切作用仍未被充分理解，对实验中表面张力最小值的定量描述和理解仍然缺乏。 本文的目的是提供这样的定量描述。 我们的理论分析基于一种统计热力学处理方法，该方法适用于表面活性剂混合物的朗缪尔模型，并结合了适用于描述混合胶束形成的质量作用模型。 推导出了一种新的表面张力的统计热力学表达式，并用于与多种离子型和非离子型表面活性剂体系的表面张力实验进行比较。
- [8] arXiv:2509.20130 [cn-pdf, pdf, html, other]
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Title: Lateral disorder in Langmuir monolayers: theoretical derivations and grazing-incidence X-ray diffractionTitle: 液膜单层中的侧向无序：理论推导和掠入射X射线衍射Comments: This is an original manuscript consisting of 15 pages and 7 figures. To be submitted for publication in the (IUCr) Journal of Applied CrystallographySubjects: Soft Condensed Matter (cond-mat.soft) ; Disordered Systems and Neural Networks (cond-mat.dis-nn) ; Computational Physics (physics.comp-ph)
Recent studies of the self-assembly of Langmuir monolayers have revealed novel forms of lateral molecular ordering. Such studies typically involve the use of grazing-incidence synchrotron radiation scattering, and the lateral order manifests itself as distinct diffraction patterns. The more intricate the molecular organization, the more complicated the corresponding diffraction pattern is. To the point where standard analysis, i.e., identifying peak positions and solving the crystal structure, is insufficient to describe the system. In such cases, a physics-based simulation of the diffraction is required. In this article, we present a versatile theoretical framework for simulating complex structural molecular ordering in Langmuir monolayers. We begin by applying the formalism to a simple case of solid-state monolayers and extend the analysis to describe the structural organization in the collapsed state. The applicability of the method is validated through comparison with experimental data collected at the bending magnet synchrotron beamline.
最近对Langmuir单层自组装的研究揭示了横向分子有序的新形式。 此类研究通常涉及掠入射同步辐射散射的使用，横向有序表现为不同的衍射图案。 分子组织越复杂，相应的衍射图案就越复杂。 到了标准分析（即确定峰位和解决晶体结构）不足以描述该系统的情况。 在这些情况下，需要进行基于物理的衍射模拟。 在本文中，我们提出了一种通用的理论框架，用于模拟Langmuir单层中的复杂结构分子有序。 我们首先将该形式化方法应用于固态单层的简单情况，并扩展分析以描述坍塌状态下的结构组织。 该方法的适用性通过与在弯铁同步辐射束线收集的实验数据进行比较得到验证。
- [9] arXiv:2509.20132 [cn-pdf, pdf, html, other]
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Title: Random close packing fraction of bidisperse discs: Theoretical derivation and exact boundsTitle: 二元分散圆盘的随机密堆积分数：理论推导与精确界限Comments: 5 pages, 5 figuresSubjects: Soft Condensed Matter (cond-mat.soft) ; Disordered Systems and Neural Networks (cond-mat.dis-nn) ; Mathematical Physics (math-ph)
A long-standing problem has been a theoretical prediction of the densest packing fraction of random packings, $\Phi_{RCP}$, of same-size discs in $d=2$ and spheres in $3$. However, to minimize order, experiments and numerical simulations often use two-size discs. For practical purposes, then, a predictive theory for the packing fraction, $\Phi_{RCP}$, of the densest such bidisperse packings is more useful. A disorder-guaranteeing theory is formulated here to fill this gap, using an approach that led to an exact solution for monodisperse discs in $d=2$ [1]. $\Phi_{RCP}$ depends on the sizes ratio, $D$, and concentrations, $p$, of the disc types and the developed theory enables derivation of exact and rigorous upper and lower bounds on $\Phi_{RCP}(p,D)$, as well as an explicit prediction of it.
