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St ructure and Propert ies
of PolymersPolymer Physics I
Christopher Y. Li
Depart ment of Materials Science and EngineeringDrexel Universit y
ht t p:/ / w w w .mse.drexel .edu/ srg/
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The Future of PolymerScience
MATE 501: Structure and Properties of Polymers-CYL
Section 1
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MATE 501: Structure and Properties of Polymers-CYL
http://people.ccmr.cornell.edu/~cober/NSFPolymerWorkshop/index.html
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MATE 501: Structure and Properties of Polymers-CYL
1. Polymer Synthesis and New Polymeric
Materials2. Complex Polymer Systems3. Modeling and Theory
4. Characterization and Properties5. Processing and Assembly6. Technology and Societal Applications
Workshop Topics
http://people.ccmr.cornell.edu/~cober/NSFPolymerWorkshop/page13/page13.html
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MATE 501: Structure and Properties of Polymers-CYL
Develop the synthetic, analytical, theoretical/computational, and processingcapabilities needed to master the structural control provided by new polymersand processes. In order to achieve unparalleled science and engineering
breakthroughs, we must bring separate research disciplines together. A commontheme in all breakout groups was the tremendous need for theory and simulationsperformed in synergistic collaboration with researchers in synthesis,characterization, and processing to provide guidance for these efforts.
Be able to tailor-make polymers. New synthetic methodswith exquisite control over molecular structure and functionpossessing a precision rivaling biomolecules must bedeveloped if we are to provide the materials needed for exciting
future advances. In particular, new materials including complex,hybrid polymers with specific properties made in smallquantities will be needed for the future applications envisagedby this workshop.
Recommendations:
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Develop real-time, high throughput, non-destructive, in-situ,multiscale polymercharacterization techniques. Multiple,
simultaneous analyses will provide real time information of unrivalledprecision to enable the implementation of precision processing and usherin the use of new self-assembling materials.
Be able to process polymers and complex hybrid materials with 2Dand 3D structural control down to dimensions of a few nanometersusing both directed and self-assembly. Processing combined with newsynthetic polymers that undergo self-assembly will permit materials withthe molecular precision needed in emerging technologies. Using directed
and self-assembly in combination provides unprecedented opportunitiesfor tailored materials that must be explored.
Recommendations:
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Accelerate research in technology-focused, enabling polymermaterials. A common theme in the breakout sessions was the vital andgrowing role that polymers will play in the energy, life science,
microelectronics, and information and communications technology fields.The use of polymers will increase dramatically in areas traditionallydominated by inorganic materials as a result of fundamental opportunitiesprovided by the coupling of polymer synthesis, processing,
characterization and theory.
Enhance cyberscience for the purpose of sharing modelingmodules within the broad polymer community, and encourage thecreation of digital libraries of extensive data on polymer systems.
Increasing amounts of information and new cyberscience tools arebeing produced, but there are few efficient means to access them in anorganized fashion. Research and teaching would be boosted by improvedaccessibility to these new tools.
Recommendations:
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Section 2
To catch up background
MATE 501: Structure and Properties of Polymers-CYL
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MATE 501: Structure and Properties of Polymers-CYL
Outline: A few topics in condensed
state polymersIntroduction, Polymer concept, history, commercialpolymers
Polymer Chain Structure, helical conformation idealchain, real chain
Crystalline and Liquid Crystalline Polymers (Structure)
Amorphous Polymerspolymer chain structure, polymer morphology, polymerstructure, amorphous state, crosslinked polymer andrubber elasticity, and polymer surface and interfaces.
Experimental technique: Light Scattering, X-rayscattering, X-ray and electron diffraction, polymermicroscopy.
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Textbooks and beyond
Introduction to Physical Polymer Science, by L. H.Sperling, John Wiley & Sons, Inc. 4th ed.
Polymer Physics, Michael Rubinstein and RalphColby, Oxford.
Macromolecular Physics, Vol. 1, 2, 3, BernhardWunderlich, Academic Press Inc. 1973.
The Physics of Polymers, Concepts forunderstanding their structures and behavior, G.Strobl, Springer.
Fundamentals of Polymer Science, by Paul C.
Painter and Michael M. Coleman. Principle of Polymer Chemistry, Paul Flory, Cornell
University Press, 1953. Principles of Polymer Systems 5th ed. Rodriguez,
Cohen, Ober, Archer, Taylor & Francis
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Journals Macromolecules Polymer Journal of Polymer Science Advances in Polymer Science Progress in Polymer Science Macromolecular Chemistry and Physics Journal of Applied Polymer Science
Science, Nature Journal of American Chemical Society Physical Review (Lett.; B, E, etc.) ACS Journals Wiley RSC
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As Early as Life Began: natural polymers - BIOMACROMOLECULESPolysaccharides: DNA, RNA, starch, cellulose, chitin, etc.
