-
Q: Why do water and oil not mix? Ialways thought it was because
oil was less
dense than water, but my teacher said that
water molecules would rather stick to other
water molecules, and oil molecules would
rather stick to other oil molecules, and that's
why they don't mix. He says like dissolves
like. Which one of us is right?
A: A lot of people learn that oil floats onwater because it is
less dense, and they inter-pret this to mean that oil and water do
not mixbecause oil is less dense. Its low density iswhat makes the
oil end up on top of the wateras they separate, but it's not what
prevents thetwo liquids from mixing in the first place. For abetter
explanation, I have to side with yourteacher on this one: The
inability of water andoil to mix (also known as immiscibility) is
adirect result of intermolecular preferences,but it turns out that
what your teacher is say-ing has a common misconception in it as
well.
Before we get to that misconception,though, lets talk polar. Not
quite as in northpole but as in diametric, or in plain
English,opposite ends. Molecules are held together bycovalent bonds
consisting of pairs of sharedelectrons. If one of the atoms in the
bond pullsthe electrons more strongly, that tends toattract the
electrons toward its end of the mol-ecule. This gives that
electron-rich end a par-tially negative charge (-) and the
otherendthe atom end where the electrons havemade themselves
scarcea partially positivecharge (+). These attractions are known
asdipole-dipole attractions. Particularly strongdipole-dipole
forces are present among mole-cules where hydrogen is bound to an
atomwith a very strong pull on the shared electrons(namely,
nitrogen, oxygen, and fluorine), andgo by the name hydrogen bonds.
Water is anexample of a molecule that forms hydrogenbonds. This is
significant because it makeswater molecules very sticky to one
anotherwith the (-) end of one molecule attracted tothe (+) end of
a neighboring molecule.
But what about the oil? The bonds withinan oil molecule consist
of pairs of electronsthat are shared pretty equally between the
par-ticipating atoms. The result? Because there areno (-) and (+)
ends, these bonds are nonpo-
lar and the moleculeoverall is considered tobe nonpolar as
well.There is, however, ran-dom movement of theelectrons within
thesemolecules, and this canlead to temporary lop-sidedness in
theircharge distribution andproduce momentary +and - portions of
themolecule. These, inturn, can lead to very weak attractive
forcesknown as induced dipole-induced dipole, orLondon forces.
Because hydrogen bonding inwater contributes a substantial amount
ofcohesive energy, over and above the Londonforces present, water
is a liquid, whereas othermolecules of similar size but lacking
waterspolarity, such as methane, ethane, fluorine, orcarbon
dioxide, are gases at room temperature.
And now for the misconception: yourteacher's explanation makes
it sound asthough the immiscibility of oil and water is oneof
mutual agreement and that there is noattraction existing between a
water moleculeand an oil molecule. Some teachers go as faras to say
that oil and water molecules repelone another. In fact, the term
often applied tononpolar substances such as oil is hydropho-bic,
which means water fearing. The truth isthat an oil molecule is very
attracted to a watermoleculeeven more than it is to another
oilmolecule. Because the water molecule has afixed polarity (a
permanent dipole), it is muchmore capable of inducing a temporary
dipolein a nearby oil molecule than is another nonpo-lar oil
molecule. The (+) end of the water mol-ecule attracts the electrons
in the oil molecule
2 ChemMatters, APRIL 2006
Production TeamTerri Taylor, EditorCornithia Harris, Art
DirectorLeona Kanaskie, Copy EditorMichael Tinnesand, Contributing
Editor
Administrative TeamTerri Taylor, Administrative EditorSandra
Barlow, Senior Program AssociatePeter Isikoff, Administrative
Associate
Technical ReviewSeth Brown, University of Notre DameDavid Voss,
Medina High School, NY
Teachers GuideWilliam Bleam, EditorDonald McKinney, EditorSusan
Cooper, Content Reading ConsultantDavid Olney, Puzzle
Contributor
Division of EducationMary Kirchhoff, Acting DirectorMichael
Tinnesand, Associate Director for AcademicPrograms
Policy BoardDoris Kimbrough, Chair, University of
ColoradoDenverRon Perkins, Educational Innovations, Inc., Norwalk,
CTBarbara Sitzman, Tarzana, CA Claudia Vanderborght, Swanton,
VTSusan Gleason, Middletown, DE
Frank Purcell, Classroom Reviewer
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Printed in the USA
COVER PHOTOGRAPHY BY MIKE CIESIELSKI
By Bob Becker
Question From the Classroom
http://chemistry.org/education/chemmatters.html
MIK
E CI
ESIE
LSKI
-
up close to it and this creates a (-) end rightthere next to the
water's (+) end. Likewise,the (-) end of the water molecule repels
theelectrons in the oil molecule to the far side,and this creates a
(+) end right there next tothe waters (-) end. These are known
asdipole-induced dipole attractions, and they aresignificantly
stronger than the induced-dipole-induced dipole attractions acting
between twoneighboring oil molecules.