一个长期存在的问题是理论预测随机堆积中相同大小的圆盘在$\Phi_{RCP}$的最大堆积分数，以及相同大小的球体在$d=2$和$3$的最大堆积分数。 然而，为了最小化有序性，实验和数值模拟通常使用两种尺寸的圆盘。 因此，对于实际应用而言，预测这种双分散堆积的最大堆积分数$\Phi_{RCP}$的理论更有用。 本文提出了一种保证无序性的理论来填补这一空白，该理论采用了一种导致单分散圆盘在$d=2$中精确解的方法 [1]。 $\Phi_{RCP}$依赖于圆盘类型尺寸比$D$和浓度$p$，并且该理论能够推导出$\Phi_{RCP}(p,D)$的精确和严格的上下界，以及对其的显式预测。
- [10] arXiv:2509.20313 [cn-pdf, pdf, html, other]
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Title: Anisotropic shrinkage and finite strains in confined frictional contactsTitle: 各向异性收缩和受限摩擦接触中的有限应变Subjects: Soft Condensed Matter (cond-mat.soft)
We report on an experimental investigation of the interplay between friction, adhesion, contact geometry, and finite strains for smooth frictional contacts between rigid spherical glass probes and flat silicone substrates. Using both bulk and layer substrates under various loading conditions (normal force, radius of the probe), we show that shear-induced anisotropic shrinkage of the adhesive contact area under steady-state sliding is an effect of finite-elasticity conditions and is drastically affected by the level of geometric confinement. The resulting non-linear coupling between the normal and lateral directions is also investigated measuring the changes in the indentation depth (conv. normal load) during the stiction of the adhesive contacts under imposed normal load (conv. indentation depth) conditions, with strong effects of contact confinement. From a comparison with adhesiveless linear contact mechanics calculations, we show that the experimental observations can only be accounted for by the occurrence of finite strains/displacements conditions. Accordingly, measurements of the in-plane surface displacements at the surface of the rubber substrates confirm that strain levels well in the neo-Hookean range are experienced during steady-state frictional sliding.
我们报告了对刚性球形玻璃探针与平坦硅胶基底之间光滑摩擦接触中摩擦、粘附、接触几何和有限应变之间相互作用的实验研究。 在不同加载条件（法向力、探针半径）下使用体基底和层基底，我们表明在稳态滑动下由剪切引起的粘附接触区域各向异性收缩是有限弹性条件的效果，并且受到几何约束水平的显著影响。 这种法向和侧向方向之间的非线性耦合也通过测量在施加法向载荷（对应于压入深度）条件下粘附接触的粘着过程中压入深度（对应于法向载荷）的变化进行研究，显示出接触约束的强烈影响。 与无粘附的线性接触力学计算相比，我们证明只有在出现有限应变/位移条件的情况下才能解释实验观察结果。 因此，对橡胶基底表面的面内表面位移的测量证实，在稳态摩擦滑动过程中经历了处于新胡克范围内的应变水平。
New submissions (showing 10 of 10 entries )
- [11] arXiv:2509.19837 (cross-list from cond-mat.stat-mech) [cn-pdf, pdf, html, other]
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Title: Gauge invariance and hyperforce correlation theory for equilibrium fluid mixturesTitle: 规范不变性与平衡流体混合物的超力关联理论Joshua Matthes, Silas Robitschko, Johanna Müller, Sophie Hermann, Florian Sammüller, Matthias SchmidtComments: 15 pages, 2 figuresSubjects: Statistical Mechanics (cond-mat.stat-mech) ; Soft Condensed Matter (cond-mat.soft)
We formulate gauge invariance for the equilibrium statistical mechanics of classical multi-component systems. Species-resolved phase space shifting constitutes a gauge transformation which we analyze using Noether's theorem and shifting differential operators that encapsulate the gauge invariance. The approach yields exact equilibrium sum rules for general mixtures. Species-resolved gauge correlation functions for the force-force and force-gradient pair correlation structure emerge on the two-body level. Exact 3g-sum rules relate these correlation functions to the spatial Hessian of the partial pair distribution functions. General observables are associated with hyperforce densities that measure the covariance of the given observable with the interparticle, external, and diffusive partial force density observables. Exact hyperforce and Lie algebra sum rules interrelate these correlation functions with each other. The practical accessibility of the framework is demonstrated for binary Lennard-Jones mixtures using both adaptive Brownian dynamics and grand canonical Monte Carlo simulations. Specifically, we investigate the force-force pair correlation structure of the Kob-Andersen bulk liquid and we show results for representative hyperforce correlation functions in Wilding et al.'s symmetrical mixture confined between two asymmetric planar parallel walls.
