Dr. Chung-Yuan Mou
From the Special Topic of
According to our Special Topic on mesoporous materials,
Dr. Chung-Yuan Mou's work ranks at #5 by number of papers,
with 68 qualifying papers cited a total of 1,003 times. Dr.
Mou's record in
Science IndicatorsSM from
Reuters includes 176 papers cited a total of 2,021
times between January 1, 1998 and February 29, 2008, the
bulk of which are found in the fields of Chemistry and
Dr. Mou is a Professor in the Department of Chemistry and
the Center of Condensed Matter Science at National Taiwan
University in Taipei.
In the interview below, he talks with
ScienceWatch.com about his highly cited research on
Please tell us a little about your
educational and research background.
I did my undergraduate study in chemistry at National Taiwan University. In
graduate school, I was trained in theoretical chemistry; my Ph.D. thesis
was on nucleation theory (Washington University in St Louis, 1976). After
postdoctoral researches, I returned to teach in the department of chemistry
of National Taiwan University in 1978, and have been here ever since.
Until 1992, my research activities were mainly in the statistical mechanics
of electrolyte solution and non-equilibrium systems. In the early 1990s, I
started seriously going into experimental materials chemistry, first in C60
and carbon nanotubes, and later in mesoporous silica materials.
What drew your interest to materials science, and
in particular meso/nanoporous materials?
My theoretical background may seem to be an unusual starting point for
getting into materials science. Actually in the late 1980s, I was paying
close attention to the physical chemistry of self-assembly of amphiphiles
in solution, both in theoretical and experimental sides. So when the first
synthesis of MCM-41 by surfactant-templating was reported by Mobile
researchers, I was able to move into the field with good understanding of
its physical chemistry. Besides, at the time I was teaching undergraduate
experimental physical chemistry course and writing a textbook for it. That
helps me to learn many experimental techniques.
To me, mesoporous silica materials are an ideal playground for materials
synthesis with wide possibilities of structure and morphology control and
many chemical applications. My first paper on mesoporous silica was
published in Science in 1996 (Lin HP, Mou CY,
"'Tubules-within-a-tubule' hierarchical order of mesoporous molecular
sieves in MCM-41," Science 273: 765-68, 9 August 1996). It
is the first work on hierarchical organization of mesoporous silica from
the point of view of soft matter physics. The success of that first paper
led to many other ideas and I gradually gave up on theoretical work and
focused on mesoporous materials.
In our analysis, one of your highly cited papers
is the 1998 Chemistry of Materials paper, "Hierarchical order
in hollow spheres of mesoporous silicates," (Lin HP, Cheng YR, Mou CY,
10: 3772+, December 1998). Would you walk our readers through this
paper—its aims, findings, and significance?
My 1998 Chemistry of Materials paper reports a morphosynthesis of
mesoporous silica MCM-41 in an intricate morphology of
pillar-within-sphere. Its micron scale structures consist of hollow spheres
with a pillar, fork, or cross inside. This paper together with my 1996
science paper gave two early examples of building hierarchical structures
of mesoporous silica. Also, they are the first two papers bringing together
ideas in sol-gel synthesis and soft-matter physics to mesoporous materials.
We found there is organization in the micrometer scale on top of the
nanometer structural order from self-assembly. The micron scale
organization comes about through transformation of mesophases.
Understanding hierarchical organization of matter is important for biomimic
strategies of fabricating materials.
Anyway, the pillar-within-sphere organization is distinctly nature-like, a
bit like the frustal of radiolaria and diatoms. The structure is beautiful
in my view. Maybe one day, someone will be able to make intricate silica
structures like diatoms in the laboratory—that would be most
There are practical implications too. By learning to control the morphology
during synthesis of mesoporous silica through understanding its physics of
self-assembly, we later developed other morphologies such as thin films
with vertical channels (for catalysis support) and mesoporous silica
nanoparticles (for biomedical applications).
