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Prof.
Khoa V. Le
Tokyo University of Science
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Speech Title:
Self-Assembled Supramolecular Chromonic Dyes: Mechanical Robustness and Underwater Adhesion
Abstract: We report a functional material system that leverages the supramolecular self-assembly of lyotropic chromonic dyes to achieve exceptional mechanical robustness and dynamic responsiveness. Featuring hydrophobic aromatic cores surrounded by hydrophilic ionic groups, these chromonic molecules self-assemble into anisotropic columnar aggregates in aqueous environments. When integrated into a polymeric matrix, the chromonic assemblies act as dynamic, reversible physical cross-links. This supramolecular architecture provides efficient energy dissipation and stress relaxation, resulting in a soft network with high fracture toughness, mechanical durability, and stretchability.
Beyond its core mechanical strength, the dynamic nature and structural order of the supramolecular chromonic cross-links grant the material stable underwater surface adhesion without requiring chemical adhesives. Tensile tests in water demonstrate adhesion strengths on the order of tens of kPa across various plastic substrates, enabling the effective capture and immobilization of microplastic particles from aqueous media. Combining full water-processability, structural anisotropy, and superior mechanical toughness, this supramolecular chromonic dye system demonstrates how molecular self-assembly can be harnessed to design high-performance functional materials for advanced soft matter engineering and environmental applications.
Biography:
Dr. Khoa V. Le received his Ph.D. in Organic
Materials Engineering from the Institute of Science Tokyo (formerly
Tokyo Institute of Technology),
Japan, in 2011. In 2015, he joined the Tokyo University of Science,
where he is currently an Associate Professor.His research interests
include electro-optic effects in liquid crystals and molecular
interactions in lyotropic systems. More recently, his work has focused
on water-based polymeric materials, combining lyotropic liquid crystals
with hydrogels to achieve novel functionalities such as enhanced
toughness and adhesiveness. His research aims to develop practical
applications in biological alternatives, bio-adhesives, and microplastic
capture materials.Dr. Le has an extensive publication record built on
strong international collaborations, with papers featured in
prestigious, top-tier journals such as Nature Communications, PNAS, and
Advanced Materials. His contributions have been widely recognized by
academic societies, including multiple awards
from the Japanese Liquid Crystals Society. Additionally, he serves as a
Regional Editor for Molecular Crystals and Liquid Crystals, a
well-established journal published by Taylor & Francis, UK. |
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Professor Dr. Eng. Jesús Toribio
University of Salamanca (USAL) |
Speech Title:
Fatigue, Fracture & Structural Integrity in Cold-Drawn Pearlitic Steel Wires
as Hierarchically-Structured Nano-Composite Materials:
A Tribute to Fray Luis de León, Miguel de Cervantes,
Maurits Cornelis Escher and Johann Sebastian Bach
Abstract: Cold drawn
pearlitic steel wires posses an inherent hierarchical microstructure
consisting of pearlitic colonies (first microstructural level) and
pearlite (ferrite/Fe and cementite/Fe3C) lamellae (second
microstructural level), so that they can be considered as
nano-composites from the materials science & engineering point of view.
Such a microstructure evolves during the manufacturing process by cold
drawing towards a preferential orientation aligned in the drawing (wire
axis) direction, so that these materials acquire microstructural
anisotropy that influences their posterior fatigue, fracture &
structural integrity behaviour at different scales, and a multi-scale
approach to the problem can be established, formulating the innovative
concepts of macro-, micro- and nano-structural integrity. This keynote
presentation deals with fatigue, fracture & structural integrity
behaviour of progressively cold-drawn pearlitic steel wires on the basis
of their microstructural evolution during manufacturing by multi-step
cold drawing. In the matter of fatigue, it is seen that the afore-said
microstructural orientation influences the fatigue crack growth, with
local roughness and micro-deflections that produce a tortuous fatigue
crack path, the angle of micro-deflections depending of the
microstructural orientation angle. With regard to fracture & structural
integrity, failure analysis of notched specimens of very different
geometries (very distinct degree of constraint) shows the necessity of
both microstructural orientation and triaxiality level to obtain
fracture path deflection, while in cracked specimens anisotropic
fracture takes place, allowing the definition of a sort of directional
toughness in the material. All these phenomena are a consequence of the
microstructural orientation generated in the material during
manufacturing by cold drawing. The paper establishes an analogy with the
literature of the Spanish writers Fray Luis de León and Miguel de
Cervantes and the Dutch painter Maurits Cornelis Escher (through the
alternate distribution of ferrite/cementite lamellae) and the German
composer Johann Sebastian Bach (through the hierarchical structure of
his music).
