Chemical Engineering July 2016 - 13

A glass for all colors
C
olloidal glasses develop structural
color through constructive interference.
The color can be tuned by adjusting
interparticle distance, making
the colloidal glasses attractive for use as color
pigments for use in coatings, displays, colorimetric
sensors and optical barcodes. While
colloidal crystals exhibit brilliant color with
wavelengths that are strongly angle-dependent,
colloidal glasses with only short-range
order provide dim, but angle-independent
structural color due to their isotropic nature.
There are a number of ways to prepare colloidal
glasses, but it is difficult to produce red
color with them because a cavity-like mode
from individual particles yields strong backscattering
in blue, overwhelming the resonance
in red from the glassy colloidal array.
To develop red structural color, the optical
length within particles must be shortened.
Now a group from the Dept. of Chemical
and Biomolecular Engineering at the Korea
Advanced Institute of Science and Technology
(KAIST; Daejeon, South Korea; www.
kaist.ac.kr), led by professor Shin-Hyun Kim,
P
L
olylactic acid (PLA) is a versatile biopolymer,
but its applications are
somewhat limited due to its brittleness.
Now, an alternative bio-based
used inverse glassy structures to develop
noniridescent colors in the full visible range.
The air cavities have short optical lengths,
yielding weak cavity resonance out of the
visible range. Also, to provide easy material
processing and high mechanical stability
of the inverse glasses, the group employed
photocurable suspensions containing amorphous
arrays of concentrated colloids that
serve as templates to produce amorphous
arrays of air cavities in a polymerized matrix.
To prepare the suspensions, the group
dispersed silica particles in the photocurable
resin, which forms thin solvation layers on the
surface. For a certain range of concentrations,
the silica particles form a non-closelypacked
amorphous array. The colloidal array
can be rapidly captured by photopolymerizing
the medium, which is then removed
by selective etching, thus yielding inverse
glassy structures.
The inverse glasses exhibit noniridescent
structural colors under diffuse light. The colors
can be tuned in full visible range by adjusting
particle diameter.
High-performance composite based on biomass
The material has an impact resistance value
composite material has been developed that
overcomes this limitation. Developed by the industry-university
consortium of Hitachi Zosen
Corp. (HITZ; Osaka City, www.hitachizosen.
co.jp and Osaka University, under the New Energy
and Industrial Technology Development
Organization (NEDO; Kawasaki City, all Japan;
www.nedo.go.jp), the composite is made by
dynamically cross-linking and combining PLA
with 10-30 wt.% of trans-polyisoprene, which
is derived from the non-edible biomass of Eucommia,
a tree native to China whose bark is
used for medicines.
ast April, a demonstration plant
started up for the production of hydrogen
from aluminum-based composite
waste. The startup marks
the culmination of a project, supported by
NEDO, in which Alhytec Inc. (Takaoa City,
Japan; www.alhytec.co.jp) developed the
process to separate the aluminum from
waste composite materials and generate H2
to be used for fuel-cell power generation at
Asahi Printing Co.'s Toyama Plant. The demonstration
plant has a production capacity of
approximately 16-25 times greater than commercially
available PLA. The elongation, one
of the tensile properties, has also been drastically
improved by a factor of approximately
9-30 times. It is expected that this biomassderived
composite material will be used as
resins for 3-D printing, which has a growing
global market for use in automobile interiors
and components that normally are made in
molding processes. Other potential applications
include bio-based sporting goods, office
equipment and medical devices.
The partners are investing several million
dollars in a 10-ton/yr mass-production line to
manufacture the composite, and expect to
begin shipping products later this summer.
Making H2 from aluminum composite waste
2 kg/h, and the company plans to enhance
the H2 generation to up to 5 kg/h.
The system is composed of three steps,
a pulper-type separator, using a high-speed
rotator wing for separating plastics and aluminum;
a pyrolysis furnace for decomposing
the plastics and removing the aluminum;
and the H2 generator, in which the H2
is produced by the reaction of Al in an alkaline
solution. The technology is expected to
find applications at printing, packaging and
metals factories.
n
ChemiCal engineering www.Chemengonline.Com July 2016
large quantities of unwanted
products, making
it unfavorable as a way to
utilize natural gas for making
chemicals. Now, researchers
at ETH Zurich
(Switzerland; www.ethz.
ch) have discovered a vanadium
phosphate catalyst
with a high selectivity,
which makes it possible
to brominate methane in a
single step at atmospheric
pressure and temperatures
below 500°C. The discovery
could enable the use of
CH3Br as an alternative to
synthesis gas (syngas) as
the building block for making
fuels or complex chemicals,
such as polymers or
pharmaceuticals.
Currently, methane is industrially
converted into
higher-grade chemicals by
steam reforming, which requires
high pressures (up to
30 bars) and temperatures
(up to 1,000°C).
The new catalyst - described
in a recent issue of
Nature Chemistry - is said
to be exceptionally stable,
and resistant to corrosive
halogen environments.
a bioaCtive FilM
Polyether ether ketone
(PEEK) has mechanical
properties similar to bone,
making it attractive for use
in spinal implants. However,
PEEK doesn't bond well
with bone. Now, researchers
have developed a technique
for coating polymer
implants with a bioactive
film that significantly increases
bonding between
the implant and surrounding
bone in an animal model.
The advance could significantly
improve the success
rate of such implants, which
are often used in spinal surgeries.
The work was done
by researchers at North
Carolina State University
(Raleigh; www.ncsu.edu),
the University of Cambridge
(U.K.; www.cam.ac.uk) and
the University of Texas at
San Antonio (www.utsa.
edu), and is described in
a recent issue of Materials
Science and Engineering.
13
http://www.ethz http://kaist.ac.kr http://www.hitachizosen http://www.co.jp http://www.nedo.go.jp http://www.ncsu.edu http://www.cam.ac.uk http://www.alhytec.co.jp http://www.utsa http://www.Chemengonline.Com
Chemical Engineering July 2016

Table of Contents for the Digital Edition of Chemical Engineering July 2016