What this means is, if you were an oilmolecule, you would much
rather surroundyourself with water molecules than with othersof
your own kind. If that's the case, why thendo oil and water not
mix? If it were up to theoil, they would. But it turns out that the
dipole-dipole attractions described above are somuch stronger than
dipole-induced dipole, thatit is really is the water molecules that
are call-ing the shots. Water molecules are far tooattracted to
their own kind to ever allow any oilmolecules to come in-between.
In short, watermolecules are very cliquish. They will allowother
polar molecules such as ethanol orammonia to enter their exclusive
company, buta nonpolar molecule: no way! The only mole-cules that
would associate with nonpolar mol-ecules would be other nonpolar
molecules.
So even though its true: oil and waterdont mix, it is hardly by
mutual agreement. Areally impressive illustration of this
discrep-ancy occurs when a drop of water is placedon a nonpolar
surface such as wax paper.The drop of water beads up into a
sphere-barely touching the wax paper. One canalmost visualize the
water molecules all gath-ering together in their exclusive club,
notwanting to associate with those lowly waxmolecules at all! But
when the tables areturned, and a drop of nonpolar liquid isplaced
on a polar surface, such as occurswhen a drop of motor oil falls
onto a wetpavement, a very different outcome isobserved. Rather
than beading up into a tinysphere, the oil drop spreads out into an
infini-tesimally thin layerthis is what causes thecool concentric
rainbow patterns. In thisarrangement, each oil molecule is in
mini-mum contact with other oil molecules, forwhich the attractions
are so weak, and inmaximum contact with the much more attrac-tive
water molecules.
In this way, like does dissolve like: Polarsubstances dissolve
other polar substances,and nonpolar dissolve nonpolar, but for
polarsubstances, it's a matter of preference and fornonpolar ones,
it's more a matter of settlingfor what you can get!
Vol. 24, No. 2 APRIL 2006
ChemMatters, APRIL 2006 3
Question From the Classroom 2Why do water and oil not mix?
ChemSumerThe Dog Ate My Homework and Other Gut-Wrenching Tales
4
Midge, a fun-loving dalmation has a taste for paper.When she
eats $180 in cash and checks, can it berecovered?
Sneeze and Wheeze 7Learning how allergic reactions occur is
often the key to living with and controlling the misery they
create.
Bling Zinger ... The Lead Content of Jewelry 11Could your
jewelry make you sick? For one small child,the answer was yes.
GreenChemBiomimicryWhere Chemistry Lessons
Come Naturally 15From spiders to beetles to mussels, some
chemiststurn to nature for inspiration.
Nanomotors 18Some synthetic and others natural, these tiny
motors aresimilar to the motors in your favorite household
appliances.
Chem.matters.links 20
CMTEACHERS! FIND YOUR COMPLETE
TEACHERS GUIDE FOR THIS ISSUE
ATwww.chemistry.org/education/chemmatters.html.
