SPECIALTY POLYMERS

Prof. Andrzej W. Trochimczuk

Laboratory of Polymer and

Carbonaceous Materials

Faculty of Chemistry

Wroclaw University of

Technology

•Building H6 room 110, Wt i Czw 11.15-
13.00

SPECIALTY POLYMERS

• In this introductory lecture we will try to

define the basic terms in polymer chemistry

• To find out how apparently small changes in

polymer chemistry of physical structure
make these polymers unique

• Try to find out how polymers are so

different when compared to other classes of
materials

SPECIALTY POLYMERS

•What are the polymers?

•Molecules that are formed by linking of the
repeating units through covalent bonds
•MW below 1000 Da, 1000-10 000 and >10 000
•Properties are determined by:

•molecular weight
•backbone structure
•side chains presence and position
•crystallinity

•Macromolecules have huge molecular weights
(up to few millions Da)

SPECIALTY POLYMERS

Polymers

are large molecules made up of repeating

units called

Monomers

The synthetic process is

Polymerization.

E.g.

Monomer

Polymerization

Polymer

Monomer

Polymerization

Polymer

Note – define repeating unit in terms of monomer structure

Degree of Polymerization

is the number of monomer units in a Polymer

However, for synthetic polymers it is more accurate to state

average degree of polymerization ( ¯ )

SPECIALTY POLYMERS

•The use of average degree of polymerization is a must
because in one batch of synthesis you obtain molecules
of different size

•This feature is

unique to polymers!

SPECIALTY POLYMERS

• number average,

• weight average, M

: # of molecules with degree of

polymerization of i

: molecular weight of i

SPECIALTY POLYMERS

• Ratio of M

to M

is known as the

polydispersity index (PI)

– a measure of the distribution of the

molecular weight

– PI = 1 indicates M

= M

, i.e. all

molecules have equal length

(monodispersive polymer)

– PI = 1 is typical for some natural

polymers, whereas synthetic polymers

have 1.5 < PI < 5

– At best PI = 1.05 can be attained with

special techniques

SPECIALTY POLYMERS

• Asymmetric substitution pattern of

most monomers

• Addition may not be completely

regiospecific

; not 100% head-to-tail

X Y

Y X

head-to-head

tail-to-tail

C C

C O
OH

tail

head

SPECIALTY POLYMERS

• Isotactic:

all side groups in one side of main

chain zig-zag

H R

Syndiotactic:

side groups alternating

R H

•Atactic:

side groups in random

order

R H

H R

R H

H R

SPECIALTY POLYMERS

• Polymers can be either

amorphous

semi-crystalline

• Tacticity

, i.e. arrangements of substituents

around the backbone, determines the

degree of crystallinity

• Atactic polymers are amorphous

• Isotactic and syndiotactic may crystallize

• Crytallinity depends on:

– size of side groups (smaller,

↑crystallinity)

– regularity of chain

• Increased crystallinity enhances

mechanical properties

• Amorphous
• Semi-crystalline
• Crystalline

SPECIALTY POLYMERS

•Mesophas
e, another
feature
characteris
tic for
polymers

Polymers

• Common topologies of polymers

linear

branched

crosslinked

Polymers

• Common topologies of polymers

(cont.)

star

ladder

comb

Polymers - suspension

Bad solvent

induces

early phase
separation, chains
try to interact with
each other. High
chances of
crosslinking.

Good solvent

‘’separates’’ chains
thus delaying phase
separation. Even
distribution of chains
in a droplet – no
cavities.

Polymers - suspension

Polymerization

Removal of

Porogen

Phase separation

Polymers - suspension

polymerization

phase separation

monomer(s)

porogen(s)

porogen removal

Polymers - suspension

• The above was

possible only due
to the presence of
sufficient amount
of the

crosslinker

• What happens

when there is no
crosslinker?

C
O

Polymers - suspension

•

Structure of gel and

macroporous type polymer

Gel-type polymer beads

- clear and glass-like

- lightly crosslinked(~

2%)

no surface area in dry

state

-swells in good solvents

modification up to ~

100%

possible

Macroporous resins

-opaque

-highly crosslinked(>

20%)

permanent pore and

high surface area

-pores accessible to

all

solvents

-modification limited

ca.30-40%

Polymers - suspension

Schematic representation of various agglomerates in

macroporous copolymer network

The smallest

particles are

called

called nuclei

nuclei

The nuclei

are nonporous

and consitute

the highly

crosslinked

regions of the

network.

Micropores

defined with

widths of up to

2 nm appear

between the

nuclei

Polymers – suspension

•

The agglomerations of nuclei are

called

called microspheres

microspheres

. Mesopores

Mesopores

are between the microspheres.

•

Microspheres are agglomerated

again into larger

again into larger irregular

irregular

moieties

250~1000 nm inside the polymer

material.

material. Meso and macropores

Meso and macropores

appear between the

agglomerates of the

microspheres.

