Frontiers in Soft Matter最新文献

{"title":"Phase transitions in complex functional liquid crystals—The entropy effect","authors":"M. Lehmann","doi":"10.3389/frsfm.2023.1089726","DOIUrl":"https://doi.org/10.3389/frsfm.2023.1089726","url":null,"abstract":"Liquid crystal design and synthesis are being driven towards always more complexity. The self-assembly of poly- and shape-amphiphiles allow tailoring the soft material structures with double and even triple nanosegregation of functional building blocks. Alignment of the anisotropic liquid crystal is crucial, in order to generate a full control over the material’s function and performance. This procedure often needs an isotropic phase at accessible temperatures without decomposition. The impact of thermodynamic factors, such as cohesive energy density difference and entropy contributions, is discussed in this perspective paper using selected examples. In the process of molecular design such considerations can help to adjust transition temperatures and subsequently, to achieve aligned, complex liquid crystalline matter. This will allow access to new fields of liquid crystal applications.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"138 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114488239","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}

{"title":"Physical properties and cellular responses of gelatin methacryloyl bulk hydrogels and highly ordered porous hydrogels","authors":"H. Yin, Mengxiang Zhu, Yingying Wang, Lihua Luo, Qingsong Ye, B. Lee","doi":"10.3389/frsfm.2022.1101680","DOIUrl":"https://doi.org/10.3389/frsfm.2022.1101680","url":null,"abstract":"Protein-based hydrogels hold a high content of water in their three-dimensional (3D) network structure and exhibit innate biological activities as well as soft tissue-like mechanical properties, resulting in being highly applicable to various tissue engineering fields. However, precisely controlling the 3D porous structure of protein-based hydrogels remains a challenging task, and understanding the influence of their porous structure on physical properties and cellular responses is crucial for tissue engineering applications. In this study, we prepared highly ordered gelatin methacryloyl hydrogels with regular interconnected pores and traditional bulk hydrogels with irregular pores to evaluate their differences in physiochemical properties and cellular behaviors. Highly ordered gelatin methacryloyl hydrogels exhibited a high degree of compliance owing to their sponge-like structure whereas gelatin methacryloyl bulk hydrogels exhibited relatively higher moduli but were brittle due to a densely packed structure. The highly ordered gelatin methacryloyl hydrogels with interconnected pores supported higher cell viability (about 100%) due to an efficient flux of oxygen and nutrients compared to the dense bulk hydrogels showing cell viability (around 80%). Also, cells in the highly ordered gelatin methacryloyl hydrogels displayed a more stretched morphology compared to those in the gelatin methacryloyl bulk hydrogels that exhibited a more round morphology during the cell culture period.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115089418","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}

{"title":"Recent advances in biosurfactant-based association colloids—Self-assembly in water","authors":"T. Hellweg, T. Sottmann, J. Oberdisse","doi":"10.3389/frsfm.2022.1081877","DOIUrl":"https://doi.org/10.3389/frsfm.2022.1081877","url":null,"abstract":"Recent studies of self-assembly in binary systems of bio-surfactants, either of microbial origin or saponins extracted from plants, are reviewed. Saponins in water reported in the first section include aescin, glycyrrhizin, and quillaja saponins, while rhamnolipids are discussed in the second section on microbial surfactants. Studies of surface activities are a natural starting point of the characterization of surfactants, but here we focus mainly on physico-chemical and structural properties of self-assembled bulk structures in solution, often characterized by scattering techniques. When quantitative modelling is performed, self-assembly parameters like aggregation numbers, head group areas, and resulting shapes can be followed as a function of physical-chemical parameters like concentration, composition, temperature, or pH. Morphologies include micelles and their structural evolution with addition of other bio- or synthetic surfactants, co-surfactants, proteins or phospholipids.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117298136","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}

{"title":"Electro-optic response of bipolar nematic liquid crystal confined in oblate spheroid","authors":"Chenjing Yang, Ran Chen, Leyun Feng, Rui Zhang, D. Chen","doi":"10.3389/frsfm.2022.1022077","DOIUrl":"https://doi.org/10.3389/frsfm.2022.1022077","url":null,"abstract":"Electro-optic response of liquid crystals (LCs) relies on the molecular reorientation of LCs under external electric field and is important for a wide spectrum of applications. Here, we uncover an interesting electro-optic response of 5CB nematic LC confined in an oblate spheroid and subjected to external electric field. Under the planar anchoring, the nematic LC spheroid adopts a bipolar structure with the bipolar axis laid in the horizontal film plane. When a threshold electric field EF, is applied, the bipolar structure reorients from the horizontal configuration (LC molecules align along long axis direction) to the vertical configuration (LC molecules align along short axis direction), involving the competition of elastic energy, surface anchoring energy and electric field energy. In contrast to bipolar nematic LC droplets, the vertical configuration does not relax to the low-energy horizontal configuration after removing E; we argue that is due to the oblate shape of the nematic LC spheroid, which traps the bipolar structure in a local energy minimum. We use continuum simulation to demonstrate the detailed response and the reorientation dynamics of bipolar nematic spheroids under E field, showing consistent results with the experiments and confirming the proposed switching mechanism. Nevertheless, the vertical configuration of the bipolar structure could relax to the low-energy horizontal configuration by thermal cycling. Our studies provide clear experimental results that show the characteristics of the electro-optic response of oblate LC spheroids, which have both fundamental and practical implications.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124582445","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}

