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Soft condensed matterMaterials which are easily deformable by external stresses, electric or magnetic fields, or even by thermal fluctuations; typically possess structures which are much larger than atomic or molecular scales; the structure and dynamics at the mesoscopic scales determine macroscopic physical properties . http://www.seas.harvard.edu/weitzlab/

PolymersColloidsAmphiphiles (surfactants, lipid)Liquid crystalsMolecular crystalsBiological matter

Soft condensed matter(Soft amtter)

2Examination08:00-12:00Friday 12/12

VAProblem class P2613:00-15:00Thursday 4/12

FZSummaryP3010:00-12:00Tuesday 2/12

FZApplication of electronic polymersP2608:00-10:00Monday 1/12

VA and FZLab2IFM13:00-15:00Thursday 27/11

OIElectronic polymersP3410:00-12:00Tuesday 25/11

OIElectronic polymersP2208:00-10:00Monday 24/11

VA and FZLab1IFM13:00-15:00Thursday 20/11

NSBiopolymersP3010:00-12:00Tuesday 18/11

NSSoft MatterP2608:00-10:00Monday 17/11

NSSoft Matter P3013:00-15:00Thursday 13/11

FZCrystalline polymersP3010:00-12:00Tuesday 11/11

VAProblem classP1808:00-10:00Monday 10/11

FZmolten stateP3013:00-15:00Thursday 6/11

FZGlassy amorphous stateP3010:00-12:00Tuesday 4/11

FZPolymer solutionP2608:00-10:00Monday 3/11

FZThe rubber elastic stateP2613:00-15:00Thursday 30/10

FZChain conformationP3010:00-12:00Tuesday 28/10

FZTerminology and statisticsP188:00-10:00Monday 27/10

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Insulating polymers

Conductive polymers and others mostly base on research articles.

Bokakademin in Kårallen, Campus Valla.

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Chapter 1 Introduction to polymer physics

Polymers

Biopolymers (natural polymers)

Synthetic polymers

Biopolymers are produced by living system, for instance, silk, wool, more?

Synthetic polymers

produced by the chemical industry, plastics, rubbers, fibers (big scale, 106 ton/year)

synthesized by researchers in labs (small scale, mg)

5

Polymer semiconductors

n

Polyacetylene

S nPolythiophene

nPoly (para-phenylene-vinylene)

n

Polyfluorene

Some conjugated (semi-conducting) polymers

Characterized by typical

-electrical

-optical properties

They are versatile.

6

Why polymers are so useful?

• The properties of polymers are very diverse and can be modified to meet the special requirements of applications

http://www.konarka.com/http://www.polymervision.com/

http://www.planete-energies.com/content/features/plastics/applications.html

http://www.thinfilm.se/index.php?option=com_content&task=blogcategory&id=0&Itemid=59

2

7

Anisotropic mechanical property (Young’smodulus)

8

Electrical property

An introduction to polymer physics, David I Bower

O O

S

OO

S

O O

S

OO

S

O O

S

OO

S

S OOO

S OOO

S OOOH

++

_ _

PEDOT-PSS

poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonate) (Baytron PH500 )

Y-H. Zhou, F. Zhang, et al., App. Phys. Lett., 92, 233308 (2008).

9

Optical properties and structures of polymers

400 600 800 1000 1200 14000 .0

0 .2

0 .4

0 .6

0 .8

1 .0

1 .2

1 .4

1 .6

AM

1.5

(Glo

bal t

ilt,

wm

-2nm

-1)

W ave leng th (nm )

S S

NS

N

n

δδδδ-δδδδ+

δδδδ+

S S

NSN

NN

O

O

O

O

n

SS

S

N N

n

OO

APFO3 (Alternating polyfluorenes) APFO-Green5

LBPP1(Low bandgappoly phenylene)

F. Zhang, et al, APL 84(19), (2004), 3906.F. Zhang, et al, Adv. Mater. 18, 2169 (2006).

E. Perzon, et al, Adv. Mater. 19, 3308(2007).10

The variety of polymer materials

Physical state:

• Liquid: polymer melts and solutions (very viscous)

• Crystalline: polymer can crystallize, but usuallycrystallisation is not complete, semi-crystalline.

• Liquid crystalline: Some polymers can line up to form liquid crystalline materials.

• Glasses: amorphous solid.polymer glasses are verycommon, polystyrene, poly(methyl methacrylate)

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• Physics: Explain phenomenon, behavior and find correlationamong variables and rules.

• Polymer physics:Describe the properties of polymers and explain the correlation between microstructure and macroproperties.

microstructure macro propertiesdetermine

How?To modify property

Applications need special properties Design molecular structures12

1.1 Fundamental definitionPolymer (Macromolecule):

A substance composed of molecules by the multiple repetition of one or morespecies of atoms or group of atoms (constitutional repeating units ) linked eachother in amounts sufficient to provide a set of properties that do not varymarkedly with the addition of one or a few of the constitutional repeating unts. (Swedish chemist Jöns Jacob Berzelius invented in 1832 )

Polyethylene

n=103~106

polypropylene

n

Poly (para-phenylenevinylene)

3

13

Oligomer: A molecule with only a few constitutinal repeating units.