我们为经典多组分系统的平衡统计力学制定规范不变性。 物种分辨的相空间移动构成一个规范变换，我们使用诺特定理和包含规范不变性的移动微分算子对其进行分析。 该方法得出一般混合物的精确平衡求和规则。 在两体层面上出现物种分辨的规范相关函数，用于力-力和力梯度对相关结构。 精确的3g求和规则将这些相关函数与部分对分布函数的空间海森矩阵相关联。 一般可观测量与超力密度相关联，这些超力密度测量给定可观测量与粒子间、外部和扩散部分力密度可观测量的协方差。 精确的超力和李代数求和规则相互关联这些相关函数。 通过自适应布朗动力学和巨正则蒙特卡罗模拟，展示了该框架在二元Lennard-Jones混合物中的实际可访问性。 具体而言，我们研究了Kob-Andersen体液的力-力对相关结构，并展示了Wilding等人在两个不对称平面平行壁之间的对称混合物中代表性超力相关函数的结果。
- [12] arXiv:2509.20248 (cross-list from physics.flu-dyn) [cn-pdf, pdf, html, other]
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Title: Pressure shifts in large-amplitude pulsatile shear flow: A microfluidic method to probe the normal stress response of complex fluidsTitle: 大振幅脉动剪切流中的压力漂移：一种用于探测复杂流体法向应力响应的微流控方法Subjects: Fluid Dynamics (physics.flu-dyn) ; Soft Condensed Matter (cond-mat.soft)
A microfluidic approach to probing the first normal stress difference from single-point pressure measurements in pulsatile shear flows is presented. Using an original experimental design, we examine the near-zero-mean pulsatile flow of polymeric solutions in a straight, deformable microchannel at low Reynolds and Womersley numbers. An important aspect of this work is that the enhanced fluid elastic stresses can be efficiently determined via the pressure shift from pressure-controlled large-amplitude pulsatile shear experiments. We find a scaling law that collapses pressure-shift data from viscoelastic fluids of different molecular weights onto a single master curve that can then be used to predict this phenomenology. Taken together, these results could help shed light on our understanding of the non-linear normal stress responses in time-dependent flows.
一种通过单点压力测量来探测脉动剪切流中第一个法向应力差的微流控方法被提出。 使用一种原创的实验设计，我们在低雷诺数和沃默利数下，研究了直的可变形微通道中聚合物溶液的近零均值脉动流动。 这项工作的一个重要方面是，可以通过压力控制的大振幅脉动剪切实验中的压力偏移，有效地确定增强的流体弹性应力。 我们发现了一个标度定律，该定律可以将不同分子量的粘弹性流体的压力偏移数据归一化到一条单一的主曲线，然后可用于预测这种现象。 综合来看，这些结果可能有助于加深我们对随时间变化的流动中非线性法向应力响应的理解。
- [13] arXiv:2509.20305 (cross-list from cond-mat.stat-mech) [cn-pdf, pdf, html, other]
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Title: Efficient Microcanonical Histogram Analysis and Application to Peptide AggregationTitle: 高效微正则直方图分析及其在肽聚集中的应用Comments: 6 pages, 2 figuresJournal-ref: Phys. Rev. Lett. 135, 138401 (2025)Subjects: Statistical Mechanics (cond-mat.stat-mech) ; Soft Condensed Matter (cond-mat.soft) ; Biological Physics (physics.bio-ph)
A novel approach designed to directly estimate microcanonical quantities from energy histograms is proposed, which enables the immediate systematic identification and classification of phase transitions in physical systems of any size by means of the recently introduced generalized microcanonical inflection-point analysis method. The application to the aggregation problem of GNNQQNY heptapeptides, for which the entire transition sequence is revealed, shows the power of this promising method.
一种新的方法被提出，旨在直接从能量直方图中估计微正则量，该方法通过最近引入的广义微正则拐点分析方法，能够立即系统地识别和分类任何大小物理系统中的相变。 对该问题的聚集问题的应用，即GNNQQNY七肽，整个转变序列被揭示，展示了这一有前途的方法的力量。
Cross submissions (showing 3 of 3 entries )
- [14] arXiv:2407.19955 (replaced) [cn-pdf, pdf, html, other]
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Title: Hydrodynamics of pulsating active liquidsTitle: 脉动活性液体的流体力学Comments: 21 pages, 7 figuresSubjects: Soft Condensed Matter (cond-mat.soft)
Inspired by dense contractile tissues, where cells are subject to periodic deformation, we formulate and study a generic hydrodynamic theory of pulsating active liquids. Combining mechanical and phenomenological arguments, we postulate that the mechanochemical feedback between the local phase, which describes how cells deform due to autonomous driving, and the local density can be described in terms of a free energy. We demonstrate that such a feedback is compatible with the coarse-graining of a broad class of microscopic models. Our hydrodynamics captures the three main states emerging in its particle-based counterparts: a globally cycling state, a homogeneous arrested state with constant phase, and a state with propagating radial waves. Remarkably, we show that the competition between these states can be rationalized intuitively in terms of an effective landscape, and argue that waves can be regarded as secondary instabilities. Linear stability analysis of the arrested and cycling states, including the role of fluctuations, leads to predictions for the phase boundaries. Overall, our results demonstrate that our minimal, yet non-trivial model provides a relevant platform to study the rich phenomenology of pulsating liquids.
