It is generally assumed that hydrodynamics in dense polyelectrolyte (PE) solutions, such as semidilute PE solutions and PE complex coacervates, is heavily screened and inconsequential. Here, using mesoscale molecular dynamics that explicitly accounts for hydrodynamics, we show that segmental dynamics in the subdiffusive regime show strong signatures of hydrodynamic interactions that persist well beyond the correlation length of semidilute PE solutions with moderately short chains. The strong hydrodynamic effects are also observed in coacervate systems containing moderately short chains, even with PE concentration as high as $30%$. Our work fills a gap in the existing simulation literature on dense PE solutions and hints at the importance of hydrodynamics in the transport and rheological properties in broader polymer/polyelectrolyte solution systems.
{"title":"Hydrodynamics in Semidilute Polyelectrolyte Solutions and Complex Coacervates","authors":"Shensheng Chen, Zhen-Gang Wang","doi":"arxiv-2409.09450","DOIUrl":"https://doi.org/arxiv-2409.09450","url":null,"abstract":"It is generally assumed that hydrodynamics in dense polyelectrolyte (PE)\u0000solutions, such as semidilute PE solutions and PE complex coacervates, is\u0000heavily screened and inconsequential. Here, using mesoscale molecular dynamics\u0000that explicitly accounts for hydrodynamics, we show that segmental dynamics in\u0000the subdiffusive regime show strong signatures of hydrodynamic interactions\u0000that persist well beyond the correlation length of semidilute PE solutions with\u0000moderately short chains. The strong hydrodynamic effects are also observed in\u0000coacervate systems containing moderately short chains, even with PE\u0000concentration as high as $30%$. Our work fills a gap in the existing\u0000simulation literature on dense PE solutions and hints at the importance of\u0000hydrodynamics in the transport and rheological properties in broader\u0000polymer/polyelectrolyte solution systems.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"102 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Plastic pollution, mainly from lost fishing gear composed of high-density polyethylene (HDPE) and polypropylene (PP), poses a significant environmental obstacle. This study evaluates the potential of recycling PP from fishnet/rope and reinforcing it with glass fiber (GF) in the form of 3D printer filaments as a way to reduce/prevent ocean plastic. Two materials, one virgin (vPP-GF) and one made up of recycled polypropylene and virgin glass fibers (rPP-GF), were analyzed using differential scanning calorimetry, tensile, and Charpy impact tests. From the results, it was found that rPP-GF often outperformed vPP-GF. rPP-GF had a higher melting and crystallization point, likely a higher crystallinity, and could withstand a higher tensile stress, while vPP-GF could withstand a higher tensile strain. Further analysis revealed the potential presence of HDPE within the rPP-GF composite, which was not reported by the manufacturer. This significantly affected the Charpy test and made it difficult to draw conclusions from the resulting data. Nevertheless, their comparability in terms of mechanical and material properties indicates the strong potential of recycling polypropylene fishnet/rope and reinforcing it with glass fibers to extend their lifespan and reduce ocean plastic.