What are Polymers?
A-DNA Loop RNA
Hemoglobin
Chitin
Proteins and Polypeptides Natural rubbers
Silk
Cellulose
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As Broad as in Daily Life: synthetic polymers
polystyrene cis-polyisoprene poly(vinyl pyrrolidone)
polycarbonate poly(vinyl chloride)
What are Polymers?Polymers are very large molecules that are comprised or built up of smaller units or monomers.
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Focus of This Course SYNTHETIC POLYMER!!!
Definition of Synthetic Polymers: Poly+ Mer= many + parts or units Long-chain-like molecules or macromolecules consisting of
many repeating units (monomers) that are covalently linked,instead of physically-associated aggregates Molecular weight higher than ~10,000 g/mol (different from
oligomers, which is composed of a few repeating units)
Synthetic Polymers - Definition
Natural Polymers Synthetic Polymers
Repeating units many kinds one or a few kinds
Structure well-defined poorly defined
MW distribution 1.0 for proteins from 1.0 to ~30
Differences between Natural Polymers and Synthetic Polymers
See Sperling Table 1.8 for commercialization dates of important polymers
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Molecular Weight and Molecular Weight Distribution
Molecular Weight Distribution:
Average Mn
= NX
MX
/ NX
,
Average MW = NXMX2/ NXMX Average MZ = NXMX3/ NXMX2 Polymer dispersity index PDI = MW/Mn = 1 ~ 10 or even more
Molecular weight distribution is a unique characteristic of polymers.
Broad molecular weight distribution could broaden the crystal meltingpeak.
x = MX/M0X, degree of polymerization
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Nobel Laureates in Polymer Science- Chemistry
1963 KARL ZIEGLER and GIULIO NATTA for their discoveries in the field of thechemistry and technology of high polymers.
Ziegler Natta
1974 PAUL J. FLORY for his fundamental achievements, both theoretical andexperimental, in the physical chemistry of the macromolecules.
Flory
1953 HERMANN STAUDINGER for his discoveries in the field of macromolecularchemistry.
Staudinger
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MATE 501: Structure and Properties of Polymers-CYL
Nobel Laureates in Polymer Science- Physics
1991 PIERRE-GILLES DE GENNES for discovering that methods developedfor studying order phenomena in simple systems can be generalized to morecomplex forms of matter, in particular to liquid crystals and polymers.
de Gennes
2000 ALAN J. HEEGER, ALAN G. MACDIARMID, and HIDEKI SHIRAKAWAfor the discovery and development of conductive polymers.
Heeger MacDiarmid Shirakawa
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The Nobel Prize in Chemistry 2005
"for the development of the metathesis methodin organic synthesis"
Yves Chau vi n Rober t H .
Grubbs
Richar d R.
Schrock
Institut Franaisdu PtroleRueil-Malmaison,France
CaliforniaInstitute ofTechnology(Caltech)Pasadena, CA,USA
MassachusettsInstitute ofTechnology (MIT)Cambridge, MA,USA
b. 1930 b. 1942 b. 1945
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the Charles Stark Draper Prize2002: Robert Langer
for the bioengineering of revolutionary medical drug delivery systems.
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Polymer Science and Engineering- A
Multidisciplinary Field
Chemistry Physics
Biology Engineering
MaterialsScience
POLYMER
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Step Growth vs. Chain Polymerization
Which is step growth? Which is chain polymerization?
step growth
chain polymerization
chain polymerization
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Step growth
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Chain Polymerization
Four Steps:Initiation, propagation, (chain transfer), Termination
Initiation
propagation
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Chain Polymerization: Termination
Combination
Disproportionation
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Chain Transfer
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History of Macromolecules and Polymers
1846Christian Schnbeininvented gun cotton
1862Alexander Parkes made
articles from plasticized cellulose nitrate
1870John and Isaiah Hyatt patented celluloid
1892Charles Cross, Edward
Bevan, and Clayton Beadlepatented regenerated cellulose,
i.e., viscose rayon fibers andcellophane films
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History of Macromolecules and Polymers
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History of Macromolecules and Polymers
1977Alan Heeger, Alan
MacDiarmid, and HidekiShirakawa discovered and
developed conducting polymers
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The power of MW
MATE 501: Structure and Properties of Polymers-CYL
See Sperling Table 1.4 and 1.6 for common polymers.