PHOTODISC
PHOTODISC
on theweb
on theweb
on theweb
on theweb
-
4 ChemMatters, APRIL 2006
http://chemistry.org/education/chemmatters.html
The crimeRecently, Midges owners Kit and Steven
were serving as hosts for a favorite singer/songwriter, an old
acquaintance who was intown for a local concert. Things went
welluntil the door to the guest bedroom was leftajar. Under normal
circumstances the opendoor would not have been a problem, but
forlovable Midge, it was a doorway to opportu-nity. There, on the
bedside table was $180 incash and a check. So tempting! Not to
men-tion delicious!
When the break-in was finally discov-ered, all that was left was
a few shreds of thecheck. No sign of the $180 cash. Thus, thewait
began. For Kit and Steven, walking thedog took on an entirely new
sense of pur-
pose. Picking up after Midge required anadditional close
inspection to see if any of thebills made it through her digestive
systemintact. The project gave money laundering awhole new meaning.
Gross? Definitely. Butluckily, there was some good chemistryworking
in favor of retrieving the cash.
The chemistry ofdigestion
At the most fundamental level, the bio-logical processes of
digestion and metabo-lism are all about the breaking and making
ofchemical bonds.
Basically, digestion consists of breakingfood down into
molecules small enough todiffuse through the thin walls of blood
ves-
Youd love Midge.
Shes your ordinary,
fun-loving dalmatian
with a great
personality and one
bad habit. She loves
the taste of money,
paper money!
By Michael Tinnesand
The Dog Ate MyHomeworkand Other Gut-Wrenching Tales
The digestive system of a dog.
-
ChemMatters, APRIL 2006 5
sels. After transport through the body, theycross over into
tissues where they areabsorbed and used by living cells.
Food is primarily composed of large bio-molecules such as
proteins, fats, and carbohy-drates. The breaking down of food is
thebreaking of chemical bonds that hold the mole-cules of the food
together. After the moleculesof food are broken down into small
enoughpieces for cells to absorb them, they are eitherconsumed
completely for fuel or reassembledinto new polymers and other
molecules,according to the bodys own blueprint.
The process of breaking bonds in foodincludes a number of key
steps. Except foranimals like pythons who swallow their foodwhole,
the process of digestion usuallybegins with a physical phase.
Chewing breaksthe food into smaller pieces, thereby expos-ing more
surface area, which accelerates theprocess of digestion.
Next, most animals have some sort ofspecialized sac or pouch,
such as a stomach,where serious digestion gets under way. Inhumans,
a strong acid secreted by the stom-ach helps break down tough
connective tis-sues and activates a set of biological
catalystscalled enzymes. Like all catalysts, enzymesgreatly
accelerate the rate of chemical reac-tions without being used up in
the process. Asingle enzyme molecule can catalyze a reac-tion
thousands of times. But that is not to saythat an enzyme is able to
catalyze thousandsof different reactions. In fact, most
enzymescatalyze single specific reactions.
This is easier to understand once youunderstand how enzymes
work. In what isoften called the lock and key model,enzymes
participate in chemical reactionsbased on the shape and structure
of thereactants. An enzyme can join reactants(often called
substrates) together by offeringadjacent surface features where the
reac-tants can fit. In this case, the enzyme makesit much easier
for bonds to form in a reac-tion that is already energetically
favorable.
Enzymes lower the activation energy, theenergy required to start
the reaction, bysecuring the reactants in a geometricallyfavorable
position. Held this way, the mole-cules react with little initial
energyless than if they had to rely on random collisionsto bring
them together. Once bonded, they are released, and the enzyme is
free to actagain.
Enzymes can also work to break bonds.In this case a single
molecule fits with theenzyme in such a way that one particularbond
is stressed. This stress lowers theenergy requirement for breaking
the bond.
Because the interactions between theenzyme and the substrate
molecules aretotally dependent on shapes, each reactionrequires its
own enzyme. Virtually all of the
chemical reactions that occur in living cellsrely on one or more
enzymes to allow themto occur at a useful rate. Just like each
lockrequires a key with just the right shape, eachchemical reaction
requires an enzyme withthe right shape.