塑料污染主要来自由高密度聚乙烯（HDPE）和聚丙烯（PP）组成的遗失渔具，对环境造成了严重危害。本研究评估了从鱼网/绳索中回收聚丙烯，并用玻璃纤维（GF）以 3D 打印机丝的形式对其进行增强的潜力，以此减少/防止海洋塑料的产生。使用差示扫描量热仪、拉伸和夏比冲击试验分析了两种材料，一种是原生材料（vPP-GF），另一种是由回收聚丙烯和原生玻璃纤维组成的材料（rPP-GF）。结果发现，rPP-GF 的性能往往优于 vPP-GF。rPP-GF 的熔点和结晶点更高，结晶度可能更高，能承受更大的拉伸应力，而 vPP-GF 能承受更大的拉伸应变。进一步的分析表明，在 rPP-GF 复合材料中可能存在高密度聚乙烯（HDPE），但生产商并未报告。这严重影响了夏比试验，使我们难以从所得数据中得出结论。尽管如此，它们在机械和材料特性方面的可比性表明，回收聚丙烯鱼网/绳并用玻璃纤维进行增强以延长其使用寿命和减少海洋塑料的潜力巨大。
{"title":"The Properties of Glass Fiber Reinforced Polypropylene Filaments Recycled from Fishing Gear","authors":"Garrett Russell","doi":"arxiv-2409.09445","DOIUrl":"https://doi.org/arxiv-2409.09445","url":null,"abstract":"Plastic pollution, mainly from lost fishing gear composed of high-density\u0000polyethylene (HDPE) and polypropylene (PP), poses a significant environmental\u0000obstacle. This study evaluates the potential of recycling PP from fishnet/rope\u0000and reinforcing it with glass fiber (GF) in the form of 3D printer filaments as\u0000a way to reduce/prevent ocean plastic. Two materials, one virgin (vPP-GF) and\u0000one made up of recycled polypropylene and virgin glass fibers (rPP-GF), were\u0000analyzed using differential scanning calorimetry, tensile, and Charpy impact\u0000tests. From the results, it was found that rPP-GF often outperformed vPP-GF.\u0000rPP-GF had a higher melting and crystallization point, likely a higher\u0000crystallinity, and could withstand a higher tensile stress, while vPP-GF could\u0000withstand a higher tensile strain. Further analysis revealed the potential\u0000presence of HDPE within the rPP-GF composite, which was not reported by the\u0000manufacturer. This significantly affected the Charpy test and made it difficult\u0000to draw conclusions from the resulting data. Nevertheless, their comparability\u0000in terms of mechanical and material properties indicates the strong potential\u0000of recycling polypropylene fishnet/rope and reinforcing it with glass fibers to\u0000extend their lifespan and reduce ocean plastic.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Pedro de Souza, William M. Jacobs, Howard A. Stone
Polymer mixtures fractionate between phases depending on their molecular weight. Consequently, by varying solvent conditions, a polydisperse polymer sample can be separated between phases so as to achieve a particular molecular weight distribution in each phase. In principle, predictive physics-based theories can help guide separation design and interpret experimental fractionation measurements. Even so, applying the standard Flory-Huggins model can present a computational challenge for mixtures with many polymeric components of different length, particularly for scarce components at the tails of a distribution. Here, we apply our recently-derived exact analytical solution of multi-component Flory-Huggins theory for polydisperse polymers to understand the principles of polymer fractionation for common molecular weight distributions. Our method reveals that polymer fractionation is highly sensitive to the shape, and in particular the tails, of this distribution. Our results highlight the need for considering the full molecular weight distribution in phase coexistence calculations.
{"title":"Polydisperse polymer fractionation between phases","authors":"J. Pedro de Souza, William M. Jacobs, Howard A. Stone","doi":"arxiv-2409.09229","DOIUrl":"https://doi.org/arxiv-2409.09229","url":null,"abstract":"Polymer mixtures fractionate between phases depending on their molecular\u0000weight. Consequently, by varying solvent conditions, a polydisperse polymer\u0000sample can be separated between phases so as to achieve a particular molecular\u0000weight distribution in each phase. In principle, predictive physics-based\u0000theories can help guide separation design and interpret experimental\u0000fractionation measurements. Even so, applying the standard Flory-Huggins model\u0000can present a computational challenge for mixtures with many polymeric\u0000components of different length, particularly for scarce components at the tails\u0000of a distribution. Here, we apply our recently-derived exact analytical\u0000solution of multi-component Flory-Huggins theory for polydisperse polymers to\u0000understand the principles of polymer fractionation for common molecular weight\u0000distributions. Our method reveals that polymer fractionation is highly\u0000sensitive to the shape, and in particular the tails, of this distribution. Our\u0000results highlight the need for considering the full molecular weight\u0000distribution in phase coexistence calculations.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nearly thirty years after its inception, the field of DNA-programmed colloidal self-assembly has begun to realize its initial promise. In this review, we summarize recent developments in designing effective interactions and understanding the dynamic self-assembly pathways of DNA-coated nanoparticles and microparticles, as well as how these advances have propelled tremendous progress in crystal engineering. We also highlight exciting new directions showing that new classes of subunits combining nanoparticles with DNA origami can be used to engineer novel multicomponent assemblies, including structures with self-limiting, finite sizes. We conclude by providing an outlook on how recent theoretical advances focusing on the kinetics of self-assembly could usher in new materials-design opportunities, like the possibility of retrieving multiple distinct target structures from a single suspension or accessing new classes of materials that are stabilized by energy dissipation, mimicking self-assembly in living systems.
