Glass transition of soft colloids

We explore the glassy dynamics of soft colloids using microgels and charged particles interacting by steric and screened Coulomb interactions, respectively. In the supercooled regime, the structural relaxation time τα of both systems grows steeply with volume fraction, reminiscent of the behavior of colloidal hard spheres. Computer simulations confirm that the growth of τα on approaching the glass transition is independent of particle softness. By contrast, softness becomes relevant at very large packing fractions when the system falls out of equilibrium. In this nonequilibrium regime, τα depends surprisingly weakly on packing fraction, and time correlation functions exhibit a compressed exponential decay consistent with stress-driven relaxation. The transition to this novel regime coincides with the onset of an anomalous decrease in local order with increasing density typical of ultrasoft systems. We propose that these peculiar dynamics results from the combination of the nonequilibrium aging dynamics expected in the glassy state and the tendency of colloids interacting through soft potentials to refluidize at high packing fractions

How Tuning Interfaces Impacts the Dynamics and Structure of Polymer Nanocomposites Simultaneously

Fundamental understanding of macroscopic properties of polymer nanocomposites (PNCs) remains difficult due to the complex interplay of microscopic dynamics and structure, namely interfacial layer relaxations and three-dimensional nanoparticle arrangements. The effect of surface modification by alkyl methoxysilanes at different grafting densities has been studied in PNCs made of poly(2-vinylpyridine) and spherical 20 nm silica nanoparticles (NPs). The segmental dynamics has been probed by broadband dielectric spectroscopy, and the filler structure by small-angle X-ray scattering and reverse Monte Carlo simulations. By combining the particle configurations with the interfacial layer properties, it is shown how surface modification tunes the attractive polymer-particle interactions: bare NPs slow down the polymer interfacial layer dynamics over a thickness of ca. 5 nm, while grafting screens these interactions. Our analysis of interparticle spacing and segmental dynamics provides unprecedented insight into the effect of surface modification on the main characteristics of PNCs: particle interactions and polymer interfacial layers

Concepts for the Development of Person-Centered, Digitally Enabled, Artificial Intelligence–Assisted ARIA Care Pathways (ARIA 2024)

Funding Information: This work has received funding from ARIA (Allergic Rhinitis and its Impact of Asthma); CATALYSE (Climate Action To Advance HeaLthY Societies in Europe), the European Union\u2019s Horizon Europe research and innovation program under grant agreement no. 101057131; FRAUNHOFER Institute for Translational Medicine and Pharmacology (ITMP), Immunology and Allergology, Berlin, Germany; University of Porto, Portugal; and MASK-air, which has been supported by EU grants (Impact of air Pollution on Asthma and Rhinitis [POLLAR] project of the European Institute of Innovation and Technology Health; Structural and Development Funds, R\u00E9gion Languedoc Roussillon and Provence-Alpes-C\u00F4te d\u2019Azur; Twinning, European Innovation Partnership on Active and Healthy Ageing, DG Sant\u00E9 and DG Connect); educational grants from Mylan-Viatris, Allergologisk Laboratorium K\u00F8benhavn, GlaxoSmithKline, Novartis, Stallerg\u00E8nes-Greer, and Noucor; and funding from Breathing Together Onlus Association (Associazione Respiriamo Insieme Onlus), Italy; Esp\u00EDritu Santo University, Samborond\u00F3n, Ecuador; Finnish Anti-Tuberculosis Association Foundation and Tampere Tuberculosis Foundation; GA 2 LEN; German Allergy Society AeDA (\u00C4rzteverband Deutscher Allergologen); IPOKRaTES (International Postgraduate Organization for Knowledge transfer, Research and Teaching Excellent Students) Lithuania Fund; Polish Society of Allergology (POLSKIE TOWARZYSTWO ALLERGOLOGICZNE); and University of Li\u00E8ge, Belgium. Funding Information: Conflicts of interest: J. Bousquet reports personal fees from Cipla, Menarini, Mylan, Novartis, Purina, Sanofi-Aventis, Teva, Noucor, other from KYomed-Innov, and other from Mask-air-SAS, outside the submitted work. M. Blaiss reports personal fees from Sanofi, personal fees from Regeneron, personal fees from ALK, personal fees from Merck, personal fees from AstraZeneca, personal fees from GSK, personal fees from Prollergy, personal fees from Lanier Biotherapeutics, and nonfinancial support from Bryn Phama, outside the submitted work. J. Lity\u0144ska reports personal fees from Evidence Prime Sp. z o.o., outside the submitted work. T. Iinuma reports grants from Sanofi, outside the submitted work. P. Tantilipikorn reports grants from Abbott, other from GSK, and other from Sanofi Aventis, outside the submitted work. T. Haahtela reports personal fees from Orion Pharma, outside the submitted work. Publisher Copyright: © 2024 The AuthorsThe traditional healthcare model is focused on diseases (medicine and natural science) and does not acknowledge patients’ resources and abilities to be experts in their own lives based on their lived experiences. Improving healthcare safety, quality, and coordination, as well as quality of life, is an important aim in the care of patients with chronic conditions. Person-centered care needs to ensure that people's values and preferences guide clinical decisions. This paper reviews current knowledge to develop (1) digital care pathways for rhinitis and asthma multimorbidity and (2) digitally enabled, person-centered care.1 It combines all relevant research evidence, including the so-called real-world evidence, with the ultimate goal to develop digitally enabled, patient-centered care. The paper includes (1) Allergic Rhinitis and its Impact on Asthma (ARIA), a 2-decade journey, (2) Grading of Recommendations, Assessment, Development and Evaluation (GRADE), the evidence-based model of guidelines in airway diseases, (3) mHealth impact on airway diseases, (4) From guidelines to digital care pathways, (5) Embedding Planetary Health, (6) Novel classification of rhinitis and asthma, (7) Embedding real-life data with population-based studies, (8) The ARIA-EAACI (European Academy of Allergy and Clinical Immunology) strategy for the management of airway diseases using digital biomarkers, (9) Artificial intelligence, (10) The development of digitally enabled, ARIA person-centered care, and (11) The political agenda. The ultimate goal is to propose ARIA 2024 guidelines centered around the patient to make them more applicable and sustainable.proofinpres