And all of this explains why Kit andSteven were optimistic about
seeing their$180 again, even after it had been subject toMidges
digestive process and the accompa-nying onslaught of enzymes.
enzyme-substratecomplex
substrate enzyme
Activ
e si
te
breakdownof substrate
enzymeready torepeat action
Chem
ical
pot
entia
l ene
rgy
Activated reactants(uncatalyzed)
Reactants
Activated reactants(catalyzed)
Products
Time
The only difference between starch top and cellulose bottom is
the way the ring-shaped glucosemolecules are connected
(blue-colored bonds).
The red line in this graph shows the loweractivation energy in a
catalyzed reaction.
ACS
STAF
F
The lock and key model of enzyme action.
-
http://chemistry.org/education/chemmatters.html6 ChemMatters,
APRIL 2006
Cellulosedefyingdigestion
The enzymes found in humans and otheranimals allow them to
digest and metabolizemany, but not all, biomolecules. Cellulose
isone example of a molecule that defies diges-tion in many animals.
This is an interestingexception because cellulose, a
structuralmaterial found in plant cell walls, is made upof the same
glucose subunits as digestiblestarch. Glucose is a simple sugar
that pro-vides fuel for most organisms. But the slightdifference in
the way the glucose moleculesare hooked together in starch,
compared withhow they are hooked together in cellulosemakes a big
difference in their digestibility.Humans and many other higher
animals havethe enzyme required to break the bonds instarch,
releasing glucose. But because theshape of the linkage is different
in cellulose,the same enzyme will not work. Infact, where cellulose
is concerned,humans do not have an enzyme thatwill work. Neither do
dogs. Whichbrings us back to Midge.
Paper money is made of cellu-lose in the form of very
high-qualitycotton and linen fibers. This cellulosenot only resists
the chemicalprocesses that are a part of diges-tion, but also
withstands themechanical breakdownchewingand shreddingthat is part
of thedigestive process.
As it turns out, most humanseat a fair amount of cellulose in
theform of fruits and vegetables. Although wecannot digest it, the
cellulose serves asroughage or fiber that gives food bulk andkeeps
it moving through the digestive sys-tem. In the end, all of the
undigested materialends up being eliminated as feces.
The end ...And so it was that Kit and Steven, with
patience and endurance, were at last able torecover their $180.
Midge, like the goose thatlaid the golden egg, eventually passed
all ofthe well-chewed bills in her feces.
Maybe you are wondering how animalssuch as cattle, sheep, deer,
and goats thriveon a diet of grass or other cellulose-rich food.Can
they digest cellulose when humans can-not? The answer is no. None
of these animalshave the enzymes required to digest cellu-
lose. Instead they rely on colonies of microor-ganisms living in
their digestive systems.These simple microorganisms have the
cor-rect enzymes to digest the cellulose and toreassemble the
products into starches andproteins. From these products, grazing
ani-mals acquire their nutrients. The special rela-tionship between
these animals and theirresident microbes is called
symbiosistwoorganisms living with each other to the bene-fit of
both.
As for Midge, it was a happy ending forall concerned. Withthe
cash recovered,Midge eventuallygot out of thedoghouse, andthe
songwriterwas even inspired towrite a new song tocommemorate
theentire affair.
So what are thechancesin theextremely rare casethat a dog really
DID eat your homeworkthat it might show up again undigested on
thefront lawn? Not good. The chemicalprocesses that break down
cellulose in thepaper-making industry leaves a weaker formof
cellulose in the productso weak thatthere is little likelihood of
it making its waythrough a dogs digestive system.
Better idea? Save to disk! Avoid mag-nets. But that's another
story Photomicrograph of cellulose fibers shows their linear
nature.
The paper currency is clearly intact after passing through the
dogs digestive system.
Michael Tinnesand is the Associate Director ofAcademic Programs
at ACS. His most recent article,Whats So Equal about Equilibrium,
appeared inthe September 2005 issue of ChemMatters.