DNA 编程胶体自组装领域在诞生近三十年后已开始实现其最初的承诺。在这篇综述中，我们总结了在设计有效的相互作用和理解 DNA 涂层纳米颗粒和微颗粒的动态自组装途径方面的最新进展，以及这些进展如何推动了晶体工程学的巨大进步。我们还重点介绍了令人兴奋的新方向，这些方向表明，结合了纳米粒子和 DNA 折纸的新型亚基可用于设计新型多组分组装体，包括具有自我限制的有限尺寸的结构。最后，我们展望了最近以自组装动力学为重点的理论研究进展如何带来新的材料设计机遇，例如从单一悬浮液中提取多种不同目标结构的可能性，或获得通过能量耗散而稳定的新型材料，从而模拟生命系统中的自组装。
{"title":"Assembly of Complex Colloidal Systems Using DNA","authors":"William M. Jacobs, W. Benjamin Rogers","doi":"arxiv-2409.08988","DOIUrl":"https://doi.org/arxiv-2409.08988","url":null,"abstract":"Nearly thirty years after its inception, the field of DNA-programmed\u0000colloidal self-assembly has begun to realize its initial promise. In this\u0000review, we summarize recent developments in designing effective interactions\u0000and understanding the dynamic self-assembly pathways of DNA-coated\u0000nanoparticles and microparticles, as well as how these advances have propelled\u0000tremendous progress in crystal engineering. We also highlight exciting new\u0000directions showing that new classes of subunits combining nanoparticles with\u0000DNA origami can be used to engineer novel multicomponent assemblies, including\u0000structures with self-limiting, finite sizes. We conclude by providing an\u0000outlook on how recent theoretical advances focusing on the kinetics of\u0000self-assembly could usher in new materials-design opportunities, like the\u0000possibility of retrieving multiple distinct target structures from a single\u0000suspension or accessing new classes of materials that are stabilized by energy\u0000dissipation, mimicking self-assembly in living systems.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aleksandra Deptuch, Natalia Górska, Stanisław Baran, Magdalena Urbańska
Molecular arrangement in the chiral smectic phases of the glassforming (S)-4'-(1-methylheptylcarbonyl)biphenyl-4-yl 4-[7-(2,2,3,3,4,4,4-heptafluorobutoxy) heptyl-1-oxy]benzoate is investigated by X-ray diffraction. An increased correlation length of the positional short-range order in the supercooled state agrees with the previous assumption of the hexatic smectic phase. However, the registered X-ray diffraction patterns are not typical for the hexatic phases. Comparison of the smectic layer spacing and optical tilt angle indicates a strongly non-linear shape of molecules, which enables choice of the molecular models obtained by DFT calculations, used subsequently to interpret the infra-red spectra. The presumption of the hexatic smectic FA* or IA* phase is supported by the splitting of the absorption bands related to the C=O stretching in the supercooled state, which is absent in the smectic CA* phase above the melting temperature. The glass transition affects the temperature dependence of the smectic layer spacing but only subtly impacts the infra-red spectra. Application of the k-means cluster analysis enables distinction between the infra-red spectra below and above the glass transition temperature, but only for certain spectral ranges.