Textural control of ionosilicas by ionic liquid templating

International audienceIonic liquids were used as templates for the synthesis of mesoporous ionosilica phases. The textures of the formed solids can be efficiently controlled by adjusting the quantity of the IL and the length of the alkyl chain of the IL

Exploiting the lower disorder-to-order temperature in polystyrene-<i>b</i>-poly(<i>n-</i>butyl acrylate)-<i>b</i>-polystyrene triblock copolymers to increase their flow resistance at high temperature

This work focuses on the temperature-dependent structural and rheological characterization of polystyrene-b-poly(n-butyl acrylate)-b-polystyrene triblock copolymers (PS-b-PnBA-b-PS) in the melt and, in particular, on their ability to show a lower disorder-to-order temperature (LDOT). To this aim, copolymers of varying block lengths, but keeping the PnBA block as a major component, were synthesized. Small-angle x-ray scattering revealed that the copolymers with short PS blocks (∼10 kg/mol) approach an LDOT but do not cross it. At room temperature, these copolymers exhibit higher moduli compared to a PnBA homopolymer due to the reinforcing effect of the PS but are flowing at temperatures above the glass transition of the PS. Increasing the PS and PnBA block length, to keep the same PS fraction, induces more profound changes in the structural and viscoelastic behaviors. Such a copolymer crosses the LDOT, leading to a microphase-separated and ordered state at high temperature. Contrary to the copolymers with short PS blocks, the flow regime was not reached, even at temperatures well above the glass transition of the PS. Instead, a low-frequency plateau was observed in rheology, showing the increased lifetime of the microphase-separated PS domains. ABA triblock copolymers exhibiting an LDOT behavior could, thus, be of interest for the design of thermoplastic elastomers or pressure-sensitive adhesives that can resist the flow at high temperatures

Flow-induced crystallization of a multiblock copolymer under large amplitude oscillatory shear: Experiments and modeling

International audienc

Nano-porous structures via self-assembly of amphiphilic triblock copolymers: influence of solvent and molecular weight

International audienceControl of film structures made from a polystyrene-polystyrene sodium sulfonate-polystyrene (PS-PNaSS-PS) copolymer micellar solution is investigated in a THF/water mixture. Four different copolymers (varying molecular weights) are synthesised via RAFT (Reversible Addition Fragmentation chain Transfer) polymerisation. Depending on parameters such as copolymer molecular weight, solvent composition and copolymer concentration, the PS-PNaSS-PS triblock self-assembles into different morphologies in solution and dry state. The effect of each parameter is investigated using characterization techniques such as AFM, TEM, Cryo-TEM, SEM and SAXS. The morphologies obtained for PS-PNaSS-PS are found to be extremely sensitive when the water content of the micellar solution is low. Among the structures observed, a highly ordered nano-porous film is obtained using a PS10k-PNaSS6k-PS10k triblock copolymer solution containing 3.0 wt% of water. This micellar solution is used to prepare a porous membrane for filtration applications. Pure water filtration data suggest a pore size in the range of ultrafiltration, making these membranes attractive for applications in the food industry, for bacteria, virus and protein removal

Influence of the Graft Length on Nanocomposite Structure and Interfacial Dynamics

Both the dispersion state of nanoparticles (NPs) within polymer nanocomposites (PNCs) and the dynamical state of the polymer altered by the presence of the NP/polymer interfaces have a strong impact on the macroscopic properties of PNCs. In particular, mechanical properties are strongly affected by percolation of hard phases, which may be NP networks, dynamically modified polymer regions, or combinations of both. In this article, the impact on dispersion and dynamics of surface modification of the NPs by short monomethoxysilanes with eight carbons in the alkyl part (C8) is studied. As a function of grafting density and particle content, polymer dynamics is followed by broadband dielectric spectroscopy and analyzed by an interfacial layer model, whereas the particle dispersion is investigated by small-angle X-ray scattering and analyzed by reverse Monte Carlo simulations. NP dispersions are found to be destabilized only at the highest grafting. The interfacial layer formalism allows the clear identification of the volume fraction of interfacial polymer, with its characteristic time. The strongest dynamical slow-down in the polymer is found for unmodified NPs, while grafting weakens this effect progressively. The combination of all three techniques enables a unique measurement of the true thickness of the interfacial layer, which is ca. 5 nm. Finally, the comparison between longer (C18) and shorter (C8) grafts provides unprecedented insight into the efficacy and tunability of surface modification. It is shown that C8-grafting allows for a more progressive tuning, which goes beyond a pure mass effect