受致密收缩组织的启发，其中细胞受到周期性变形的影响，我们制定并研究了一种脉动活性液体的通用流体力学理论。 结合力学和现象学论证，我们假设局部相与局部密度之间的机械化学反馈可以以自由能的形式描述，其中局部相描述了细胞由于自主驱动而变形的方式。 我们证明这种反馈与一大类微观模型的粗粒化是兼容的。 我们的流体力学捕捉到了其基于粒子的对应物中出现的三种主要状态：一个全局循环状态，一个具有恒定相的均匀冻结状态，以及一个具有传播径向波的状态。 值得注意的是，我们表明这些状态之间的竞争可以通过一个有效景观进行直观解释，并认为波可以被视为次级不稳定性。 对冻结状态和循环状态的线性稳定性分析，包括涨落的作用，导致了相边界预测。 总体而言，我们的结果表明，我们的最小但非平凡的模型提供了一个相关平台，用于研究脉动液体丰富的现象学。
- [15] arXiv:2407.21710 (replaced) [cn-pdf, pdf, html, other]
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Title: Entropic Clustering of Stickers Induces Aging in BiocondensatesTitle: 熵聚类诱导生物凝聚物老化Comments: 18 pages, 5 main figures, and 3 supplementary figuresSubjects: Soft Condensed Matter (cond-mat.soft) ; Biological Physics (physics.bio-ph)
Biomolecular condensates are cellular phase-separated droplets that usually exhibit a viscoelastic mechanical response. A behavior rationalized by modeling the complex molecules that make up a condensate as stickers and spacers, which assemble into a network-like structure. Condensates usually exhibit a solidification over a long period of time (days), a phenomenon described as aging.The emergence of such a long timescale of evolution from microscopic processes, as well as the associated microscopic reorganization leading to aging, remains mostly an open question. In this article, we explore the connection between the mechanical properties of the condensates and their microscopic structure. We propose a minimal model for the dynamic of stickers and spacers, and show that entropy maximization of spacers leads to an attractive force between stickers. Our system displays a surprisingly slow relaxation toward equilibrium, reminiscent of glassy systems and consistent with the liquid-to-solid transition observed. To explain this behavior, we study the clustering dynamic of stickers and successfully explain the origin of glassy relaxation.
生物分子凝聚物是细胞相分离的液滴，通常表现出粘弹性机械响应。 这种行为通过将构成凝聚物的复杂分子建模为粘附剂和间隔物，它们组装成类似网络的结构来解释。 凝聚物通常在较长时间（几天）内表现出固化现象，这一现象被称为老化。从微观过程出现如此长的时间尺度，以及导致老化的相关微观重组，仍然是一个开放性问题。 在本文中，我们探讨了凝聚物的力学性质与其微观结构之间的联系。 我们提出了一个关于粘附剂和间隔物动态的最小模型，并表明间隔物的熵最大化会导致粘附剂之间的吸引力。 我们的系统表现出一种令人惊讶的缓慢弛豫趋向平衡，类似于玻璃系统，并与观察到的液态到固态的转变一致。 为了解释这种行为，我们研究了粘附剂的聚类动态，并成功解释了玻璃状弛豫的起源。
- [16] arXiv:2506.09858 (replaced) [cn-pdf, pdf, html, other]
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Title: Critical surface phase behavior governs hydrophobic attraction between extended solutesTitle: 临界表面相行为支配扩展溶质之间的疏水吸引Comments: 22 pages, 16 figuresSubjects: Soft Condensed Matter (cond-mat.soft)
Hydrophobic interactions are central to biological self-assembly and soft matter organization, yet their microscopic origins remain debated. A key hallmark is the strengthening of attraction between hydrophobic solutes with increasing temperature, a feature often attributed to entropy changes from disrupted hydrogen bonding in water. Here we present an alternative framework based on surface phase behavior, supported by extensive molecular dynamics simulations. Using metadynamics, we quantify the solvent-mediated effective potential between nanometer-scale hydrophobic solutes in the monatomic water (mW) model, the SPCE water model, and a Lennard-Jones solvent. We develop a morphometric model which incorporates a scaling theory of critical drying, linking the range and strength of hydrophobic attraction to interfacial thermodynamics and proximity to vapor-liquid coexistence. The model reproduces the effective potential across diverse solute sizes, degrees of hydrophobicity, and thermodynamic states. Our simulations recover the inverse temperature dependence of hydrophobicity, showing it arises generically from rapid thermal expansion of the solvation shell.
