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Brouzet, Christophe
Publications (4 of 4) Show all publications
Brouzet, C., Mittal, N., Lundell, F. & Söderberg, D. (2019). Characterizing the Orientational and Network Dynamics of Polydisperse Nanofibers on the Nanoscale. Macromolecules, 52(6), 2286-2295
Open this publication in new window or tab >>Characterizing the Orientational and Network Dynamics of Polydisperse Nanofibers on the Nanoscale
2019 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 6, p. 2286-2295Article in journal (Refereed) Published
Abstract [en]

Polydisperse fiber networks are the basis of many natural and manufactured structures, ranging from high-performance biobased materials to components of living cells and tissues. The formation and behavior of such networks are given by fiber properties such as length and stiffness as well as the number density and fiber-fiber interactions. Studies of fiber network behavior, such as connectivity or rigidity thresholds, typically assume monodisperse fiber lengths and isotropic fiber orientation distributions, specifically for nano scale fibers, where the methods providing time-resolved measurements are limited. Using birefringence measurements in a microfluidic flow-focusing channel combined with a flow stop procedure, we here propose a methodology allowing investigations of length-dependent rotational dynamics of nanoscale polydisperse fiber suspensions, including the effects of initial nonisotropic orientation distributions. Transition from rotational mobility to rigidity at entanglement thresholds is specifically addressed for a number of nanocellulose suspensions, which are used as model nanofiber systems. The results show that the proposed method allows the characterization of the subtle interplay between Brownian diffusion and nanoparticle alignment on network dynamics.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-246216 (URN)10.1021/acs.macromol.8b02714 (DOI)000462950300007 ()2-s2.0-85062860050 (Scopus ID)
Note

QC 20190318. QC 20191031

Available from: 2019-03-17 Created: 2019-03-17 Last updated: 2019-10-31Bibliographically approved
Gowda, K. V., Brouzet, C., Lefranc, T., Söderberg, D. & Lundell, F. (2019). Effective interfacial tension in flow-focusing of colloidal dispersions: 3-D numerical simulations and experiments. Journal of Fluid Mechanics, 876, 1052-1076, Article ID PII S0022112019005664.
Open this publication in new window or tab >>Effective interfacial tension in flow-focusing of colloidal dispersions: 3-D numerical simulations and experiments
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2019 (English)In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 876, p. 1052-1076, article id PII S0022112019005664Article in journal (Refereed) Published
Abstract [en]

An interface between two miscible fluids is transient, existing as a non-equilibrium state before complete molecular mixing is reached. However, during the existence of such an interface, which typically occurs at relatively short time scales, composition gradients at the boundary between the two liquids cause stresses effectively mimicking an interfacial tension. Here, we combine numerical modelling and experiments to study the influence of an effective interfacial tension between a colloidal fibre dispersion and its own solvent on the flow in a microfluidic system. In a flow-focusing channel, the dispersion is injected as core flow that is hydrodynamically focused by its solvent as sheath flows. This leads to the formation of a long fluid thread, which is characterized in three dimensions using optical coherence tomography and simulated using a volume of fluid method. The simulated flow and thread geometries very closely reproduce the experimental results in terms of thread topology and velocity flow fields. By varying the interfacial tension numerically, we show that it controls the thread development, which can be described by an effective capillary number. Furthermore, we demonstrate that the applied methodology provide the means to measure the ultra-low but dynamically highly significant effective interfacial tension.

Place, publisher, year, edition, pages
CAMBRIDGE UNIV PRESS, 2019
Keywords
colloids, capillary flows, multiphase flow
National Category
Fluid Mechanics and Acoustics
Research subject
Physics, Material and Nano Physics
Identifiers
urn:nbn:se:kth:diva-261291 (URN)10.1017/jfm.2019.566 (DOI)000486462700001 ()2-s2.0-85070832669 (Scopus ID)
Note

QC 20191008

Available from: 2019-10-08 Created: 2019-10-08 Last updated: 2019-11-26Bibliographically approved
Mittal, N., Ansari, F., Gowda, K. V., Brouzet, C., Chen, P., Larsson, P. T., . . . Söderberg, D. (2018). Multiscale Control of Nanocellulose Assembly: Transferring Remarkable Nanoscale Fibril Mechanics to Macroscale Fibers. ACS Nano, 12(7), 6378-6388
Open this publication in new window or tab >>Multiscale Control of Nanocellulose Assembly: Transferring Remarkable Nanoscale Fibril Mechanics to Macroscale Fibers
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2018 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 7, p. 6378-6388Article in journal (Refereed) Published
Abstract [en]

Nanoscale building blocks of many materials exhibit extraordinary mechanical properties due to their defect-free molecular structure. Translation of these high mechanical properties to macroscopic materials represents a difficult materials engineering challenge due to the necessity to organize these building blocks into multiscale patterns and mitigate defects emerging at larger scales. Cellulose nanofibrils (CNFs), the most abundant structural element in living systems, has impressively high strength and stiffness, but natural or artificial cellulose composites are 3-15 times weaker than the CNFs. Here, we report the flow-assisted organization of CNFs into macroscale fibers with nearly perfect unidirectional alignment. Efficient stress transfer from macroscale to individual CNF due to cross-linking and high degree of order enables their Young's modulus to reach up to 86 GPa and a tensile strength of 1.57 GPa, exceeding the mechanical properties of known natural or synthetic biopolymeric materials. The specific strength of our CNF fibers engineered at multiscale also exceeds that of metals, alloys, and glass fibers, enhancing the potential of sustainable lightweight high-performance materials with multiscale self-organization.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
bio-based materials, selforganization, mechanical properties, microfluidics, cellulose nanofibrils, nanocompositesbio-based materials, selforganization, mechanical properties, microfluidics, cellulose nanofibrils, nanocomposites
National Category
Engineering and Technology
Research subject
Engineering Mechanics; Fibre and Polymer Science; Physics
Identifiers
urn:nbn:se:kth:diva-229288 (URN)10.1021/acsnano.8b01084 (DOI)000440505000004 ()29741364 (PubMedID)2-s2.0-85049865626 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20180608

Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2019-10-16Bibliographically approved
Brouzet, C., Mittal, N., Söderberg, D. & Lundell, F. (2018). Size-Dependent Orientational Dynamics of Brownian Nanorods. ACS Macro Letters, 7(8), 1022-1027
Open this publication in new window or tab >>Size-Dependent Orientational Dynamics of Brownian Nanorods
2018 (English)In: ACS Macro Letters, E-ISSN 2161-1653, Vol. 7, no 8, p. 1022-1027Article in journal (Refereed) Published
Abstract [en]

Successful assembly of suspended nanoscale rod-like particles depends on fundamental phenomena controlling rotational and translational diffusion. Despite the significant developments in fluidic fabrication of nanostructured materials, the ability to quantify the dynamics in processing systems remains challenging. Here we demonstrate an experimental method for characterization of the orientation dynamics of nanorod suspensions in assembly flows using orientation relaxation. This relaxation, measured by birefringence and obtained after rapidly stopping the flow, is deconvoluted with an inverse Laplace transform to extract a length distribution of aligned nanorods. The methodology is illustrated using nanocelluloses as model systems, where the coupling of rotational diffusion coefficients to particle size distributions as well as flow-induced orientation mechanisms are elucidated. 

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-233806 (URN)10.1021/acsmacrolett.8b00487 (DOI)000442707200022 ()2-s2.0-85052098273 (Scopus ID)
Note

QC 20180903

Available from: 2018-08-28 Created: 2018-08-28 Last updated: 2019-02-07Bibliographically approved
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