通过 X 射线衍射研究了玻璃化(S)-4'-(1-甲基庚羰基)联苯-4-基-4-[7-(2,2,3,3,4,4,4-七氟丁氧基)庚基-1-氧基]苯甲酸酯手性共晶相中的分子排列。在过冷状态下，位置短程阶相关长度增加，这与之前假设的六方共晶相相吻合。然而，所记录的 X 射线衍射图样并不是典型的六方相。对晶层间距和光学倾斜角的比较表明，分子的形状具有很强的非线性，因此可以选择通过 DFT 计算得到的分子模型，随后用来解释红外光谱。在过冷状态下，与 C=O 伸展相关的吸收带出现分裂，而在熔融温度以上的共晶 CA* 相中则没有这种分裂，这支持了六方共晶 FA* 或 IA* 相的推测。玻璃化转变会影响共晶层间距的温度依赖性，但只会对红外光谱产生微妙的影响。应用 k-means 聚类分析可以区分玻璃化转变温度以下和玻璃化转变温度以上的红外光谱，但仅限于某些光谱范围。
{"title":"Structural and dynamical investigation of glassforming smectogen by X-ray diffraction and infra-red spectroscopy aided by density functional theory calculations","authors":"Aleksandra Deptuch, Natalia Górska, Stanisław Baran, Magdalena Urbańska","doi":"arxiv-2409.08654","DOIUrl":"https://doi.org/arxiv-2409.08654","url":null,"abstract":"Molecular arrangement in the chiral smectic phases of the glassforming\u0000(S)-4'-(1-methylheptylcarbonyl)biphenyl-4-yl\u00004-[7-(2,2,3,3,4,4,4-heptafluorobutoxy) heptyl-1-oxy]benzoate is investigated by\u0000X-ray diffraction. An increased correlation length of the positional\u0000short-range order in the supercooled state agrees with the previous assumption\u0000of the hexatic smectic phase. However, the registered X-ray diffraction\u0000patterns are not typical for the hexatic phases. Comparison of the smectic\u0000layer spacing and optical tilt angle indicates a strongly non-linear shape of\u0000molecules, which enables choice of the molecular models obtained by DFT\u0000calculations, used subsequently to interpret the infra-red spectra. The\u0000presumption of the hexatic smectic FA* or IA* phase is supported by the\u0000splitting of the absorption bands related to the C=O stretching in the\u0000supercooled state, which is absent in the smectic CA* phase above the melting\u0000temperature. The glass transition affects the temperature dependence of the\u0000smectic layer spacing but only subtly impacts the infra-red spectra.\u0000Application of the k-means cluster analysis enables distinction between the\u0000infra-red spectra below and above the glass transition temperature, but only\u0000for certain spectral ranges.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cristóbal Romero-Guzmán, Iván M. Zerón, Jesús Algaba, Bruno Mendiboure, José Manuel Míguez, Felipe J. Blas
We investigate the effect of pressure on the carbon dioxide (CO$_{2}$) hydrate-water interfacial free energy along its dissociation line using advanced computer simulation techniques. In previous works, we have determined the interfacial energy of the hydrate at $400 ,text{bar}$ using the TIP4P/ice and TraPPE molecular models for water and CO$_{2}$, respectively, in combination with two different extensions of the Mold Integration technique [J. Chem. Phys. 141, 134709 (2014)]. Results obtained from computer simulation, $29(2)$ and $30(2),text{mJ/m}^{2}$, are found to be in excellent agreement with the only two measurements that exist in the literature, $28(6),text{mJ/m}^{2}$ determined by Uchida et al. [J. Phys. Chem. B 106, 8202 (2002)] and $30(3),text{mJ/m}^{2}$ by Anderson et al. [J. Phys. Chem. B 107, 3507 (2002)]. Since the experiments do not allow to obtain the variation of the interfacial energy along the dissociation line of the hydrate, we extend our previous studies to quantify the effect of pressure on the interfacial energy at different pressures. Our results suggest that there exists a correlation between the interfacial free energy values and the pressure, i.e., it decreases with the pressure between $100$ and $1000,text{bar}$. We expect that the combination of reliable molecular models and advanced simulation techniques could help to improve our knowledge of the thermodynamic parameters that control the interfacial free energy of hydrates from a molecular perspective.
