The Mole
… FOR ANYONE INSPIRED TO DIG DEEPER INTO CHEMISTRY
Stamping down on
soggy shoes
The British nano-coating company P2i is putting an end to wet feet.
Josh Howgego and Nina Notman find out how to stay dry.
ISSUE 04 | JULY 2012
In this issue
Chlorophyll
Food from sunshine
Avogadro’s lab
Find out how to
whip up an
emulsion
UCAS personal
statements
It’s not hard to see why a British company should be
leading the way with new waterproofing technology:
we are, of course, world-renowned for our wet
weather! The technology sold by Oxfordshire-based
P2i was originally designed to improve the chemical
protection of soldiers’ clothes, but since then this
innovative chemical coating has been developed for
use in more familiar locations.
Expert advice to help you
make yours stand out from
the crowd
How it works
Cutting-edge chemistry
The degree to which water is attracted to or
repelled from a surface is determined, at the most
fundamental level, by the intermolecular forces
between the two phases. There is a general rule in
chemistry that ‘like interacts with like’. Since water
is highly polar it ‘likes’ to dissolve charged ions
such as Na+ and Cl-. It doesn’t like to interact with
non-polar things, which is why oil spills float on the
ocean, rather than mixing into it.
The same principles are used by coatings chemists.
When they find a material that water doesn’t like
to interact with, there’s a good chance it’ll make a
decent repellent. Of course, whether one material
interacts with another is not really about whether
they ‘like’ each other. It’s more accurate to think
about how the overall energy of the system changes
when contact happens. To make an interaction more
favourable, the energy of the system must decrease
overall (∆G < 0) when the two materials come into
contact with each other. If the energy increases
overall (∆G > 0), they will be mutually repelled.
University teaching
Prepare for the classroom
to lecture transition
How plants mop up
oil spills
Editor
Karen J Ogilvie
Assistant editor
David Sait
ChemNet content
Rio Hutchings
Production
Scott Ollington and Emma Shiells
Publisher
Bibiana Campos-Seijo
The Mole is published six times
a year by the Royal Society of
Chemistry, Thomas Graham
House, Cambridge,
CB4 0WF.
01223 420066
email: [email protected]
www.rsc.org/TheMole
© The Royal Society of Chemistry,
2012. ISSN: 2049-2634
www.rsc.org/TheMole
Registered Charity Number 207890
0412MOLE - FEATURE.indd 1
6/11/2012 1:24:58 PM
Fig 1: For a standard PTFE
coating (top) incoming water
droplets ‘see’ CF2 units,
whereas with P2i’s coating
(bottom) the molecules ‘see’
a terminal CF3 group
PTFE is a common material which has
well known applications as a water
repellent coating. As well as a saucepan
coating (Du Pont’s Teflon®), it is used as a waterproof
membrane barrier in shoes and outdoor clothing.
Looking at the chemical differences between normal
PTFE and P2i’s chemicals, it may come as no surprise
that the latter is more effective. ‘The change going from
CF2 to CF3 groups is sufficient to reduce the surface
energy [of P2i’s coatings] to about a third of that of
regular PTFE’ says Evans. ‘Because you have reduced the
surface energy that much, the water will tend to bead up
and just roll off it. Basically, the water interacts much less
with the surface, so it interacts with itself more.’
Soggy shoes: a thing of the past
Did you
know?
The P2i coating started
out as a project for the
Ministry of Defence to
develop coatings that
would repel poison gases
like VX gas (O-ethyl S-[2(diisopropylamino)ethyl]
methylphosphonothioate)
and mustard gas (bis(2chloroethyl) sulfide).
2 | The
2 | The
MoleMole
| March
| July2012
2012
0412MOLE - FEATURE.indd 2
One of the most obvious applications for the new
technology is outdoor footwear, and sure enough, P2i
have quickly stormed into the market. The launch of
the technology was with trainer brand Hi-Tec at first,
explains Evans, but since then other household names
like Teva, K-Swiss and Timberland have started using
the coating on their shoes too.
Unlike traditional water repellent coatings, P2i’s
technology (which, when applied to shoes, is branded
ion-maskTM) actually forms a covalent bond between
the coating and the shoe substrate. Most coatings
are held to their substrate simply by weak
intermolecular forces, and so are
inherently weaker and less
durable than ion-maskTM.
‘Most other water
resistant coatings are just physically
dried on,’ says Evans.
Water beads roll off shoes coated with ion-mask™
© P2I 2012
P2i understand this chemistry pretty
well. Delwyn Evans, a senior principal
chemist at P2i, explains their coating is
a lot like polytetrafluoroethylene (PTFE)
– the non-stick material which coats
saucepans in kitchens up and down
the country – but with an important
difference. ‘PTFE is the benchmark
material for having a low surface
energy’ says Evans. ‘All PTFE consists
of is polymeric chains of CF2 groups.