疏水相互作用在生物自组装和软物质组织中起核心作用，但其微观起源仍存在争议。 一个关键特征是随着温度的升高，疏水溶质之间的吸引力增强，这一特性通常归因于水中氢键破坏引起的熵变。 在这里，我们提出了一种基于表面相行为的替代框架，并通过大量分子动力学模拟得到支持。 使用元动力学，我们量化了纳米尺度疏水溶质在单原子水(mW)模型、SPCE水模型和Lennard-Jones溶剂中的溶剂介导的有效势。 我们开发了一个形态学模型，该模型结合了临界干燥的标度理论，将疏水吸引的范围和强度与界面热力学以及接近气液共存的状态联系起来。 该模型能够再现不同溶质尺寸、疏水程度和热力学状态下的有效势。 我们的模拟恢复了疏水性的反温度依赖性，表明它通常来源于溶剂化壳层的快速热膨胀。
- [17] arXiv:2507.04908 (replaced) [cn-pdf, pdf, html, other]
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Title: Computing dielectric spectra in molecular dynamics simulations: using a cavity to disentangle self and cross correlationsTitle: 计算分子动力学模拟中的介电谱：使用空腔来区分自相关和交叉相关Comments: 10 pages, 8 figures, 2 tablesJournal-ref: Marceau H\'enot; Computing dielectric spectra in molecular dynamics simulations: Using a cavity to disentangle self and cross correlations. J. Chem. Phys. 28 September 2025; 163 (12): 124501Subjects: Soft Condensed Matter (cond-mat.soft)
Dielectric spectra are typically obtained in molecular dynamics (MD) simulations by analyzing the fluctuations, in the absence of an applied electric field, of the total dipole moment of the simulation box. We compare this standard method with a protocol that focuses on a virtual cavity whose size is chosen to include short-range dipolar cross-correlations, while excluding long-range correlations that are affected by the choice of electrostatic boundary conditions. We tested this protocol on three non-polarizable systems with different dielectric permittivities. We showed that it produces the same dielectric spectra as the standard method while being less sensitive to noise. The question of the decomposition of a dielectric spectrum into self and cross contributions is discussed in the context of both methods. We propose that, for a liquid with a sufficiently high dielectric permittivity, the cavity protocol yields a self-spectrum consistent with the electrostatic boundary conditions applicable to the experimental situation.
介电谱通常通过分析在没有施加电场的情况下，模拟箱的总偶极矩的波动来获得分子动力学 (MD) 模拟。 我们比较了这种标准方法与一种专注于虚拟腔体的协议，该腔体的大小选择以包含短程偶极交叉相关性，同时排除受静电边界条件选择影响的长程相关性。 我们在三个不同介电常数的不可极化系统上测试了此协议。 我们证明了它产生的介电谱与标准方法相同，同时对噪声更不敏感。 在两种方法的背景下讨论了将介电谱分解为自贡献和交叉贡献的问题。 我们认为，对于具有足够高介电常数的液体，腔协议产生的自谱与适用于实验情况的静电边界条件一致。
- [18] arXiv:2507.05038 (replaced) [cn-pdf, pdf, other]
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Title: Particle-scale origin of quadrupolar non-affine displacement fields in granular solidsTitle: 颗粒尺度上颗粒固体中四极非仿射位移场的起源Evan P. Willmarth, Weiwei Jin, Dong Wang, Amit Datye, Udo D. Schwarz, Mark D. Shattuck, Corey S. O'HernSubjects: Soft Condensed Matter (cond-mat.soft)
In this work, we identify the local structural defects that control the non-affine displacement fields in jammed disk packings subjected to athermal, quasistatic (AQS) simple shear. While complex non-affine displacement fields typically occur during simple shear, isolated effective quadrupoles are also observed and their probability increases with increasing pressure. We show that the emergence of an isolated effective quadrupole requires the breaking of an interparticle contact that is aligned with low-frequency, spatially extended vibrational modes. Since the Eshelby inhomogeneity problem gives rise to quadrupolar displacement fields in continuum materials, we reformulate and implement Eshelby's equivalent inclusion method (EIM) for jammed disk packings. Using EIM, we show that we can reconstruct the non-affine displacement fields for jammed disk packings in response to applied shear as a sum of discrete Eshelby-like defects that are caused by mismatches in the local stiffnesses of triangles formed from Delaunay triangulation of the disk centers.