Biography:
Professor Jesús Toribio graduated in Civil Engineering in 1982 and then
in Mathematics in 1986. In 1987 he was awarded his PhD in the
Polytechnic University of Madrid (UPM) and turned into Associate
Professor in that Institution. In 1992 he became Full Professor and Head
of the Materials Science Department of the University of La Coruña (at
the age of 32, thus being the youngest Full Professor in the area of
Materials Science in Spain). In 2000 he moved to the University of
Salamanca (USAL) where is currently Full Professor of Materials Science
& Engineering and Head of the Fracture & Structural Integrity Research
Group (FSIRG) of that Institution.
His research work is mainly concerned with fatigue and fracture
mechanics, environmentally assisted cracking, stress corrosion cracking
and hydrogen embrittlement/degradation/damage of metals and alloys
(mainly cold drawn pearlitic steel wires for civil engineering and
austenitic stainless steels for nuclear engineering and energy
applications), covering theoretical, computational and experimental
aspects. He actively participates in International Scientific
Conferences, very often being a member of the International Advisory
Committee, organising Special Sessions and Symposia, being Session
Chairman or specially delivering Plenary/Keynote/Invited Lectures.
Professor Dr. Jesús Toribio has published more than 600 scientific
papers, most of them in international books and journals.
He is the Chairman of the Technical Committee 10 (TC10): Environmentally
Assisted Cracking & Hydrogen Embrittlement of the European Structural
Integrity Society (ESIS) and has been Director (2013-2017) of the
International Congress of Fracture-The World Academy of Structural
Integrity (ICF-WASI), being responsible of launching the Ibero-American
Academy of Structural Integrity (IA2SI). Prof. Toribio has been awarded
a variety of scientific research prizes and awards including: (i) UPM
Young Scientist Award of the Polytechnic University of Madrid; (ii)
METROTEC Award for the best Technological Research Project; (iii) Honour
Medal of the Spanish Group of Fracture (GEF/SEIE) in recognition of his
research achievements in the field of fracture mechanics; (iv) Fellow of
the Wessex Institute of Technology (WIT) in recognition of leadership
and outstanding work in engineering sciences; (v) Top Reviewer 2011 in
recognition of an outstanding contribution to the quality of the
Elsevier International Journal Engineering Fracture Mechanics; (vi)
Fellow of the European Structural Society (ESIS Fellow) for his
outstanding contributions to the art, science, teaching or practice of
fracture mechanics and his service to the society; (vii) Honorary Member
of the Italian Group of Fracture (IGF) in acknowledgement and
appreciation of his outstanding achievements in the research field of
fracture mechanics; (viii) Best Paper and Presentation Award in the
International Conference on Energy Materials and Applications (ICEMA
2017) held in 2017 in Hiroshima, Japan, with a paper entitled: Numerical
Simulation of Hydrogen Diffusion in the Pressure Vessel Wall of a
WWER-440 Reactor; (ix) María de Maeztu Scientific Award of the
University of Salamanca (800th anniversary during 2018) in recognition
of academic trajectory and excellence in scientific and technological
research; (x) Scientific Merit Award of the Portuguese Group of Fracture
(PGF) in recognition of scientific contributions during his career.
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