(fig 1) What we have with the polymer
that we grow, is that on the upper
surface of the coating are CF3 groups.
The chains are orientated so they are
perpendicular to the surface, rather
than aligned flat with the surface, as
with other coatings.’
creating radicals; that is, unpaired electrons. ‘Once
you’ve got the free radicals [on the surface], we turn
the power off and introduce the fluorocarbon-based
monomer,’ says Evans. ‘This starts attaching to all the
free radical sites that were generated in the first stage.’
Now there is a nanoscale film of polymer on the shoe
surface. To propagate the reaction, and begin to build
up the comb-like strands of polymer perpendicular
to the shoe surface, more short bursts of plasma are
used to create further radicals in the film and keep the
polymerisation process going (fig 2). The process is
quick – it takes between 10 and 30 minutes to finish.
Treated shoes are good news for long distance runners
as their shoes will not absorb water and gain any
weight in wet weather.
Evans says one of the biggest challenges for P2i has
been taking this laboratory process and working out
how it can be applied during a shoe manufacturer’s
production line. It has been the combination of science
with engineering that has given the step change that
allows its application to high throughput manufacturing.
‘There is a facility out in China where the shoes from
different brands can go, be processed and then come
back out,’ says Evans. ‘However, for other customers
we do try to fit it into their production line. That’s one
of the tricky bits for the business. It is relatively easy
to do on a university bench scale, but the trick has
been how you can deliver that
type of performance at the speed
that the customers
want it.’
‘The big technology
step we’ve been able
to do over the last
few years is in taking
the business from
the small
The P2i process
The process starts by putting the shoes into a
vacuum chamber and evacuating all the air. Radio
frequency plasma in the chamber is then used to knock
electrons out from the surface material of the shoe
www.rsc.org/TheMole
6/11/2012 1:25:29 PM
pulsed rf plasma
rf plasma
Surface activation
Surface attachment
Growth of coat
Finished coating
research level up to an industrialised process. We are
one of the few companies doing this who have been
able to industrialise on a really large scale.’
nanoscale [10-9 m] rather than on the micron [10-6 m]
scale,’ says Evans. That’s possible, of course, because the
coating is so much more effective than its competitors.
Fig 2: The P2i process
Water-resistant electronics
And in terms of the process, fewer chemicals are used.
The fluorocarbon-based monomer can be vaporised
directly due to the very high vacuum in the deposition
chamber. That means that unlike many of P2i’s
competitor coatings, which are applied by dipping the
shoe material into a coating solution, P2i’s process uses
no solvent at all. There is also no need to waste time
waiting for the shoe to dry off. Overall, P2i’s technology
is simple but highly effective. The sky seems to be the
limit for this technology; wherever water is an unwanted
and inconvenient companion, P2i can foresee a
potential market.
Find out more
It’s not just shoes and clothes that P2i can apply its
coating to. There are a host of consumer products that
would benefit from water repellency. One of the most
annoying things in modern life has to be dropping a
mobile phone or camera in a puddle, but with P2i, that
might be a forgotten frustration.
P2i are also active in the electronic devices market,
where they call their technology AridionTM. The main
challenge in working with different substrates (phone
casings, as opposed to shoe fabric) is working out how
to generate the radicals on the various surfaces.
site at:
Go to P2i’s web
to see videos
w w w.p2i.com
more
ts
lo
t
and find ou
t the
ou
ab
n
io
informat
ocesses.
pr
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lo
techno
Loading devices into the
vacuum chamber
‘Each product has its own particular challenge and
characteristics with activation and how they behave
in vacuum. So what you’ll get out of a leather shoe
– because leather retains a large amount of water –
would be different to what you’d get off a hard plastic.’
‘For each of the customers, we optimise the process for
individual products and then ideally provide them with
a machine. They just load it up, press the button and
that’s it; everything is automated.’
Despite these challenges, P2i has seen significant
success in recent years. ‘We were on over half the
world’s hearing aids that were manufactured last
year,’ says Evans. AridionTM works particularly well for
hearing aids – unlike solvent or water based coatings,
the AridionTM treatment is carried out on the fully
assembled device, giving a superior water-repellent
coating.
Environmental impact
www.rsc.org/TheMole
0412MOLE - FEATURE.indd 3
Dye sensitised solar cells
are easy and cheap to
manufacture
© P2I 2012
Another attractive feature of P2i’s technology is its low
environmental impact. ‘We use very small amounts
of chemicals, because the layer we grow is on the
July 2012 | The Mole | 3
6/11/2012 1:25:50 PM
Magnificent molecules
In this issue: chlorophyll
Did you
know?
Duncan McMillan appreciates the green glow
of nature and all that it provides
Absinthe was banned in
the European Union up
until 1988 over fears that it
caused hallucinations, fits
and delirium.
Ethylene glycol
(1,2-ethanediol)
causes electrons to be excited out of the chlorophyll
molecules and into a chain of reactions.