Glucose is fuel for most organisms and the buildingblock for
both starch and cellulose. Humans (anddogs) can break down starch
into glucose but notcellulose.
PHOT
O DI
SC
-
Look around and youll see many little chemical factoriesin
nature that are nonpolluting and environmentallyfriendly. Inside a
leaf or a bug, there lies some sophisti-cated chemistry, often
turning out incredible materials
that are the envy of todays chemists and engineers.In fact, you
might say that todays industrial chemists
are developing a green thumb. Green chemistry is thedesign of
chemical products and processes that reduce oreliminate the use and
production of hazardous substances.Green chemists look for new ways
to do chemistry that isbenign by design, thus preventing pollution
before it starts.
Why are chemists turning to nature for ideas? Thinkabout it.
Nature uses renewable sunlight for energy andrecycled starting
materials to make a lot of things. Organ-isms synthesize medicines,
plastics, and all kinds of otheruseful materials without releasing
toxic chemicals into theenvironment or using large amounts of heat
or pressure.Natures chemistry embodies many of the principles
ofgreen chemistry, using processes that have met the testsof
time.
Scientists call the study of these natural chemicalprocesses
biomimicry, a term that means imitating life andinvolves applying
nature's lessons to new human inven-tions. Janine Benyus, the
author of Biomimicry: InnovationInspired by Nature, calls it the
conscious emulation of lifesgenius. But that's not to say that
every process in nature isnonpolluting. For example, it is well
known that animalsrelease carbon dioxide and methane, greenhouse
gases,into the environment.
Although biomimicry is getting increased attentiontoday, several
famous inventions of the past were inspired
by nature. Take the telephone, for instance. Alexander Gra-ham
Bell studied the human tongue and eardrum to helphim design the
first telephone. The Wright Brotherswatched birds gliding in the
wind for shaping airplane wingsbefore taking the first flight. And
nearly everyone is familiarwith synthetic Velcro, which was
inspired by the way thetiny hooks on seed pod burrs attach to the
loops of threadin cloth.
Whether forms, processes, or systems, biologyincludes a wealth
of ideas for chemists and engineers.When scientists apply the
methods and systems practicedin nature to cutting-edge research
challenges, creative andamazing scientific breakthroughs often
occur.
Spiders spin webs strongerthan steel
Dragline silk from a golden orb weaver spider is fivetimes
stronger than steel (when compared gram for gram),
ChemMatters, APRIL 2006 15
GreenChem
How do they do that? How do spiders spin a web that's
strongerthan steel? How do bombardierbeetles launch chemical bombs
attheir enemies without hurtingthemselves? How do tiny musselsstick
to rocks in the pounding surf?How do green plants generate asteady
supply of safe and renewable energy?
By Kathryn E. Parent and Jennifer L. Young
BIOMIMICRYWhere ChemistryLessons ComeNaturally
PHOT
ODIS
C
-
16 ChemMatters, APRIL 2006
http://chemistry.org/education/chemmatters.html
and can absorb five times the impact force ofKevlarthe synthetic
fiber of bullet-proofvestswithout breaking. Whats more, it
canstretch 40% longer than its original length.For the spider, the
durability and strength ofsilk means food. And for humans, it
couldmean an amazingly useful fiber that can bemade from safer and
less hazardous chem-istry. Science writer Steve Miller describes
theproperties of good web fiber in a February2001 ChemMatters
article: It must be strongenough to bear the weight of a
bungee-jump-ing spider, flexible enough to withstand theimpact of a
flying insect, and stable enough tolast for days. And it cannot
require moreraw material than the spider can replenishfrom ordinary
food resources. Even the U.S.military has taken notice. The U.S.
Army hasinterest in a manufactured version of draglinesilk for
applications such as catching fighterjets as they land on aircraft
carriers.