Physical properties vary with n, mp (93-95°C, 211-214°C, 290°C, 280°C )

2,2',5',2''-Terthiophene (3T)2,2',5',2'',5'',2'-Quaterthiophene (4T)

a-Sexithiophene (6T)a,w-Dihexylsexithiophene (DH-6T)

http://www.sigmaaldrich.com/Area_of_Interest/Chemistry/Materials_Science/Energy_Source_Materials/Conducting_Polymers/Conductive_Thiophene_Oligomers.html

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Mono mer:is the substance that the polymer is made

from.

poly propylenepropylene

Polymerization

Repeating unit

Monomer PolymerPolymerization

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BondsPrimary bond (covalent bond)

Secondary bond

Bond stability Physical properties(Modulus)

RT ~2.5kJ/mol (300K), 4kJ/mol at 500K

Bond energy

Bonds in polymers

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Covalent bonds

Ethane (C2H6)

Ethylene (Ethene)(C2H4)Two elements share an electron pair, form bond

Link the atoms of the polymerchains , which are very strong with dissociation energy 300-500 kJ/mol

σ and π bond

Difference between σ and π bond ?

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Secondary bondsThe interaction between atoms of different molecules

(important for the properties of polymers)Van der Waals bond ~10kJ/molDipole-dipole bond >10kJ/molHydrogen bond 10 ~50kJ/mol

u=ql dipole moment

Induced dipole moment

Dispersion forces (London forces)

acts between all atoms and molecules

Hydrogen bond

Dipole-dipole bond

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1.2 Configuration (”Permanent” stereostructure of a polymer )

Polymerization method determines configurationIf a polymer has more than one type of chemical group attached to eachmain chain carbon atom, then different arrangments of the groups in threedimensions are possible.

Isotactic( similar side groupsappear on the same side of the chain)

Syndiotactic( on alternate sides )

Atactic (random arrangement of the groups).

C2H2XY

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Polymers with double bonds

Stereoforms of 1,4-polybutadiene showing only the constitutional repeating unit with the rigid central double bond

Double bond is rigid and allows no torsion , and the cis and trans forms are not transferable into each other.

1,4-polybutadiene

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microstructure macro properties

determine

How?

Atactic (irregular configuration)Isotactic (regular configuration)

AmorphousCrystalline

Totally depends on configuration (local geometry)

The entire structure of a polymer is generated during polymerization

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1.3 Homopolymer and copolymerHomopolymer consists only one type of monomer (A):

A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-

Copolymer consists 2 or more monomers (A, B,…): (why do we needcopolymers? )Block copolymer, Graft copolymer, Alternating copolymer, Random copolymer

Organize monomer 22

1.4 Molecular Architecture (organize chains)

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Structure properties

Linear polymer, atoms more or less arranged in a long chain(backbond)(102-103), if small chain (few atoms) attached (pendant group)

A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-

B B B

Branched polymer if B getting longer, comparable to the length of the backbone chain.

Profound effects on rheologicalproperties, chain mobility

linear or branced polymer soften or melt when heated, so that they can be moulded and remoulded by heating (Thermoplastics) . 24

Crosslinked polymer

Star polymer

Used as additives in motor oilhttp://www.diva-portal.org/kth/theses/abstract.xsql?dbid=4808

Sometimes there is no backbond at all. A polymer is built in such a way that branches keep growing out of branchesand more branches grow out of thosebranches. (Dendrimers )

heavily crosslinked polymers are normally rigid, can not melt on heating and they decompose if T is high enough (Thermosets) .

lightly crosslinked polymers are reversiblystretchable to high extensions (Rubber or elastomers)

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1.5 Conformation:A conformational state refers to the stereostructure of a

molecule defined by its sequence of bonds and torsion angles .

Example of conformational states of C7H16. The right-hand form is generated from the left-hand form by 120°torsion about the σ bond indicated by the arrow.

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The polymer characteristics, such as microstructure, architecture, degree of polymerization (n), chemicalcomposition of heteropolymer (copolymer) are all fixedduring polymerization and can not be changed withoutbreaking covalent bonds.

However, a single flexible macromolecule can adopt manydifferent conformations . Conformation is the spatial structure of a polymer determined by the relative locations of its monomers.