Chlorophyll B
Despite everything we know about
it, photosynthesis is a little magical. This
process turns photons into carbohydrates, ie
sunlight into food. This compound has effectively
built the largest, and longest-living, things from nothing
more than air, water, and light. The molecule that
makes it happen is chlorophyll.
Greens and yellows
Nature's little power-converter is a porphyrin ring
with a long side-chain. The porphyrin ring (shown
in green), the key constituent of the haem unit in
haemoglobin, contains a single magnesium ion.
Porphyrin's arrangement of alternating (conjugated)
single and double carbon-carbon bonds produces a
stable structure that absorbs visible light. When it is
combined with a metal ion it is often brightly coloured.
Find out more
ar tif icial
Shining light on
is
es
th
photosyn
)
ar tifphoto (pdf
http://bit.ly/TM
d β-carotene
Carotenoids an
0611 (pdf, p4)
http://bit.ly/IC
Chlorophyll's side chain 'tunes' the absorption
spectrum of the molecule. There are two main types
of chlorophyll (a and b). The composition of their
side-chains are different so can maximise a plant's
light-capturing potential – a is standard green and b is
a bit more yellow.
So, chlorophyll pigments give leaves a fresh green
and yellow tint. In autumn, deciduous plants stop
producing chlorophyll as they prepare to shed their
leaves. This reveals other pigments such as carotenoids
and xanthophylls, whose rich oranges and browns are
the colours of the season.
In this clever cycle, electrons pass through these
reactions and ultimately produce chemical energy
products which allow carbohydrates to be synthesised
from carbon dioxide and water (from the soil). The
chlorophyll is regenerated by electrons from the oxidised
water, so the leaves give oxygen gas as a by-product.
Artificial photosynthesis
Now scientists are working to hijack
photosynthesis for industry. The
sun dumps more solar energy onto the
earth than we might ever have use for; but even with
increasingly efficient solar cells the biggest problem to
overcome is storage. This is not a problem for plants
because they use the energy from the sun to build
complex carbohydrates such as sugars and starches to
store chemical energy, rather than electric potential.
Researchers are working on an artificial photosynthesis
that could improve on nature. By reducing the complex
process to simpler reactions, they hope to achieve a
higher energy conversion than in the humble green leaf.
On a more human note, chlorophyll is used in
food colouring. It is also present in the green spirit
absinthe, from the herbs it contains. Becoming so
fashionable at one point in France, particularly among
the artistic community, it is said to have inspired the
likes of Degas, Wilde, van Gogh, and Hemingway.
So chlorophyll is not only the source of life for virtually
every living thing, but was a source of inspiration in the
lives of some of our greatest artists.
Capturing photons
4 | The Mole | July 2012
0412MOLE - Pages 4-11.indd 4
SCIENCE PHOTO LIBRARY
In plants, chlorophylls are found in cell components
called chloroplasts. They capture the energy from
incoming photons. The chlorophylls are precisely
arranged within the cell proteins so that the energy can
be collected, channelled and focused. This eventually
www.rsc.org/TheMole
6/11/2012 3:18:24 PM
Avogadro’s Lab
In this issue: The chemistry of colloids
Paul Hogg whips up some edible colloids
What are colloids?
Milk, mayonnaise, paint, ointments, dust, blood, fog and
handcreams. We come across colloids every day, but what
are they? Basically, a colloid is made up of two or more
components that form a stable mixture – one component
acts as a continuous medium in which the other one is
dispersed. This mixture also has different properties from
its individual components.
An emulsion is a special type of colloid made up from
a mixture of two liquids which form a stable substance
that has different physical properties to the two
individual liquids.
Well known emulsions are milk and mayonnaise. Milk is a
mixture of water and milk fat and mayonnaise is a mixture
of oil and water, which is stabilised further by proteins in
the egg yolk. When separated, the two liquids are often
immiscible from one another.
A colloid is therefore a stable mixture that is made up from
two or more components. These components can be a
mixture of gas-liquid, liquid-liquid, solid-liquid or solid-gas.
The table shows a few examples of these combinations
Try this out
Let’s look at a gas-liquid colloid (foam) and a liquid-liquid
colloid (emulsion). Both of these colloids are found in our
everyday lives and will be very familiar to you.
 Using the whisk, mix the two components together.
Keep adding drops of olive oil until you get an
emulsion that looks similar to mayonnaise.
Changing appearances
In these two simple experiments, did you notice how
the physical properties and appearance of the mixtures
changed when the two components were mixed together?
A good way to scientifically measure the difference in
physical properties would be to take a ruler and incline it
at an angle of 45 degrees. Then take each of the individual
components and the colloids you have just made and
measure the time it takes for a drop of each liquid to travel
down the ruler by 10 cm. This will give you an indication of
the viscosity of the liquid.
You probably found that the individual components
were quite runny and slid down the ruler quickly, while
the colloids you made from them where quite thick and
stayed as blobs or slid down slowly – the colloids are more
viscous than their components.