How does a spider make such an incredi-ble fiber that humans
have not yet fully repro-duced? Scientists are still studying
thechemical composition of the spiders silk. Sci-entists know that
spider silk is a protein andhave identified the amino acids that
are itsbuilding blocks. Glycine and alanine are themost abundant
amino acids in the silk (seeFigure 1). The three-dimensional
structure ofthe fiber, which gives it the strength and
flexi-bility, results from how the amino acid build-ing blocks
interact with each other. As a resultof the diversity of amino acid
interactions,some parts of the silk fiber are highly oriented,like
uncooked spaghetti, and other parts arevery nonoriented like cooked
spaghetti.
To make the silk fiber, the spider synthe-sizes liquid protein
by putting together theamino acid molecules and squeezes the
pro-tein through a spinneret (i.e., to spin thefiber). When it
exits the spider, the soluble liq-uid protein becomes an insoluble,
highlyordered, and extremely strong fiber. With thisknowledge,
scientists are trying to make afiber that is similar to spider
silk. This much iscertain: spiders dont use the high pressures,high
temperatures, or corrosive acids oftenused in chemical syntheses.
In manufacturingKevlar, for example, industrial chemists relyon hot
concentrated sulfuric acid. Nylon fiber,used in ropes and cords for
rock climbing andparachuting, is manufactured under condi-tions of
high pressure and temperature. Thegolden orb weaver spider manages
to producea high-performance fiber using chemistry mildenough to
occur inside their bodies.
The bombardier beetle bomb
Bombardier beetles can fire, literally, amixture of chemicals at
predators. To preparefor attack, the beetles produce and store
twochemicals, hydroquinone (C6H6O2) and hydro-gen peroxide
(H2O2).
When the mixture of chemicals is pushedfrom the storage
reservior into the firingchamber, enzymes in the chamber wall
reactto release free oxygen (O2) and steam (H2O).They also oxidize
the hydroquinone to benzo-quinone, which is an irritant (see Figure
2).The resulting reaction is extremely exother-mic. Heat and
pressure force the chemicalspray out an opening in the beetles
abdomenwith a loud bang. The chemistry is simple,but the biology is
beautiful said Jerrold Mein-wald, a researcher at Cornell
University.Despite the heat, pressure, and irritatingchemicals
emanating from its body, the beetleremains largely unaffected.
Unfortunately, thenews isn't as good for its enemies.
The March-April 2004 issue of AmericanScientist features the
research of Andy McIn-tosh, a professor of thermodynamics
andcombustion theory at the University of Leedsin England. He is
working to apply the bom-bardier beetles methods to find a better
wayto reignite aircraft gas turbine engines.Beyond engine
reigniters, McIntosh envisionsfuture applications of the bombardier
beetlesdesign, including rocket technology, automo-
bile airbags, and unmanned aerial vehicles,though all of these
are beyond the scope ofhis current study. "I think the natural
world isfull of excellent designs that we can learnfrom," McIntosh
says.
Blue mussels make glue
Visit the seashore and you'll find mus-sels clinging steadfastly
to rocks, despite thecrashing surf. How do they do it? Professor
J.Herbert Waite from the University of Delewarehas been researching
this question for morethan 30 years. The mussels are able to
applytheir protein-based glue underwater, where itcures and sticks
to nearly anything amidst theharsh ocean. They do it with
chemistryWaite realizes. But so far, no chemist has suc-cessfully
synthesized this incredible marinesuperglue. Clearly, the product
would be aboon to boaters of all descriptions. With aglue like
that, they would no longer have todry-dock boats for repairs.
Professor Kaichang Li, a wood chemistryexpert at Oregon State
University, used mus-sels as his model for developing a new
soy-based wood adhesive. He explains, Inspiredby the strong and
water-resistant binding ofmarine organisms such as mussels to
rocksand other substances, we are investigatingconversion of
renewable natural resourcessuch as soy protein, carbohydrates, and
ligninto strong and water-resistant wood adhe-
OH
OH
H2O2
O
O
H2O O2
Hydroquinone Benzoquinone
+ +
Hydrogen peroxide
Catalyst+ + Energy
Water(steam)
Oxygen(gas)
Heat
H
C COOHH2N
H
CH3
C COOHH 2N
H
glycine alanine
Figure 2. Oxidation of hydroquinone.