{"title":"Effect of pressure on the carbon dioxide hydrate-water interfacial free energy along its dissociation line","authors":"Cristóbal Romero-Guzmán, Iván M. Zerón, Jesús Algaba, Bruno Mendiboure, José Manuel Míguez, Felipe J. Blas","doi":"arxiv-2409.07844","DOIUrl":"https://doi.org/arxiv-2409.07844","url":null,"abstract":"We investigate the effect of pressure on the carbon dioxide (CO$_{2}$)\u0000hydrate-water interfacial free energy along its dissociation line using\u0000advanced computer simulation techniques. In previous works, we have determined\u0000the interfacial energy of the hydrate at $400 ,text{bar}$ using the TIP4P/ice\u0000and TraPPE molecular models for water and CO$_{2}$, respectively, in\u0000combination with two different extensions of the Mold Integration technique [J.\u0000Chem. Phys. 141, 134709 (2014)]. Results obtained from computer simulation,\u0000$29(2)$ and $30(2),text{mJ/m}^{2}$, are found to be in excellent agreement\u0000with the only two measurements that exist in the literature,\u0000$28(6),text{mJ/m}^{2}$ determined by Uchida et al. [J. Phys. Chem. B 106,\u00008202 (2002)] and $30(3),text{mJ/m}^{2}$ by Anderson et al. [J. Phys. Chem. B\u0000107, 3507 (2002)]. Since the experiments do not allow to obtain the variation\u0000of the interfacial energy along the dissociation line of the hydrate, we extend\u0000our previous studies to quantify the effect of pressure on the interfacial\u0000energy at different pressures. Our results suggest that there exists a\u0000correlation between the interfacial free energy values and the pressure, i.e.,\u0000it decreases with the pressure between $100$ and $1000,text{bar}$. We expect\u0000that the combination of reliable molecular models and advanced simulation\u0000techniques could help to improve our knowledge of the thermodynamic parameters\u0000that control the interfacial free energy of hydrates from a molecular\u0000perspective.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carmen L. Lee, Ephraim Bililign, Emilien Azéma, Karen E. Daniels
The bulk behaviour of granular materials is tied to its mesoscale and particle-scale features: strength properties arise from the buildup of various anisotropic structures at the particle-scale induced by grain connectivity (fabric), force transmission, and frictional mobilization. More fundamentally, these anisotropic structures work collectively to define features like the bulk friction coefficient and the stress tensor at the macroscale and can be explained by the Stress-Force-Fabric (SFF) relationship stemming from the microscale. Although the SFF relation has been extensively verified by discrete numerical simulations, a laboratory realization has remained elusive due to the challenge of measuring both normal and frictional contact forces. In this study, we analyze experiments performed on a photoelastic granular system under four different loading conditions: uniaxial compression, isotropic compression, pure shear, and annular shear. During these experiments, we record particle locations, contacts, and normal and frictional forces vectors to measure the particle-scale response to progressing strain. We track microscale measures like the packing fraction, average coordination number and average normal force along with anisotropic distributions of contacts and forces. We match the particle-scale anisotropy to the bulk using the SFF relation, which is founded on two key principles, a Stress Rule to describe the stress tensor and a Sum Rule to describe the bulk friction coefficient; we find that the Sum and Stress Rules accurately describe bulk measurements. Additionally, we test the assumption that fabric and forces transmit load equally through our granular packings and show that this assumption is sufficient at large strain values, and can be applied to areas like rock mechanics, soft colloids, or cellular tissue where force information is inaccessible.