Fascinating
Fact
The word colloid was
created by Thomas
Graham, who also gave us
Graham’s gas law
(http://bit.ly/GraLaw)
and who is also the person
who gives his name to the
Royal Society of Chemistry
offices in Cambridge, UK.
And finally…
In this experiment we have looked at some very common
colloids that can be found and made in our kitchens at
home. Colloids play a significant role in our lives but they
are often overlooked or taken for granted. See how many
more you can find; you will be surprised.
1. Gas-liquid colloid (a foam)
 You will need a whisk and some double cream.
 Take the whisk and whip the cream until it is very thick.
This is an example of a gas-liquid colloid, where gas is
trapped within a liquid to form a stable mixture.
2. Liquid-liquid colloid (an emulsion)
Did you
know?
 You will need two egg yolks (separated from the
white), a small amount of olive oil and a whisk.
Dispersive medium
Continuous
medium
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0412MOLE - Pages 4-11.indd 5
Gas
Liquid
Solid
Gas
None
Liquid aerosol eg fog
Solid aerosol eg smoke
Liquid
Foam
eg whipped cream
Emulsion
eg mayonnaise, milk
Sol
eg paint, blood
Solid
Solid foam
eg Styrofoam
Gel
eg jelly, cheese
Solid sol
eg pearl, ruby
The word colloid comes
from the greek ‘Kolla’,
meaning glue and ‘oid’,
meaning form. Together
they mean ‘glue-like’.
July 2012 | The Mole | 5
6/11/2012 3:20:01 PM
Preparing your UCAS
personal statement
Useful URLs
These handy websites will
help you to compose the
perfect personal
statement:
http://bit.ly/ucaspersta
http://bit.ly/studeps
http://bit.ly/cifeperst
Sue Thompson helps you get yourself noticed
A first draft
An excellent mind map to
help channel your
thoughts can be found at:
Now put this together but remember, you have limited
space – 47 lines or 4000 characters.
Use language which makes you sound enthusiastic
and interesting.
Be concise and be yourself – don’t use long words
you would not usually use.
Steer clear from trying to be funny – admissions tutors
may not share your sense of humour!
When discussing your experience say why you did it
or what you have learned from it.
Be honest and specific – only write things that you
would be prepared to discuss in an interview.
http://bit.ly/ucasmap
(pdf)
Polishing off
1. Up to half of the statement
can be reasons for your choice
of course.
2. Don’t use repetitive language
eg ‘I like’.
ISTOCKPHOTO
Handy tips
Good spelling and grammar is essential – don’t rely on
a spellchecker.
Structure is important. Begin with why you want to
study your subject and finish with why you want to go
university, or your career aspirations.
Show your statement to other people you trust and
make changes.
Expect to produce a number of drafts!
It can seem quite daunting to sit down to write your
UCAS personal statement. Don’t worry, if you write it in
stages and follow these guidelines, you should make a
positive impression on any admissions tutor who reads
it. Remember, the golden rule is quality, not quantity.
3. Avoid using clichés.
Getting started
4. No formatting is allowed by
UCA S (except capital letters) so
any bold, italic or underlined
words will disappear!
Write your statement offline in Microsoft Word and
save it regularly. When you are finished, paste it
into the online UCAS form. The form times-out after
35 minutes, so this will help to avoid losing any of your
precious work.
The aims of a personal statement are to show the
admissions tutor why you should be accepted on your
chosen course.
Read some examples of good personal statements, but
do not copy them as UCAS uses a plagiarism checker.
Make a rough list in three sections:
1. Reasons for choosing the course
2. Personal achievements and relevant experience
3. Hobbies and interests that show your skills
and abilities.
5. When working online
remember to regularly save
your work as UCA S Apply
will time -out after 35 mins
of inac tivit y.
6 | The Mole | July 2012
0412MOLE - Pages 4-11.indd 6
Choosing your chemistry course
The university you choose to study chemistry at is
important. It needs to be an informed choice and suit
what you hope to achieve. Check university and college
prospectuses, websites and entry profiles. These will
tell you the criteria and qualities universities want their
students to demonstrate. Finding the answers to these
questions should help you to focus:
If the course is not pure chemistry how much chemistry
is there relative to the other subjects throughout the
degree? Eg is there a difference between ‘Chemistry
and....’ and ‘Chemistry with....’ courses?
How much maths/physics support is there if I need it?
How many hours are spent in the teaching lab?
Is there a choice of modules to study? Do they
interest me?
What is the format of practical work in the final year ie
what is the amount of independent research compared
to other lab based activities?
Can I do an external placement?
Will this course help me to develop transferrable skills?
www.rsc.org/TheMole
6/11/2012 3:20:42 PM
University lectures
Top tips
for success
What should you expect and how can
you get the most from them?