Polymers – suspension

• Porous polymers

are used mainly as
adsorbents and
mainly as obtained
from suspension
polymerization

• Gel polymers are

used mainly as ion-
exchangers,
chelating resins,
support for organic
syntheses. In most
cases they have to
be modified after
suspension
polymerization.

Polymers – suspension

O H

In the synthesis of
adsorbents

In the synthesis of gel
type polymers

SPECIALTY POLYMERS

• Thermoplastic

– polymers that flow

when heated

– easily reshaped

and recycled

– due to presence of

long chains with

no crosslinks

– polyethylene,

polyvinylchloride

• Thermosets

– High

crosslinking

when heated

– can not be reformed

or recycled

– presence of

extensive crosslinks

between long chains

– induce

decomposition upon

heating and renders

thermosetting

polymers brittle

– epoxy

SPECIALTY POLYMERS

• Elastomers

– some crosslinking

– can undergo

extensive elastic
deformation

– natural rubber,

silicone

– intermediate

between
thermoplastic and
thermosetting
polymers

• Our specialty

polymers can
belong to any of
these groups

SPECIALTY POLYMERS

•Are they important?
•Reasons for their
presence everywhere
•Annual production
worldwide

1,5x10E11

•(120 years ago was
almost 0)
•Annual ‘production’
in nature

4x10E14 kg

•Now, when we know a little bit about
polymers

…

CZŁOWIEK

MATERIAŁY

Populacja

[mld]

~100 tyś.

~100 000 p.n.e.

10 mln

4 000 p.n.e

100 mln

750 p.n.e.

200 mln
400 n.e.

1600 n.e.

600 mln

1 mld

1820 n.e

6 mld

~2000 n.e.

TECHNOLOGIE

Półprzewodniki

Ceramika

Materiały

syntetyczne

Stal

Aluminium

Zn, Pb, Au, Ag

Szkło

Brąz

Mosiądz

Żelazo

Kamień

Drewno

Glina

-1.85 mln

Australopitekus

-500 000 -100 000 -35 000

Neandertalczyk Homo sapiens

-8 600

-4 000

1700

1000

1800

1900

2000 rok

Nauki przyrodnicze

Nauki techniczne

Nauki społeczne

Inżynieria materiałowa

Maszyna

parowa

Samochód

Samolot

Komputer

Socha

Ogień

Koło

Naczynia

Narzędzia

kościane

Narzędzia

kamienne

Zwiazek miedzy wzrostem populacji ludnosci i dostepnoscia materialów oraz

ich wykorzystaniem do wytwarzania narzedzi i jako surowce we wspólczesnych procesach technologicznych

SPECIALTY POLYMERS

1940

1950

1960

1970

1980

1990

120

150

-9

/ k

Year

•Worldwide Polymer
Production

•Commodity
polymers

•Engineering
polymers

•Specialty
polymers

SPECIALTY POLYMERS

•Our
intere
st

SPECIALTY POLYMERS

• And here comes the question – what really

is a specialty (reactive) polymer?

• The is no definition and since the reason

for the syntheses of specialty polymers is
the dissatisfaction with the role given to
the „ordinary” polymers and the desire to
add sophisticated function to polymers we
can conclude that all materials except
commodity and construction polymers are
specialty ones.

SPECIALTY POLYMERS

• This desire to add sophisticated function to

polymers was present from the very start

of the polymer science

• History of polymer science is very young

but dynamic and can be plotted as it was in

the case of technologies and materials

earlier in this lecture

• The appreciation of polymers resulted in

few Nobel Prizes

• “Polymeric Nobel

Prizes”

• 1953 Hermann

Staudinger

• 1963 Giulio Natta,

Karl Ziegler

• 1974 Paul J. Flory
• 2000 Alan J.

Heeger, Alan G.
MacDiarmid,
Hideki Shirakawa

• Polymer science

separate branch of

science can be dated at
the end of XIX century.

• From that time the use

of polymers become so
popular that their
production in XX century

increased ca. 800
000%

• The

participation of

specialty

polymers in

the total production is
growing.

•SPECIALTY POLYMERS

SPECIALTY POLYMERS

• Prof. Hermann Staudinger (1881 - 1965),

Univ. of Freiburg, Germany. Started his

carrier in Federal Institute of Technology,

Zurich, Switzerland. Professor of organic

chemistry, known for his work on

diazomethane. Ca.1920 decided to shift his

scientific interest and devoted his time to

macromolecules. This decision brought him

Nobel Prize and fame, but had to be very

difficult.

• Among chemsits the idea of macromolecules

was not popular. For example Heinrich

Wieland (Nobel 1927) wrote to Staudinger ‘…

forget the idea of macromolecules, organic

molecules with MW bigger than 5000 simply

do not exist. Try to purify rubber and it will

crystallize then.’