{"title":"A perspective on the Langmuir adsorption model applied to molecular liquid crystals containing ions and nanoparticles","authors":"Y. Garbovskiy","doi":"10.3389/frsfm.2022.1079063","DOIUrl":"https://doi.org/10.3389/frsfm.2022.1079063","url":null,"abstract":"Electrical properties of molecular liquid crystals doped with nanomaterials have been extensively studied over the past two decades. In general, nanoparticles in liquid crystals can play a dual role acting as either ion capturing agents or ion generating objects. An interplay between ions and nanomaterials in liquid crystals can result in a great variety of nontrivial ionic effects. This perspective discusses the Langmuir adsorption model applied to describe ionic phenomena in molecular liquid crystals doped with nanoparticles. The applicability and limitations of this model are emphasized. Within a range of its applicability, the Langmuir adsorption model can be used to obtain a wealth of information about nanoparticle-induced ionic effects in molecular liquid crystals. In addition, this model also offers important improvements to standard experimental procedures for evaluation of electrical properties of advanced liquid crystal materials.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127018145","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}

{"title":"Interplay of temperature and calcium content in beta-casein solutions: From controlled self-aggregation of micelles in bulk to the design of stable foams","authors":"A. Fameau, Bérénice Houinsou Houssou, A. Riaublanc, F. Cousin","doi":"10.3389/frsfm.2022.1008965","DOIUrl":"https://doi.org/10.3389/frsfm.2022.1008965","url":null,"abstract":"We describe in this study the aggregation behaviour of β-casein micelles from milk in bulk aqueous solution as function of both temperature and calcium content, and its influence on the foaming properties, in order to test if the different aggregation states of β-casein makes possible the design of proteins-based thermoresponsive foams. First, we characterized the morphology of the self-assembled β-casein molecules in solution by coupling turbidity measurements, Dynamic Light Scattering and Small Angle Neutron Scattering. They self-organize into individual micelles at low temperature (20°C) whatever the calcium content, and transit in a reversible way into aggregates of micelles at large temperature in presence of calcium, with a threshold transition that depend both on temperature and calcium content. The micelles aggregation is driven by the calcium through association with serine phosphate groups localized on the hydrophilic part of the β-casein. In the micelles regime, we demonstrated that the addition of calcium tunes the aggregation number of unimers per micelle in the same way than an increase of temperature through a change of hydrophobic interactions. The hydrophilic chains of the corona are however in a good solvent and interact through excluded volume interactions, even when the β-casein micelles aggregates themselves. The internal molecular structure of the micelles is thus not modified by calcium bridges, which explains the complete reversibility of the aggregation process over temperature cycling. Second, we studied the foam stability versus time as a function of the temperature and calcium content by measuring the kinetic evolution of both the foam volume and the liquid fraction. Foams produced by solutions containing only β-casein micelles were stable in terms of foam volume on a timescale of 1 h at 20°C but drained quickly. However, foams become unstable when the temperature was increased above 20°C. In presence of calcium, the aggregation of β-casein micelles inside the foam liquid channels enabled to increase foam stability at larger temperature by acting as a cork, which slows down the drainage. The increase of foam stability by such aggregates is however not sufficient on the long term to allow the design of thermoresponsive foams.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124359234","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}