Get a head start
Use the course handbook
to see what is coming and
read ahead. Make full use
of pre-lecture notes and
downloads.
Catherine Smith helps guide you through the transition
from school to university learning
Let’s start by looking at what happens in a lecture.
The format is surprisingly flexible and the content and
style will depend on the individual lecturer. Material
may be presented using PowerPoint or a tablet PC
or the lecturer may simply talk, perhaps making
odd notes on a whiteboard or blackboard. In most
cases lectures will be accompanied by some form of
handout. These may contain copies of the PowerPoint
slides, perhaps containing blanks for you to make
notes as the lecture progresses.
ISTOCKPHOTO
Initially, you will find it difficult to know whether simply
to sit and listen or to write copious quantities of notes.
This is a personal thing. What is important is that you
actively engage with the content. Learning is not a
passive activity and by being in the lecture theatre, the
knowledge does not simply diffuse into your brain! As
you listen, challenge what you are hearing. Link the
material to your previous knowledge on the subject.
Does it make sense? Do you agree?
What next?
The end of the lecture is just the start of the learning
process. At school, most of the learning happens in
the lesson, at university the lecture is where it begins.
Workshops, labs and tutorials add to your learning but
The first university lectures were delivered in medieval
it is equally important that you work independently as
times. The lecture was little more than reading a book
in front of others. It represented a practical and efficient well. As soon as you can after the lecture, you should
way to distribute information at a time when books were review your notes.
both rare and expensive.
In many departments you will find reading material,
resources, maybe even video recordings of the lecture on
You will be pleased to know that lectures have moved
the university’s virtual learning environment. Make use of
on somewhat since then. Unfortunately however, they
these. If you are not sure where to start, try highlighting
do still represent an efficient means of transferring
key phrases from the lecture and look these up in
information from teacher to learner.
the recommended textbooks. This will give you more
Welcome to lectures!
information and examples beyond the lecture material.
Lecture sizes vary hugely depending on course and
If all this sounds scary, don’t worry. Your university is
institution, so don’t be surprised to find another two
very aware of the challenges the new environment and
hundred freshers in your first lecture. In these big
way of learning presents to you. In the first few weeks,
lectures, the lecturer can’t possibly interact with you as
most departments provide workshops on key study
an individual as well as your school or college teacher
did. It is now very much up to you to be responsible for skills. Look out for these and make sure you attend,
even if it means missing a party!
your own learning. But what does this mean?
www.rsc.org/TheMole
0412MOLE - Pages 4-11.indd 7
Be active in your
learning
Think critically and
challenge your
understanding. Don’t be a
lecture sponge!
Remember the lecture is
just the beginning
Develop your
understanding by reading
around the subject and
applying the learning to
other contexts.
ok to
Remember – it's
ask for help!
ay look busy,
Although they m
will always
university staf f
struggling,
e
help. If you ar
ask for help as
u
yo
make sure
le. Don’t leave
soon as possib
te.
it until it’s too la
July 2012 | The Mole | 7
6/11/2012 3:22:05 PM
Cutting-edge chemistry
Did you
know?
Plants like ferns and
mosses (as well as bacteria
and fungi) produce spores
to reproduce – this is a
form of asexual
reproduction. The spores
are often adapted so that
they can be dispersed
some distance away and
survive for very long
periods of time.
Plant spores mop up oil
Scientists in the UK have modified plant spore
microcapsules to take up to three and a half times their
own weight in oil by a simple mixing process, giving
them potential as natural oil-spill clean-up materials.
Microcapsulation
Grahame Mackenzie at the University of Hull and
colleagues at Sporomex, a company that deals in microencapsulation for the pharmaceutical, food, cosmetics
and personal care industries in Hull, extracted the
outer layer of Lycopodium clavatum (clubmoss) spores,
removed the inner contents using a simple, non-toxic
process and modified the surface functional groups
to make them more soluble in oil. They then put the
microcapsules into an oil in water emulsion, shook it by
hand for 15 seconds, and filtered the microcapsules out
to leave an oil-free sample. The microcapsules could be
used two or three times without a change in oil recovery
efficiency, which the team attributed to the high
strength of the naturally occuring sporopollenin polymer
in the spore walls.
Rapid recovery
‘The advantage over conventional methods, for example
phase separation paper or simple solvent extraction, is
that the emulsion is simply mixed with the shells and
then filtered, which is more rapid,’ says Mackenzie.
Compared to other oil recovery methods, he says, ‘the
spores are a natural material, are very robust and have a
consistent size, making them easy to filter’.
Sporopollenin is also known to be very elastic and
so the group tested the release of oil from the
microcapsules under prolonged friction. They found
that the oil could be released slowly over short time
periods, indicating that the microcapsules could be
used as delivery vehicles in the pharmaceutical and
cosmetic industries.
