Wallace
Hume Carothers
(1896 - 1937)
synthesised
polychloroprene and polyesters
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Wallace Carothers was born on April 27th 1896,
the eldest of four children, in Burlington, Iowa.
He was considered ‘bookish’ at school
but that was to underestimate his breadth of
interests. As well as devouring every book he
could get hold of he was fascinated by mechanical
toys and he loved music, his tastes ranging from
Bach to Gilbert and Sullivan. In high school his
interests turned to chemistry and he built a
laboratory in his bedroom.
His father taught at Capital City Commercial
College in Des Moines and it was here that
Carothers went to study accounting when he left
school. He then moved to Tarkio College in
Missouri to study chemistry although, being short
of funds, he used his accounting learning to
advantage by teaching it in his spare time! He
must have been a remarkable student - possibly
unique - because he was made head of the
chemistry department WHILST STILL AN
UNDERGRADUATE. He graduated in 1920, obtained his
Masters in 1921 and his Doctorate from the
University of Illinois in 1924. He was then
appointed a professor at Harvard where he began
his serious research career into high polymers.
It was during his time in Illinois that the
tormented side of Carothers’ character
surfaced when he filled a phial with cyanide, to
be carried with him for the rest of his life as
an escape route if his fits of depression became
too much to bear.
In 1928 DuPont broke new ground by setting aside
a laboratory for pure research. The ‘Blue
Skies’ approach is not unusual today but at
that time corporate research was very much ‘cashflow
oriented’. The chance to forgo teaching and
devote all his time to research was not to be
missed and, at 32, he was placed in charge of
DuPont’s research division. It was known
that he suffered from moods of deep depression
and his staff was warned to look out for them but
his mentor, Roger Adams, believed that these
could be controlled and that Carothers had much
to give the world from his researches. He was
half right!.
Dupont was aware of the work of Father Julius
Nieuwland into the synthesis of chloroprene from
acetylene and believed that this could be the
precursor of a viable synthetic elastomer (chloroprene
has a molecular structure which can be described
as that of isoprene [the building block of
natural rubber] with its branched methyl group
replaced by a chlorine atom). This became
Carothers’ first project and in April 1930
the polymer was synthesised by one of his team,
Arnold Collins. This had the anticipated ‘rubbery’
properties and whilst these were somewhat poorer
than those exhibited by natural rubber in many
areas it had a much greater oil resistance. This
gave it a niche market and it went into
production in 1931 as Neoprene, the first
commercially successful synthetic polymer which
is still in production today. The chemical name
for the elastomer is polychloroprene, Neoprene
being DuPont’s trade name, but, like Hoover
the word has now been accepted as generic.
With that problem quickly resolved (three years
from start of research to commercial production!)
Carothers’ group turned its attention to
synthetic fibres, specifically to find a
replacement for silk which was in short supply
because of trade and political problems between
the USA and Japan.
He had postulated some years earlier that if an
acid and alcohol could condense, with the
elimination of water, to produce an ester, it
should be possible to make a giant molecule (polymer)
by linking diols to diesters. This was soon
achieved by one of his team, Julian Hill, to give
an early polyester but the physical properties
were too poor for commercialisation and Carothers
turned his attentions to polyamides, replacing
the diols with diamines. In 1934 the first
successful fibres were made. Carothers’ team
was working with over 100 different materials and
he identified them by two numbers, indicating the
number of carbon atoms in the diacid and diamine.
In February 1935 he polymerised adipic acid (C6)
and hexamethylene diamine (C6) to give speciman
66 which had good physical properties when it was
drawn into a fibre. The material was christened
Tiber 66 and, in September 1938 re-christened
Nylon66. In three years of research Carothers’
team had created the first commercial synthetic
rubber with the discovery of neoprene and now
they had done it in the plastics field with nylon.
Carothers’ immediate superior decided to hit
one market with this new product and in May 1940
nylon stockings hit the hosiery stores nationwide.
At just over one dollar a pair, five million
pairs were sold on the first day. When the States
entered the Second World War and arrived in the
UK, a few pairs of nylons could buy anything! By
that time however, production of nylon had been
directed towards the war effort, particularly
parachute canopies, rot-proof cords and life
rafts and the ladies had to wait a few more years
to have an unlimited supply of seamless or fully
fashioned nylon stockings.
The research work of Carothers and his team
changed the world but he couldn’t cope with
it even as it was and he never knew what he had
achieved. His earlier bouts of depression and
heavy drinking had destabilised him. He grew up
in a very close relationship with his sister,
Isobel, and then fell in love with a married
woman but, when she became available, he
retreated to his parents’ house. He spent
time in a psychiatric hospital and was advised to
marry by his doctor.
In January 1936 his sister died and soon after he
married Helen Sweetman, a co-worker at DuPont.
She and DuPont rapidly agreed that he needed
hospitalisation and after some treatment he was
released to take a walking holiday in the Alps
with his old friend Roger Adams. According to
Adams he seemed to improve during this time but
relapsed on his return to the US even though he
was actively cared for by his wife, psychiatrist,
friends and colleagues. In the middle of April
1937 Helen told him that she was pregnant and on
April 29th of that year, alone in a hotel in
Philadelphia, he cracked open his phial of
cyanide and died believing that he was ‘morally
bankrupt’ and that his work had been useless.
Helen later gave birth to a daughter, Jane.
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