{"title":"Effects of network connectivity on viscoelastic relaxation in transient networks using experimental approach","authors":"T. Katashima, Ryota Kudo, Ryoya Onishi, Mitsuru Naito, S. Nagatoishi, K. Miyata, K. Tsumoto, U. Chung, T. Sakai","doi":"10.3389/frsfm.2022.1059156","DOIUrl":"https://doi.org/10.3389/frsfm.2022.1059156","url":null,"abstract":"The effect of network connectivity on viscoelastic relaxation in transient networks with well-defined structures (Tetra-PEG slime) was experimentally evaluated and compared to bond dissociation kinetics. To control the connectivity and discuss the pure effect precisely, we mixed the precursors in off-stoichiometric ratio. With decreasing network connectivity, the viscoelastic relaxation time accelerated and became shorter than the bond dissociation time. With increasing polymer concentration, the connectivity at which the viscoelastic relaxation time matched the dissociation time shifted to the high-connectivity region. The dependence of viscoelastic relaxation on connectivity can be adequately explained within the framework of the lifetime of a backbone. The backbone has numerous breakage points in low-connectivity region nearby the gelation point, resulting in a shorter lifetime than the dissociation time. However, the Rubinstein-Semenov model based on backbone relaxation does not predict the concentration dependence, suggesting that the formation of the network in the dilute/semi-dilute region deviates from a random branching process. These findings provide a crucial foundation for the molecular comprehension of transient network materials.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126935546","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}

{"title":"The dynamics of single-to-multi layer transition in bacterial swarms","authors":"Iago Grobas, Munehiro Asally, M. Polin","doi":"10.3389/frsfm.2022.936779","DOIUrl":"https://doi.org/10.3389/frsfm.2022.936779","url":null,"abstract":"Wet self-propelled rods at high densities can exhibit a state of mesoscale turbulence: a disordered lattice of vortices with chaotic dynamics and a characteristic length scale. Such a state is commonly studied by a two-dimensional continuum model. However, less is known about the dynamic behaviour of self-propelled rods in three- or quasi-two- dimensions, which can be found in biological systems, for example, during the formation of bacterial aggregates and biofilms. In this study, we characterised the formation of multi-layered islands in a monolayer of swarming cells using the rod-shaped bacteria B. subtilis as a model system. We focused on how bacteria form multiple layers and how the presence of stress affects the multiple layer formation. Following our previous study where we reported that the initiation of the multilayer formation can be accounted by the framework of motility-induced phase separation (MIPS), this study analysed how this phase separation is impacted by the presence of stress, specifically under the exposure to a gradient of antibiotic. The analyses show that in the presence of an antibiotic gradient, the multi-layer formation happens by a nucleation and growth of well-defined multilayered clusters instead of by the uncontrolled emergence of the multilayer, resembling the traditional thermodynamic processes of binodal and spinodal decomposition respectively. Finally, the multilayer gives place to waves of bacteria that can travel towards high concentrations of antibiotics and that resemble travelling waves predicted by simulations of mixtures of passive and active particles.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128524621","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}

{"title":"Liquid crystal-based actuators","authors":"A. Gruzdenko, I. Dierking","doi":"10.3389/frsfm.2022.1052037","DOIUrl":"https://doi.org/10.3389/frsfm.2022.1052037","url":null,"abstract":"Liquid crystal polymer networks (LCNs) have a great potential in soft actuator technologies. In contrast to other materials, LCNs offer a wide range of external stimuli which can trigger their actuation. These are for example based on changes of temperature, photo-induced or via the application of electric fields. We here discuss the main LCN actuation mechanisms and classify them into several groups based on the used stimulus. Specific recent examples are provided for liquid crystal actuators and several general applications of such materials in connection to actuation mechanisms are exemplary outlined.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121541245","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}

{"title":"Untangling effects of proteins as stabilizers for foam films","authors":"Kevin Gräff, S. Stock, Luca Mirau, Sabine Bürger, Larissa Braun, Annika R Völp, N. Willenbacher, R. von Klitzing","doi":"10.3389/frsfm.2022.1035377","DOIUrl":"https://doi.org/10.3389/frsfm.2022.1035377","url":null,"abstract":"Foam film’s properties have a high impact on the properties of the macroscopic foams. This work focusses on protein stabilized foam films. The direct comparison of three different proteins with a concentration normalized to the protein surface enables to distinguish between electrostatic, steric and network stabilization effects. In order to untangle those effects, we study and compare two globular proteins (β − lactoglobulin, BLG, and bovine serum albumin, BSA) and a disordered, flexible protein (whole casein, CN) at low ionic strengths with varying solution pH. Image intensity measurement as a recently developed image analysis method in this field allows to record spatially resolved disjoining pressure isotherms in a Thin Film Pressure Balance (TFPB). This reveals insights into the structure formation in inhomogeneous protein films. As a novel method we introduce tracking inhomogeneities (features) which enables the measurement of interfacial mobility and stiffness of foam films. Around the isoelectric point (IEP), Newton Black Films (NBF) form which are stable for the globular proteins while they are unstable for the disordered flexible one. This difference in film stability is explained by different characteristics of the network structures which is supported by findings in the bulk and at the surface of the respective protein solutions.","PeriodicalId":409762,"journal":{"name":"Frontiers in Soft Matter","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115769054","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}