No solvent required
‘A major breakthrough is the ability to evacuate the
spores without toxic solvents,’ says Miriam Rafailovich,
an expert in nanoscale materials engineering at Stony
Brook University, US. However, she says that ‘since
these spores can be allergens in their native form, the
interactions of these processed capsules with higher
organisms will need to be tested’.
Mackenzie considers one drawback to be ‘the high
cost and lack of large-scale availability’ of the spores,
however he adds that ‘research is ongoing and
applications are being explored by various companies’.
Thibaud Coradin of the materials and biology team at
the College of France in Paris says that the approach
‘should be highly inspiring for the future identification
and processing of biocapsules’. Lucy Gilbert
Find out more
dispersants
Traditional oil
surfactants;
are made from
ch are soluble
molecules whi
water. Find
in both oil and
t surfactants
ou
out more ab
rg/CWsurf
at w w w.rsc.o
A fish oil in water emulsion
before (left) and after
(right) introduction of the
plant spore microcapsules.
The microcapsules were
able to recover 98% of the
oil from the emulsion.
8 | The Mole | July 2012
0412MOLE - Pages 4-11.indd 8
www.rsc.org/TheMole
6/11/2012 3:22:29 PM
X-rays uncover hidden self portrait
Did you
know?
Nanoparticles can be used
to restore and preserve
ancient works of art
www.rsc.org/CW06091001
A collaboration between scientists and art historians
in Australia has uncovered a lost work of art by one of
the country’s most famous artists. But rather than lying
neglected in a dusty attic, this work was hidden under
nothing more than a layer of paint.
Seeing is believing
The use of x-rays to see the unseen is well known. Our
own bones absorb x-ray radiation, so medical x-rays can
effectively strip away our flesh to reveal our skeletons.
In the same way, x-ray radiography has been used to
look at works of art, uncovering hidden works where
artists have reused their canvasses, painting new over
old. ‘However, these techniques have their limitations,’
says David Thurrowgood, senior conservator at the
National Gallery of Victoria, Australia, ‘particularly when
large amounts of lead or other heavy elements prevent
visualisation of the layers underneath.’ Unfortunately,
such elements are extremely common when artists have
applied a white, often lead-based, layer to begin afresh.
Conventional radiography is then unable to penetrate
the lead-lined tombs of such lost works.
Hidden secrets
To solve this problem, Thurrowgood and collaborators
employed x-ray fluorescence, using x-rays produced at
the new Australian synchrotron facility in Melbourne.
Exposed to this radiation, the paint fluoresces – each of
its component elements emitting a unique signal that
can be detected and used to recreate the underlying
image. This also enriches the quality of the data says
X-ray fluorescence was
used to reveal a hidden
portrait in the painting
'Patch of Grass' by
Vincent van Gogh
Deborah Lau, one of the collaborators and a programme
leader at the Commonwealth Scientific and Industrial
Research Organisation (CSIRO) in Victoria. ‘X-ray
fluorescence allows an appreciation of the different
colours and paint composition,’ she explains. The
technique was pioneered by Koen Janssens at the
University of Antwerp, Belgium, who has used it to
reveal hidden works by Vincent van Gogh.
A rare treat
The painting in question is a self-portrait by Arthur
Streeton, who was, fittingly enough, a native of Victoria.
‘Streeton is one of Australia’s most loved artists,’
says Thurrowgood. ‘He painted very few portraits and
this was an opportunity to uncover a very rare self
portrait.’ The technique also reveals other secrets, he
adds. ‘In this case, we can see changes in [Streeton’s]
composition and his painting methodology...
understanding drawn from this painting will impact how
we look at other parts of the collection.’
One of the instruments used to investigate the
'Patch of Grass' oil painting
www.rsc.org/TheMole
0412MOLE - Pages 4-11.indd 9
These new insights demonstrate that this marriage of
science and art is coming of age says Janssens. ‘At the
moment, we are still in the scientific world, publishing
papers on improving the technique,’ he says. ‘But the
first art history papers are now coming out.’
Philip Robinson
Have a
closer look
Take a closer look at the
images produced by the
component elements to
see how the scientists put
together the final image
http://bit.ly/IKQrPc (pdf)
Find out more
about the
Find out more
t with this
chemistr y of ar
m the RSC
fro
ck
resource pa
l Gallery
and the Nationa
rt
Chemistr yofA
w w w.rsc.org/
July 2012 | The Mole | 9
6/11/2012 3:22:50 PM
Did you
know?
The oldest living tree in
the world is Methuselah,
a bristlecone pine tree in
the White Mountains,
California, US. In 1957
scientists measured it to
be 4600 years old.
On-screen chemistry
Tree of life – life, the universe and
everything
Jonathan Hare takes a look
Tree of Life1 is the haunting
story of life in 1950’s Texas
and a family’s struggle
to come to terms with
the death of a loved one.
However, embedded
within the film are also
a series of short, yet
stunningly beautiful, visual
explorations of crucial
events in the world’s
evolution. Ultimately
the film is about birth,
growth, death, religion and
evolution.