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MATE 501: Structure and Properties of Polymers-CYL
Solid Intermediate Liquid
Crystal
Mesophase
GlassMesophase Melt
GlassDisorder
Increasingorder
Immobile Increasingly mobile
Td
Tm
Ti
T
g
Tg
Possible phase t ransit ions in onecomponent system
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Polymer Chain Structure
MATE 501: Structure and Properties of Polymers-CYL
The conformation of the chains in space. The term conformation refersto the different arrangements of atoms and substituents of the polymerchain brought about by rotations about single bonds. Examples ofdifferent polymer conformations include the fully extended planar
zigzag, helical, folded chain, and random coils.
The molecular weight and molecular weight distribution of themolecules.
The configuration of the chain. The term configuration refers to theorganization of the atoms along the chain. Some authors prefer the
term microstructure rather than configuration. Configurationalisomerism involves the different arrangements of the atoms andsubstituents in a chain, which can be interconverted only by thebreakage and reformation of primary chemical bonds.
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isomerism
MATE 501: Structure and Properties of Polymers-CYL
Sequence Isomerism
Stereoisomerism
Optical Isomerism
Geometric Isomerism
Substitutional Isomerism
Head to Head and Head to
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Head-to-Head and Head-t o-
Tail Conf igurat ions
MATE 501: Structure and Properties of Polymers-CYL
head-to-tail
head-to-head
STEREOCHEMI STRY OF
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STEREOCHEMI STRY OF
REPEATI NG UNI TS
MATE 501: Structure and Properties of Polymers-CYL
Chiral Centers
Such carbon atoms are referred to as pseudochiral centers in long-chainpolymers because the polymers do not in fact exhibit optical activity
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Tact icit y in Polymers
MATE 501: Structure and Properties of Polymers-CYL
Three different configurations of a
monosubstituted polyethylene
Meso and Racemic
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Meso- and Racemic
Placements
MATE 501: Structure and Properties of Polymers-CYL
The Fisher projection in equation(2.10) shows that the placement
of the groups corresponds to ameso- (same) or m placement ofa pair of consecutivepseudochiral centers. Thesyndiotactic structure in equation
(2.11) corresponds to a racemic(opposite) or r placement of thecorresponding pair ofpseudochiral centers. It must beemphasized that the m or r
notation refers totheconfiguration of one
pseudochiral center relative toits neighbor.
REPEATI NG UNI T
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REPEATI NG UNI T
I SOMERI SM
MATE 501: Structure and Properties of Polymers-CYL
Optical Isomerism
Geometric Isomerism
Substitutional Isomerism
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-A-B-A-B-A-B-A-B-A-B-A-B-A-
-A-A-A-A-B-B-B-B-B-B-A-A-A-A-
-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B-
A-A-
A-
A-
A-
A-
A-
A-
A-
A-
A-
A-
A-
A-
A-
A-
A-
A-
A-A-
Poly-A-block-poly B
Poly-B-graft-poly A
Alternating copolymers
-A-B-B-B-B-A-A-B-B-A-B-A-A-B-B-
Random copolymers
Homopolymer vs. Copolymer
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MATE 501: Structure and Properties of Polymers-CYL
Six basic modes of linking two or morel id tifi d ( ) A l
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polymers are identified . (a) A polymerblend, constituted by a mixture or mutualsolution of two or more polymers, notchemically bonded together. (b) A graftcopolymer, constituted by a backbone ofpolymer I with covalentlybonded sidechains of polymer II. (c) A blockcopolymer, constituted by linking two
polymersend on end by covalent bonds.(d ) A semi-interpenetrating polymernetwork constituted by anentangledcombination of two polymers, one of whichis cross-linked, that are not bonded toeach other. (e) An interpenetrating
polymer network, abbreviated IPN, is anentangled combinationof two cross-linkedpolymers that are not bonded to eachother. (f ) AB-cross-linkedcopolymer,constituted by having the polymer II
species linked, at both ends, onto polymerI. The ends may be grafted to differentchains or the same chain. The totalproduct is a network composed of twodifferent polymers.
Important Concepts
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Important Concepts
Important Concepts
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Important Concepts
Polymer Architectures
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Polymer Architectures
Contour length, Rmax
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Contour length, Rmax
Polyethylene, witha given MW, what is
the contour length
TransGauche
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Conformations
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Butane CH3-CH2-CH2-CH3potentials
)(mole
kcal
Polyethylene potentials
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Polyethylene potentials
Rotational isomeric state model
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Rotational isomeric state model
Random coil conformation
A number of differentconformations
320,000
Random conformation of al l h i
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macromolecular chain
Random flight
There is not only totally free rotation around the bonds of the chain, but the chainis freely joint (the valency bond angle is no longer fixed but can take any value)
The chain can pass through regions of space that are already occupied by other
bits of itself.