Many of your papers in our analysis concern
supercooled water confined in nanoporous silica. Would you talk a
little bit about this aspect of your work?
Liquid water is a complex fluid with many abnormal properties not yet well
understood. Its anomaly becomes more prominent in supercooled state and
there are hints of thermodynamic singularity below –40°C.
However, ice nucleation would take over at about –35°C for bulk
materials are an ideal playground for materials
synthesis with wide possibilities of structure and
morphology control and many chemical
In 2002, I discussed the possibility of avoiding freezing using
mesopore-confined water with Prof. Sow-Hsin Chen of MIT, a leading expert
in neutron scattering. Soon this was realized with specially designed
mesoporous silica with small pores, and suddenly a whole range
thermodynamic state of water became accessible.
Since then, a series of publications (including four PNAS and one
Physical Review Letters paper) with Chen and Francesco Mallamace
(University of Messina) followed, reporting many significant discoveries
about supercooled water. We found a fragile-to-strong dynamical transition
at low temperature. Recently, for the first time we discovered a density
minimum of D2O at 210 K by SANS, in addition to the well-known density
maximum. (Liu D, et al., "Observation of the density minimum in
deeply supercooled confined water," PNAS 104: 9570-4, 5 June
2007). This discovery is highly significant in our fundamental
understandings about the structure of water.
This whole series of works have attracted a lot of attention from
physicists, chemists, and biologists. Our 2005 Physical Review
Letters paper (Liu L, et al., "Pressure dependence of
fragile-to-strong transition and a possible second critical point in
supercooled confined water," Phys. Rev. Lett. 95: Art. no.
117802, 9 September 2005) has been highly cited, and was recently listed in
the Research Front rankings of Essential Science Indicators.
Are there any other papers, regardless of
citations, you would like to highlight and discuss their
Our 2005 Chemistry of Materials paper on "Well-ordered mesoporous
silica nanoparticles (MSN) as cell markers" (Lin YS, et al., Chem.
Mater. 17:4570-3, 6 September 2005) is the first report of making
well-suspended nanoparticles of mesoporous silica with a fluorescence agent
as the cell marker. This work has led to developing MSN as a
multi-functional, contrast-enhancing, and drug-delivery agent, which
combines organic/inorganic and diagnostic/therapeutic components within a
nanoscaled delivery agent. The pores may be used for delivering drugs,
enzymes, DNA, or RNA.
At present, many types of nanoparticles, such as quantum dots and metals,
are being developed as cell-tracking/delivery agents. However, metals and
Q-dots are toxic. Our silica materials, however, are quite safe. Therefore,
we envision its development for clinical use in cell tracking, drug
delivery, and gene therapy. We are making long-term collaborations between
biologists, clinical doctors, and chemists. It is challenging.
What are the practical applications (or potential
applications) of these materials?
The field of mesoporous materials is expanding into many major
applications. These include catalyst support, biomedical tracking/delivery
platform, and as an adsorption/separation agent. I foresee many new
applications in the years to come.
What should the "take-away lesson" be about your work?
Materials science is truly interdisciplinary. Scientists from different
backgrounds can make good contributions. However, there is a need to
integrate "vertically," particularly in nanomaterials. Too often, we see
fabrication of intricate materials without the follow-up of applications.
Using mesopore as a nano-reactor, the selectivity and activities of many
reactions can be changed and exploited. The physics of small systems can be
studied creatively by confining matter within. Hierarchical materials of a
mesoporous nature can be built to satisfy various applications in
biomedicine and engineering.
Department of Chemistry
Center of Condensed Matter Science
National Taiwan University
Mou's most-cited paper with 95
cites to date:
Lin HP, Cheng YR, Mou CY, "Hierarchical order in hollow
spheres of mesoporous silicates," Chem. Mater.
10(12): 3772-+, December 1998. Source:
Essential Science Indicators from
Keywords: mesoporous silicates,
mesoporous materials, materials synthesis, supercooled water, cell
marker, drug delivery, gene therapy applications.