In these ‘visions’ we go
back thousands of millions
of years to witness the
formation of stars. We
see tiny planets come
together to form the Earth.
Simple molecules develop,
leading to the oceans and
more complex structures.
Primitive cells emerge
and we see something
akin to bacterial division
taking place. Sea creatures
move onto land, dinosaurs
appear, an asteroid falls to
Earth...
The chemistry of life
A bristlecone
pine tree in the
White Mountains,
California, US. One
of the oldest living
trees in the world
10 | The Mole | July 2012
0412MOLE - Pages 4-11.indd 10
In the lab
In 1952 Stanley Miller and Harold Urey, scientists at the
University of Chicago, US, wanted to investigate how the
basic building blocks of complex biological molecules
might have been created on the early Earth. They set
up a sterile glassware apparatus and added water,
methane, ammonia and hydrogen to represent the
Earth's early atmosphere (it is thought that an oxygen
rich atmosphere appeared much later). To simulate
lightning in the primitive Earth’s atmosphere an
electrical spark was continuously maintained.
What they found surprised them. Within a day the flask
had turned pink. In one week 10% of the carbon had
been converted to organic compounds. Even in this
short time quite large and complex molecules had been
created, including sugars, lipids and simple amino
acids such as glycine. In 2007 a box of some of the
original samples were rediscovered. Modern analysis
has revealed an even greater range of structures to be
present, including many amino acids.3
Possible reactions
From the starting materials there are many potential
reactions. For example, this is one route to the
formation of glycine:
H2O  H2 + O
(eg by UV radiation)
CH4 + NH3  HCN + 3H2
CH4 + 2O  CH2O + H2O
CH2O + HCN + NH3  NH2CH2CN + H2O
NH2CH2CN + 2H2O  NH3 + NH2CH2COOH (glycine)
.
.
The film does not go into these technical details.
However, what we see, beautifully presented in these
haunting scenes, is an intriguing and unique Hollywood
account of Earth’s evolution.
Perhaps the most important
of all the epochs is when life
first emerged from the early References
seas – sometimes called the primordial ‘soup’. What do 1. Tree of life, 20th Century Fox, 2011
2. M J Benton, The history of life: a very short introduction.
we know about the chemistry of this stage?
Oxford, UK: OUP
The first ‘life’ might have been very different from
J Keosian, The origin of life. Chapman & Hall
today’s simplest cell or bacteria. Current thinking is that
The TNA world before RNA, Chemistry World, February
once a suitably complex molecule formed – one that
2012 (http://bit.ly/CW080112)
could copy and replicate itself – then essentially life had 3. Miller’s legacy: new clues to origins of life, Chemistry
also started.2
World, October 2008 (http://bit.ly/CW161008)
www.rsc.org/TheMole
6/11/2012 3:23:09 PM
Judith Gregory
Procter & Gamble
Judith Gregory is a senior perfume
chemist at Procter & Gamble.
Josh Howgego finds out about her
work, career and finely tuned nose.
You might say that Judith Gregory’s job stinks; which
would be accurate but a little unkind. As a senior
scientist in the analytical fragrance department at
Procter & Gamble (P&G), Judith has to deal with some
lovely – and not so lovely – fragrances.
‘It sounds odd, but one of the favourite things I like
working with – purely because of the amount of
comments I get – is artificial sweat’ Judith tells me.
‘To me it doesn’t smell that bad – I think of it as like a
slightly overripe grapefruit.’
I am not at all convinced about Judith’s sense of smell,
but she assures me that she is what is referred to as
a ‘trained nose;’ having been trained up over the past
decade or so to understand the subtle nuances of
perfumes. This is important in her role, since she is part
of a team responsible for developing the fragrances
which go into a whole raft of up-and-coming products
in the P&G pipeline. ‘One of the products we’re working
on right now is a perfume for an Italian jeans label called
Replay,’ says Judith.
Most of the work she does is about experimenting to
get the right mix of chemicals into the final perfume.
Different odorants (smelly chemicals) evaporate from
the skin at different rates, depending on several factors
including their molecular weight. A perfume is made
up of hundreds of different individual molecules, to
form a rich and complex aroma. Judith’s team use
analytical techniques such as gas chromatographymass spectrometry to characterise which molecules
will evaporate (and be smelt) over the course of the
day. Ideally different scents should be evaporating
throughout the day to give a sense of the perfume
‘working’ for a long time.
Odd (and amazing) olefaction
In fact olfaction – the sense of smell – isn’t really all
that well understood. P&G do in-house research and
fund universities to explore more about how molecules
interact with our noses and produce the sensation
of smell. Judith cites the example of limonene, the
molecule that smells of lemons. ‘You have to have really
quite a lot of it in a formulation to be able to smell it. But
put a tiny drop on your tongue and – whoompf – you’ll
know about it.’