在本工作中，我们确定了控制受无热准静态（AQS）简单剪切作用的密集盘堆中非仿射位移场的局部结构缺陷。 尽管在简单剪切过程中通常会出现复杂的非仿射位移场，但也观察到了孤立的有效四极子，其概率随着压力的增加而增加。 我们表明，孤立有效四极子的出现需要破坏与低频、空间扩展振动模式对齐的粒子间接触。 由于Eshelby非均匀性问题会在连续材料中产生四极位移场，我们将Eshelby等效夹杂方法（EIM）重新表述并应用于密集盘堆。 使用EIM，我们证明可以将密集盘堆在施加剪切时的非仿射位移场作为由三角形局部刚度不匹配引起的离散Eshelby类似缺陷的总和进行重建，这些三角形是由盘中心的Delaunay三角剖分形成的。
- [19] arXiv:2509.14692 (replaced) [cn-pdf, pdf, html, other]
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Title: A General Model for Static Contact AnglesTitle: 静态接触角的一般模型Comments: 14 pages, 4 figuresSubjects: Soft Condensed Matter (cond-mat.soft) ; Fluid Dynamics (physics.flu-dyn)
The problem of contact angle and hysteresis determination has direct implications for engineering applications of wetting, colloid and surface science. Significant technical challenges can arise under real-world operating conditions, because the static contact angle is strongly influenced by contamination at the liquid-solid and liquid-vapor interfaces, chemical aging over long times, and environmental variables such as relative humidity and temperature. Analytical models that account for these real-world effects are therefore highly desirable to guide the rational design of robust applications. This work proposes a unified and simple-to-use model that expands Young's local thermodynamic approach to consider surfaces with topographic features of general geometry and varying degrees of liquid infiltration. The unified model recovers classical wetting limits (Wenzel, Cassie-Baxter, and hemiwicking), accounts for observable intermediate states (e.g., impregnating Cassie), and identifies a new limiting state with potential realizability: a Cassie state accompanied by a precursor film, termed the Inverse Wenzel state.
接触角和滞后性的确定问题对润湿性、胶体和表面科学的工程应用具有直接意义。 在实际运行条件下，可能会出现重大的技术挑战，因为静态接触角受到液体-固体和液体-蒸汽界面污染、长时间的化学老化以及相对湿度和温度等环境变量的强烈影响。 因此，能够考虑这些现实因素的分析模型对于指导稳健应用的合理设计是非常理想的。 本工作提出了一种统一且易于使用的新模型，该模型扩展了杨氏的局部热力学方法，以考虑具有通用几何结构和不同液体渗透程度的表面。 该统一模型恢复了经典的润湿极限（Wenzel、Cassie-Baxter 和半浸润），考虑了可观察到的中间状态（例如，浸润的 Cassie 状态），并识别了一个具有潜在可实现性的新极限状态：伴随前驱膜的 Cassie 状态，称为逆 Wenzel 状态。
- [20] arXiv:2509.15341 (replaced) [cn-pdf, pdf, html, other]
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Title: Competing Supramolecular Structures: Dielectric and Rheological Spectroscopy on Glycerol/Propanol MixturesTitle: 竞争的超分子结构：甘油/丙醇混合物的介电和流变光谱Subjects: Soft Condensed Matter (cond-mat.soft)
Significant progress has been made in recent years in understanding the dynamics of pure hydrogen-bonded systems by analyzing the spectral shape of various susceptibilities. Monohydroxy- and polyalcohols are currently considered to form transient supramolecular hydrogen-bonded structures in the form of chains, rings, and networks. This complex dynamic behavior has been identified in network-forming glycerol and chain-forming propanol by combining dielectric and light-scattering spectra. We apply these concepts to study the combined dielectric and shear rheological spectral shape of glycerol/propanol mixtures. Glycerol differs from propanol by having two additional hydroxy groups, which leads to significant differences in melting temperatures($\Delta T_{\textbf{m}}$\,=\,291\,K\,-\,147\,K\,=\,143\,K) and glass transition temperatures ($\Delta T_{\textbf{g}}$\,=\,190\,K-\,98\,K\,=\,92\,K). The strong difference results in two distinct calorimetric glass transitions at a molar glycerol concentration of $\chi_{gly}=0.3$, as well as a change in the shear modulus $G_{\infty}$ between $\chi_{gly}=0.5$ and 0.7. Performing a comprehensive analysis of the three applied experimental techniques leads to the conclusion that dielectric spectroscopy monitors the evolution of supramolecular chain and network structures and that the mechanical properties depend heavily on the formed hydrogen-bonded network. A strong dynamical heterogeneity is observed and manifests itself in two distinguishable glass transitions in dielectric spectroscopy and calorimetry. The presented chain/network mixture is dynamically highly heterogeneous when compared to the rather narrow dynamical heterogeneity in the network/network mixture Water/Glycerol.