Figure 1. Chemical structures of glycine and alanine.
-
sives. He noticedthat the chemicalstructure of the pro-teins in
the musselsglue included a lot ofringed hydroxylchemical
structures.By modifying soyprotein (e.g., tofu) toincorporate more
ofthese types of struc-tures, Li has devel-oped a new glue thatis
stronger and more
water-resistant than the traditional formaldehyde-based
adhesives usedto make plywood. Even better, the glue doesnt release
hazardous airemissions during manufacturing processes or from the
finished ply-wood boards. Thats good news for the environment, for
plywood man-ufacturers, and for consumers of plywood.
New directions in biomimicryresearch
Writer Alexandra Goho, in a Science News Online February
12,2005, article, highlighted several chemists who are using nature
forinspiration in their laboratories. For example, Dr.David Liu at
HarvardUniversity has found ways to use one of natures premier
templates,DNA, like a molecular laboratory for synthesizing
chemicals in minisculebatches. DNA controls the order and amount of
chemicals that reactduring a given process, limiting the number of
undesired by-products.
At Cornell University, Dr. Tyler McQuade looks to cell biology
forinspiration to develop an assembly-line system to make drugs
likeProzac. His microcapsule enzyme-mimic approach, controls the
order inwhich reactions take place, minimizing separation and
purification stepsthat typically generate large amounts of
waste.
Dr. John Warner at the University of Massachusetts-Lowell
recog-nizes seashells as models for lowering the energy required to
producesolar cells. To make their shells, mollusks rely on small
organic mole-cules to choreograph the assembly of calcium carbonate
(CaCO3) intoelaborate mineral structures. When Warner looked at
films of titaniumdioxide (TiO2), used as an alternative to silicon
(Si) metal for solar mate-rial, he saw a resemblance to the
structure of seashells. So, Warner
tried using small organic molecules with multiple carboxylic
acids(RCOOH) to assemble titanium dioxide particles into films of
solar mate-rial. He was able to accomplish it at room temperature,
a tremendousenergy savings over traditional manufacturing methods
that requireheating titanium dioxide (TiO2) films at 500 C.
The examples above show the incredible variety in the
researchchemists and engineers approach using biomimicry. Imagine
what wecan create, using examples in nature to find new and better
ways todesign materials, processes, and systems.
ChemMatters, APRIL 2006 17
ReferencesBellis, M. Famous InventionsA History of
Inventions
Available at http://inventors.about.com/library/bl/bl12.htm
(accessed Jan. 20, 2006).
Benyus, J.M. Biomimicry: Innovation Inspired by Nature. New
York:Morrow, 1998.
Biomimicry Guild. Available at http://www.biomimicry.net/
(accessedJan. 20, 2006).
Goho, A. Chemistry au Naturel Science News Online. 167,
2005.Available at
http://www.sciencenews.org/articles/20050212/bob8ref.asp or
http://www.phschool.com/science/science_news/articles/chem_au_naturel.html
(accessed Jan. 2006).
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http://woodscience.oregonstate.edu/faculty/li/ (accessed Jan. 20,
2006).
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(accessed Jan. 20, 2006).
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2000.Available at
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athttp://en.wikipedia.org/wiki/Biomimicry (accessed Jan. 20,
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Kathryn E. Parent and Jennifer L. Young are staff of the
American ChemicalSocietys Green Chemistry Institute
(www.greenchemistryinstitute.org).
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Not even asthma canstop Olympians fromgoing for gold!
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More on nanomotorsSynthetic nanomotors are an
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stu-dents is described as a gold rotorattached to a carbon
nanotubeshaft. To view pictures and videoof this 500-nm motor in
action,visit
http://www.berkeley.edu/news/media/releases/2003/07/23_motors.html.
Chemists celebrateEarth Day
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