Free Joint Chain:
Three-Dimensional Random Flight
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Three Dimensional Random Flight
i
N
i
lR
1
1/2 Root mean square end-to-end distance
Polymer conformation
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Polymer conformation
A polymer chain can take on an enormous range of
configurations as a result of bond rotations.
These configurations or conformations can be described
statistically, with the end-to-end distance R being a useful
parameter for doing this.
The average value of R taken over all possible conformations
can be expressed in terms of its root mean square value
1/2, which is proportional to the square root of the number of
bonds, N1/2.
The distribution function P(R) takes the form of a Gaussiancurve, to a first approximation.
From Free-Joint to Free Rotate
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o ee Jo t to ee otate
_______
_______
cos1
cos1
cos1
cos1
= Nl2
=l2
2)cos1(
)cos1(cos2
cos1
cos1
N
N
= Nl2
cos1
cos1
Considering restricted (hindered) rotation:
Free rotation:
2
0
2NlCR
Equivalent freely jointed chain
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MATE 501: Structure and Properties of Polymers-CYL
Equivalent freely jointed chain
The equivalent chain has the same mean-square end-to-end distance and the same maximum end-to-end
distance, but has N freely jointed effective bonds of lengthb. b is called Kuhn length
Nb = Rmax = Nb2 =b Rmax =C nl2
N = R2max/ C nl2
b = /Rmax
= C
nl2/R
max
For PE, b = C l2
n/nl cos(/2) = C l/cos(/2)
= C
nl2
Colby and Rubenstein
Chain characteristics of commonpolymers
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polymers
Colby and Rubenstein
Polyethylene potentials
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Polytet rafluoroethylene rotat ional potent ials
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MATE 501: Structure and Properties of Polymers-CYL
Polytet rafluoroethylene rotat ional potent ials
s tableposit ion
gauche (+ )posit ion
gauche( - )posit ion
stableposit ion
~ + 15 ~ -15
Rotation by +15 gives
a right-handed helix
Rotation by 15 yields
a left-handed helix
Helical conformat ions of Class 1Macromolecules
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MATE 501: Structure and Properties of Polymers-CYL
Macromolecules
Polyethylene CH2-
Polytetrafluoroethylene CF2-
21helix
137helix
Wunderlich
Conformat ion helices
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Conformat ion helices
Identify period
c along z
131Perspective drawing and
projection along z
Aut:Rotation necessary to go from lattice pointto lattice point:
Translation necessary to go from lattice point
to lattice point:
u/2 u/c
t: turns to the next identical helix point
u: periodicity (# of helical lattice points
per identical period)
c: distance to the next identical helix
point
Projections
of varioushelices
21 31 41
61525142= 21
62= 31 71 72 73
92918381
32 31
Wunderlich
Secondary Structures of Proteins
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helix pleated sheets
Secondary Structures of Proteins
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The three-fold helix of isotactic polypropylene in front ofthe Giulio Natta Research Center in Ferrara, ItalyPhoto courtesy of Pr. Galli QuickTime?etun
dompresseurGraphiquesontrequis pourvisionner cette image.
Institut Charles Sadron Strasbourg
Helical conformat ions of Class 2
Macromolecules
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Macromolecules
Rotational Potential
Energy
231helix
Polyoxymethylene
Polypropylene (isotactic)
planar zig-zag
view along the planar zig-zag:
d-RH-helix1 120, 2 0
d-LH-helix
1 0, 2 240(-120)
2 95helix102 rotation for each angle from the
shown all-trans conformation
CH2 O
CH2 CH
CH3
Wunderlich
Openness of helices
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MATE 501: Structure and Properties of Polymers-CYL
p
The side group is marked and is takenas the helix lattice point. The morecrowded the backbone chain becomes
due to a large side group close in, the
more does the helix open up. 1and2decrease by about 20 in going from231to 241
Perspective Drawing of
Isotactic Vinyl Polymer Helices
231 272 241
Wunderlich
Dense packing of rods
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MATE 501: Structure and Properties of Polymers-CYL
p g
Packing fraction
Coordination Number CN = 6Compare:
Close pack of sphere CN 12,
K = 0.741;
Packing of rods with CN 4,K = 0.785
907.0 areatotal
circlesofareaK
Wunderlich
Packing of Helices w it hLarge Side groups
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MATE 501: Structure and Properties of Polymers-CYL
Large Side groups
CN = 4
K = 0.785 when touchingK = 0.92 with interpenetrating
helices of 59% thread depthRH screw intermeshing with LH screw
Wunderlich