{"title":"Loading-dependent microscale measures control bulk properties in granular material: an experimental test of the Stress-Force-Fabric relation","authors":"Carmen L. Lee, Ephraim Bililign, Emilien Azéma, Karen E. Daniels","doi":"arxiv-2409.08140","DOIUrl":"https://doi.org/arxiv-2409.08140","url":null,"abstract":"The bulk behaviour of granular materials is tied to its mesoscale and\u0000particle-scale features: strength properties arise from the buildup of various\u0000anisotropic structures at the particle-scale induced by grain connectivity\u0000(fabric), force transmission, and frictional mobilization. More fundamentally,\u0000these anisotropic structures work collectively to define features like the bulk\u0000friction coefficient and the stress tensor at the macroscale and can be\u0000explained by the Stress-Force-Fabric (SFF) relationship stemming from the\u0000microscale. Although the SFF relation has been extensively verified by discrete\u0000numerical simulations, a laboratory realization has remained elusive due to the\u0000challenge of measuring both normal and frictional contact forces. In this\u0000study, we analyze experiments performed on a photoelastic granular system under\u0000four different loading conditions: uniaxial compression, isotropic compression,\u0000pure shear, and annular shear. During these experiments, we record particle\u0000locations, contacts, and normal and frictional forces vectors to measure the\u0000particle-scale response to progressing strain. We track microscale measures\u0000like the packing fraction, average coordination number and average normal force\u0000along with anisotropic distributions of contacts and forces. We match the\u0000particle-scale anisotropy to the bulk using the SFF relation, which is founded\u0000on two key principles, a Stress Rule to describe the stress tensor and a Sum\u0000Rule to describe the bulk friction coefficient; we find that the Sum and Stress\u0000Rules accurately describe bulk measurements. Additionally, we test the\u0000assumption that fabric and forces transmit load equally through our granular\u0000packings and show that this assumption is sufficient at large strain values,\u0000and can be applied to areas like rock mechanics, soft colloids, or cellular\u0000tissue where force information is inaccessible.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142220782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Piotr Nowakowski, Nima Farahmand Bafi, Giovanni Volpe, Svyatoslav Kondrat, S. Dietrich
Critical Casimir forces emerge among particles or surfaces immersed in a near-critical fluid, with the sign of the force determined by surface properties and with its strength tunable by minute temperature changes. Here, we show how such forces can be used to trap a colloidal particle and levitate it above a substrate with a bull's-eye pattern consisting of a ring with surface properties opposite to the rest of the substrate. Using the Derjaguin approximation and mean-field calculations, we find a rich behavior of spherical colloids at such a patterned surface, including sedimentation towards the ring and levitation above the ring (ring levitation) or above the bull's-eye's center (point levitation). Within the Derjaguin approximation, we calculate a levitation diagram for point levitation showing the depth of the trapping potential and the height at which the colloid levitates, both depending on the pattern properties, the colloid size, and the solution temperature. Our calculations reveal that the parameter space associated with point levitation shrinks if the system is driven away from a critical point, while, surprisingly, the trapping force becomes stronger. We discuss the application of critical Casimir levitation for sorting colloids by size and for determining the thermodynamic distance to criticality. Our results show that critical Casimir forces provide rich opportunities for controlling the behavior of colloidal particles at patterned surfaces.
{"title":"Critical Casimir levitation of colloids above a bull's-eye pattern","authors":"Piotr Nowakowski, Nima Farahmand Bafi, Giovanni Volpe, Svyatoslav Kondrat, S. Dietrich","doi":"arxiv-2409.08366","DOIUrl":"https://doi.org/arxiv-2409.08366","url":null,"abstract":"Critical Casimir forces emerge among particles or surfaces immersed in a\u0000near-critical fluid, with the sign of the force determined by surface\u0000properties and with its strength tunable by minute temperature changes. Here,\u0000we show how such forces can be used to trap a colloidal particle and levitate\u0000it above a substrate with a bull's-eye pattern consisting of a ring with\u0000surface properties opposite to the rest of the substrate. Using the Derjaguin\u0000approximation and mean-field calculations, we find a rich behavior of spherical\u0000colloids at such a patterned surface, including sedimentation towards the ring\u0000and levitation above the ring (ring levitation) or above the bull's-eye's\u0000center (point levitation). Within the Derjaguin approximation, we calculate a\u0000levitation diagram for point levitation showing the depth of the trapping\u0000potential and the height at which the colloid levitates, both depending on the\u0000pattern properties, the colloid size, and the solution temperature. Our\u0000calculations reveal that the parameter space associated with point levitation\u0000shrinks if the system is driven away from a critical point, while,\u0000surprisingly, the trapping force becomes stronger. We discuss the application\u0000of critical Casimir levitation for sorting colloids by size and for determining\u0000the thermodynamic distance to criticality. Our results show that critical\u0000Casimir forces provide rich opportunities for controlling the behavior of\u0000colloidal particles at patterned surfaces.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Via numerical simulations and analytical calculations, depletion forces are studied in mixtures of small and big particles that interact via soft repulsive potentials. While big particles are spherical, small particles are nonspherical with shapes that vary gradually, from squares to rods via intermediate shapes. The mixtures are studied for a wide range of densities and temperature. Depletion forces and their resulting potentials depend on the interplay of shape, temperature and density, an argument that is elaborated qualitatively and quantitatively. While in some thermodynamic conditions, depletion potentials of distinct shapes are distinguishable, in different conditions, they are very similar. Finally, I propose novel computational models and experiments for further investigation of the effect of morphology on phase separation in and out of thermal equilibrium.