近年来，通过分析各种极化率的光谱形状，对纯氢键系统的动力学有了显著进展。 单羟基和多元醇目前被认为会形成瞬态的超分子氢键结构，形式为链、环和网络。 通过结合介电和光散射光谱，已在成网的甘油和成链的丙醇中识别出这种复杂的动态行为。 我们将这些概念应用于研究甘油/丙醇混合物的介电和剪切流变光谱形状。 甘油与丙醇的不同之处在于它多两个羟基，这导致熔点（$\Delta T_{\textbf{m}}$= 291 K - 147 K = 143 K）和玻璃化转变温度（$\Delta T_{\textbf{g}}$= 190 K - 98 K = 92 K）有显著差异。 这种强烈的差异导致在摩尔甘油浓度为$\chi_{gly}=0.3$时出现两个不同的量热玻璃化转变，以及剪切模量$G_{\infty}$在$\chi_{gly}=0.5$和 0.7 之间的变化。 对三种应用的实验技术进行全面分析得出结论，介电光谱监测超分子链和网络结构的演变，而机械性能则高度依赖于形成的氢键网络。 观察到强烈的动态异质性，并在介电光谱和量热法中表现出两个可区分的玻璃化转变。 与网络/网络混合物中的较窄动态异质性相比，所提出的链/网络混合物在动态上高度异质。 水/甘油。
- [21] arXiv:2508.11586 (replaced) [cn-pdf, pdf, html, other]
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Title: Measuring irreversibility by counting: a random coarse-graining frameworkTitle: 通过计数测量不可逆性：一种随机粗粒化框架Comments: 5+3 pages, 2 figures, some typos are corrected, Fig. 2 has been replacedSubjects: Statistical Mechanics (cond-mat.stat-mech) ; Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ; Soft Condensed Matter (cond-mat.soft) ; Biological Physics (physics.bio-ph)
Thermodynamic irreversibility is a fundamental concept in statistical physics, yet its experimental measurement remains challenging, especially for complex systems. We introduce a novel random coarse-graining framework to identify model-free measures of irreversibility in complex many-body systems. These measures are constructed from the asymmetry of cross-correlation functions between suitably chosen observables, providing rigorous lower bounds on entropy production. For many-particle systems, we propose a particularly practical implementation that divides real space into virtual boxes and monitors particle number densities within them, requiring only simple counting from video microscopy, without single-particle tracking, trajectory reconstruction, or prior knowledge of interactions. Owing to its generality and minimal data requirements, the random coarse-graining framework offers broad applicability across diverse nonequilibrium systems.
热力学不可逆性是统计物理中的一个基本概念，但其实验测量仍然具有挑战性，尤其是在复杂系统中。 我们引入了一种新颖的随机粗粒化框架，以在复杂多体系统中识别模型无关的不可逆性度量。 这些度量是从适当选择的可观测量之间的交叉相关函数的不对称性构建的，提供了熵产生的严格下限。 对于多粒子系统，我们提出了一种特别实用的实现方法，将真实空间划分为虚拟盒子，并监测其中的粒子数密度，只需要从视频显微镜中进行简单的计数，而无需单粒子追踪、轨迹重建或对相互作用的先验知识。 由于其普遍性和最小的数据需求，随机粗粒化框架在各种非平衡系统中具有广泛的应用前景。