Judith also works with cyclodextrins – large, hollow
molecules which can encapsulate odorant molecules.
Because they’re water soluble, when someone wearing
the perfume sweats, the water dissolves the cyclodextrin
and releases a fresh waft of scent just when you need it.
‘We call it high-impact fragrance,’ says Judith. The teams
have to use artificial sweat to understand if the released
odour effectively masks the smell of body odour.
Nifty skills
As in nearly all jobs, team working is an incredibly
important skill for Judith. ‘The analytical department is a
global organisation, so I work with colleagues in the USA
and I’ve previously spent quite a bit of time in Brussels.
You just have to have good team working skills to be
able to properly discuss what you’re doing and keep up
to date with each other.’
Time management is also vital, as experiments are
often time sensitive. Judith is often in her laboratory at
07.30 in the morning to get experiments started, but the
company’s flexitime policy means that she can fit the
experiments around her personal life.
Judith began work at P&G just over 20 years ago,
straight after her A-levels, and has obtained her degree
through a day release scheme with P&G. She’s now
a manager in her own right, but enjoys the fact that
she has options in terms of career progression. She’s
chosen to pursue the path of staying in the lab and
mentoring other staff on an informal basis. ‘There’s less
paperwork that way!’ she exclaims.
Mole
You can download The Mole at www.rsc.org/The
and copy it for use within schools
www.rsc.org/TheMole
0412MOLE - Pages 4-11.indd 11
Pathway to
success
2010–present
Senior scientist, Analytical
Prestige Fragrance &
Perfumery Group
2006–2010
Scientist (subsequently
senior scientist),
Analytical Beauty Care
Fragrance Group
1995–2006
Scientist, Analytical Health
Care Group and
subsequently Fragrance &
Perfume Group
1991–1994
Researcher (subsequently
senior researcher),
Analytical Oral and
Hair Care Groups
1992–1995
BSc(Hons) chemistry at
Kingston University
(studied on day release
whilst working at P&G)
1990–1992
HNC chemistry at
Kingston University
1990–1991
Researcher, Analytical Health
Care Respiratory Group,
Analytical Department,
Procter & Gamble
1988–1990
A levels in chemistry,
biology, geography,
Tomlinscote 6th Form
College, Frimley, Surrey
Find out more
out the
Lear n more ab
agrances and
fr
chemistr y of
orld's most
some of the w
rf ume
celebrated pe
at
es
ul
ec
mol
/C Wscent
w w w.rsc.org
July 2012 | The Mole | 11
6/11/2012 4:02:57 PM
£25 of vouchers to be won
Puzzles
Wordsearch
Find the 33 words/expressions associated with chemical bonding
hidden in this grid (contributed by Bert Neary). Words read in any
direction, but are always in a straight line. Some letters may be used
more than once. When you have found all the words, use the remaining
letters to make a 9-letter word.
ANIONS
AGGREGATES
ATTRACTION
CATIONS
CLOUD
CORES
COVALENT BONDING
ELECTRICAL BINDING
ELECTRON PAIR
ENERGY
GAS
IONIC
IONIC BONDING
IONS
INTERMOLECULAR
LABORATORY
LATTICE
MOMENTUM
NEUTRAL
NEUTRON
NUCLEI
NUCLEONS
NUCLEUS
PATTERNS
PHYSICAL FORCES
POLAR BONDING
PROTON
REACTIONS
REPULSION
SHELLS OF ELECTRONS
SOLID
SOLVATION FORCES
SPHERE OF CHARGE
May puzzle solutions and winners
The winner of the wordsearch puzzle was Kirsty Barber from Colchester.
The 6-letter word was HOCKEY. The acrostic puzzle was won by Daniel Zheng
from London. The 12-letter word was TESTOSTERONE.
Dates for your diary
RSC ChemNet Events
RSC ChemNet events are supported by an
education grant as part of the Reach and
Teach program funded by the Wolfson
Foundation.
Pathology laboratory tour
2 July 09:30–13:00
Norfolk & Norwich University Hospital,
Norwich
http://bit.ly/GTO7p1
Discover chemistry day
2 July 09:45–15:30
University of Manchester
http://bit.ly/L82ZOP
University laboratory session
11 July 16:00–19:00
Newcastle University
http://bit.ly/MrHGpk
What’s it like to study chemistry at
university?
18 July 10:00–16:00
Newcastle University
http://bit.ly/LBkxjw
0412MOLE - Puzzles_Revised.indd 1
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by Monday 16 July.
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Shedding light on the past –
chemistry in the museum
28 August 16:30–19:00
University of Glasgow
http://bit.ly/Nm1XSt
BASF – science in action /
industry visit
30 October 09:00–13:00
BASF Performance Products, Bradford
Learn about the chemistry of polymers
http://bit.ly/LBl7xv
Comet chemistry
17 November 10:00–15:00
National Space Centre, Leicester
http://bit.ly/GWEwHx
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