{"title":"Shape, temperature and density interplay in depletion forces","authors":"Itay Azizi","doi":"arxiv-2409.08209","DOIUrl":"https://doi.org/arxiv-2409.08209","url":null,"abstract":"Via numerical simulations and analytical calculations, depletion forces are\u0000studied in mixtures of small and big particles that interact via soft repulsive\u0000potentials. While big particles are spherical, small particles are nonspherical\u0000with shapes that vary gradually, from squares to rods via intermediate shapes.\u0000The mixtures are studied for a wide range of densities and temperature.\u0000Depletion forces and their resulting potentials depend on the interplay of\u0000shape, temperature and density, an argument that is elaborated qualitatively\u0000and quantitatively. While in some thermodynamic conditions, depletion\u0000potentials of distinct shapes are distinguishable, in different conditions,\u0000they are very similar. Finally, I propose novel computational models and\u0000experiments for further investigation of the effect of morphology on phase\u0000separation in and out of thermal equilibrium.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142220781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using coarse-grained molecular dynamics simulations and a united-monomer model of PE, single well-aligned multi-lamella PE crystals grown in previous work [ACS Macro Letters 12, 808 (2023)] are deformed uniaxially to mimic tensile testing. During deformation, the crystallinity, tie-chain segments, entanglements and folds are monitored and correlated with the stress-strain behaviour and mechanical properties. At small strains, the single well-aligned PE crystals reveal a larger Young modulus when the deformation direction is perpendicular to the global stem direction. At large strains, the memory of the initial topology plays little role in the mechanical response and is observed to be completely destroyed. Short chain branching appears to suppress disentanglement and shear induced alignment of the chains during deformation. As a result, tie-chains and entanglements persist in branched systems and the peak stress at failure is found to be proportional to the change in number of tie-chains from the beginning of the brittle break to its end. Our findings suggest the remarkable mechanical properties of bimodal branched PE result directly from tie-chains, with entanglements playing a secondary role in the mechanical response.
{"title":"Branches, Tie Chains and Entanglements in Bimodal Polyethylene Single Crystals under Uniaxial Tensile Strain","authors":"William S. Fall, Jörg Baschnagel, Hendrik Meyer","doi":"arxiv-2409.08399","DOIUrl":"https://doi.org/arxiv-2409.08399","url":null,"abstract":"Using coarse-grained molecular dynamics simulations and a united-monomer\u0000model of PE, single well-aligned multi-lamella PE crystals grown in previous\u0000work [ACS Macro Letters 12, 808 (2023)] are deformed uniaxially to mimic\u0000tensile testing. During deformation, the crystallinity, tie-chain segments,\u0000entanglements and folds are monitored and correlated with the stress-strain\u0000behaviour and mechanical properties. At small strains, the single well-aligned\u0000PE crystals reveal a larger Young modulus when the deformation direction is\u0000perpendicular to the global stem direction. At large strains, the memory of the\u0000initial topology plays little role in the mechanical response and is observed\u0000to be completely destroyed. Short chain branching appears to suppress\u0000disentanglement and shear induced alignment of the chains during deformation.\u0000As a result, tie-chains and entanglements persist in branched systems and the\u0000peak stress at failure is found to be proportional to the change in number of\u0000tie-chains from the beginning of the brittle break to its end. Our findings\u0000suggest the remarkable mechanical properties of bimodal branched PE result\u0000directly from tie-chains, with entanglements playing a secondary role in the\u0000mechanical response.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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