SPECIALTY POLYMERS

• Another Nobel Prize winner - Paul Carrer

(Nobel 1937) for many year was saying that
‘…cellulose, starch, proteins and rubber are
aggregates of molecules, displaying ‘colloidal
character’’. And vast majority of chemists
used the term ‘chemistry of grease’ talking
about experiments with compounds, which
can not be purified neither by distillation nor
by crystallization.

SPECIALTY POLYMERS

• Prof. Giulio Natta

(1903 - 1979), Institute of

Technology, Milan, Italy. Before polymers he was
working in crystallography and heterogeneous
catalysis. From 1954 experiments on polymerization
with the use of Ziegler’s catalysts led to the
semicrystalline polymers (PP, PS, poli α-butylene), he
also worked of stereoregularity and crystallinity of
polymers.

• Prof. Karl Ziegler

(1898 - 1973), Max Planck

Institute for Carbon Research, Mulheim, Germany. The
research on anionic polymerization of butadiene was
carried out in 1928-1934, and using butyllithium in
50’. He discovered that ethylene can attach itself to
this compounds, thus increasing the length of alkyl
chain. This chain can be abstracted from the catalyst
giving α-olefines and LiH. Further work resulted in the
discovery of metalloorganic catalysts used in the
production of low density PE.

1940

1950

1960

1970

1980

1990

120

150

-9

/ k

Year

SPECIALTY POLYMERS

•Their work had the vast influence on polymeric materials –
stereoregularity ~ crystallinity ~ mechanical properties

SPECIALTY POLYMERS

• Professor Paul J. Flory (1910 - 1985), Stanford Univ.,

USA. Started his work in the R&D laboratory of

DuPont, Delaware, USA. He investigated the kinetics

and molecular weight distribution in polycondensation

processes, Described the gelation in multifunctional

monomer polymerization, worked on theory of

polymers in solutions, conformation of polymeric

chains and their hydrodynamic properties.

SPECIALTY POLYMERS

• Professor Alan J. Heeger (1936), Univ. of California,

Santa Barbara, USA. PhD in theoretical physics from

UCB. Work in the Dept. of Physics Univ. of

Pennsylvania included physics of molecular crystals,

from 1975 poly(sulfur nitride), a year later

polyacetylene (brought from Japan by H. Shirakawa).

• Professor Alan J. MacDiarmid (1927), Univ. of

Pennsylvania, USA. MSc from Univ. of New Zealand,

PhD from Univ. of Wisconsin and from Cambridge

Univ., works in conducting polymers (synthesis,

doping, electrochemistry, their magnetic and optical

properties).

• Professor Hideki Shirakawa, Tsukuba Univ., Tsukuba,

Japonia. B.S, MSc and PhD from Tokyo Institute of

Technology. Investigations of the mechanisms of

polymerization on Ziegler-Natta catalysts using

acetylene as monomer. In 1967 he succeded (by

chance!) in obtaining polyacetylene in the for of a

film. In 1976/77 comes to Univ. of Pennsylvania and

works on the chemical doping of polyacetylene.

•Obtained
using Ziegler –
Natta catalyst
•Trans form is
the stable one
•Attempts to
graphitize
polyacetylene

SPECIALTY POLYMERS

•New polymeric
systems are
investigated
•Those polymers
are used in
photovoltaic units,
luminescent diods
•Possible
superconductivity

SPECIALTY POLYMERS

•Finally, after
doping it was
possible to
increase the
conductivity to the
level of metals

•Pure polyaniline
is an insulator,
polyacetylene is an
semi conductor

•SPECIALTY POLYMERS

C C

( ) ( )

m n

•Conducting polymers
can be further
modified

•Pendant groups can
be selected in a way
to perform specific
task

•Here, the
organometallic ring
can contribute to the
conductivity of the
main chain

Permeabili
ty for
gases

conductivi
ty

Complexin
g

attachemen
t

SPECIALTY POLYMERS

• Ion separation

• Elution of various

cations is
different,
depending on
their affinity to
the crown ether

SPECIALTY POLYMERS

•Sometimes it is
enough to
synthesize
known polymer
(polyamide) in a
way that
interchain
interactions are
maximized

SPECIALTY POLYMERS

• Hip joint socket –

stiff, strong, wear
resistant and low
friction -UHMWPE

•UHMWPE – ultra high
molecular weigth PE
(ca. 6 mln Da)

•So, from chemical
point of view is just as
PE used in the
sandwich bags

SPECIALTY POLYMERS

•Our
interest in
specialty
polymers

SPECIALTY POLYMERS

• The „specialty” of the polymer is

determined by the property given to
it when synthesized for a particular
application

• Even a small change in chemical

and/or physical structure can cause
the „upgrade” of the polymer from
commodity or engineering to the
specialty class.

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