Conformation depends on Flexibility of the chainInteraction between monomers on the chainInteraction with surroundings

AttractiveRepulsiveRelative strength ofT

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How the interaction influence the conformation ?Consider a chain with n=1010 bonds, l ≈ 10-10m, contour length L=nl=1010×1010 ≈ 1mMagnify all lengths by 108, that is l ≈ 1cm

1. strong attraction between monomers, the conformation of the polymer is a denseobject called collapsed globule, V ≈ nl3 ≈ 104m3, R=3√V≈20 m, a classroom

2. No interaction between monomers, Random walk, R ≈n1/2l ≈ 103 m, a campus3. With excluded volume repulsions, R ≈ n3/5 l ≈10 km, a city4. With long-range repulsions, R ≈ nl ≈ 105 km, the order of the distance to the

Moon.

The multitude of conformations available for polymers is veryimportant for their properties

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• Cofiguration? How to change• Conformation? How to change• Why flexibility increase with T• Why rubber rapid response to external

force

More on conformation in Next Chapter

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1.5 Commen polymers

Most polyethylene applications are in the areas of film, molding, cable and pipe

http://www.ciba.com/index/ind-index/ind-pla/ind-pla-polymersandpolymerprocessing/ind-pla-pol-polyethylene.htm

Properties: Flexible at low temperature, colorless, non-toxic transparent. High density PE(HDPE) is hard, tough and resilient. Most of HDPE is used in manusfacture of containers. Low density PE(LDPE) is soft and has a rather lowwater vapor permeability, but high oxyg°en and aroma p ermeability and is sensitive to fats and oils. Tm ~ 137 °C, Tg -130 to - 80 °C

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The textile application is one of the largest polypropylene markets in size, being above 1700 kT in 2004 in Western Europe. Dishwasher, safe food containers, indoor and ourdoor carpets (easy to make colored PP and doesn’t absorb water).

http://www.totalpetrochemicals.biz/content/documents/143_b2_5_polypropylene_for_fibre_applications.pdf

Properties: PP has a high degree of crystallinity(isotactic) or high amorphous(atactic). The Tm, mechanical properties and transparencyare related to the crystallization, is a good insulator. PP is resistant to attack by polar chemicals, such as, soap, alcohols and its water absorption is very low, it reserves double duty as a plastic and as a fiber. Tm ~ 180 °C, Tg ~ -17 °C.

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PVC is useful plastic because it resists to fire and water. It is used to make raincoats and shower curtains and water pipe . PVC is commonly used in the construction sector, for example in window frames and shutters , pipe cabling and coating , etc. High amorphous ~11% crystallinity, Tg ~84 °C

PS is a inexpensive and hard plastic insulator, used in toys, the housingsof things like hairdryers, computers and kitchen appliancesTm ~270 °C, Tg ~100 °C

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PMMA is a clear colorless polymer, used extensively for optical application. It is an amorphous thermoplastic, that is, hard and stiff. PMMA has a good stability against UV radiation, but it has poor chemical resistance.

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1.6 Statistical molar mass (the mass of one mole)

MonodisperseThe sample is monodisperse if all polymers in a given sample

have the same number of monomers.

M=nMmon

Where n is the number of monomers in a polymer molecule, is the degree of polymerization, Mmon molar mass of monomer,

M the molar mass of a polymer

The molar mass distribution ranges over three to four orders of magnitude for many polymers

PolydisperseThe sample is made up of individualmolecues that have a distribution of degree of polymerization (depends on synthetic method)

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Molar mass dependence of the equilibriummelting point of oligo- and polyethylene.

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Average molar mass

The most commonly used averages are defined as follows. The number -average is given by:

where Ni is the number of molecules of molar mass Mi, and ni is the number fraction of those molecules.

The weight -average is given by:

where Wi is the mass of the molecules of molar mass Mi, and wi is the mass fraction of those molecules.

ii

i

ii

iii

n Mn

N

MNM ∑

∑

∑==

∑∑

∑

∑

∑===

iii

iii

iii

ii

iii

w MwMN

MN

W

MWM

2

36

The z-average is given by:

The viscosity-average is given by:

where a is the exponent in the Mark-Houwink equation. It takes values between 0.5 and 0.8 depending on the combination of polymer and solvent.

∑

∑==

iii

iii

z

MN

MNM

2

3

a

iii

i

aii

v

MN

MNM

1

1

=

∑

∑ +

7

37

A polymer sample consists of a mixture of threemondisperse polymers with molar masses 250000, 300000 and 350000g/mol in the ratio of 1:2:1 by numberof chains, calculate Mn, Mw and Mw/Mn.

Solution:Let the total number of chains with molar mass

250000g/mol be N, thenMn=(N×250000+2N×300000+N×350000)/(N+2N+N)=300000g/mol

Mw=…………………=304200g/mol

Mw>MnMw/Mn=1.014 (polydispersity index)

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The correlation of Mn, Mw, Mz and Mν

Mn≤Mv ≤Mw ≤Mz

All these averages are equal only for a perfectly monodispersepolymer.

In all other cases, the averages are different:M n <M v <M w <M z . The viscosity average is often relatively closeto the weight average.

Standard deviation ( σ) and Polydispersity index

The breadth of the molar mass distribution, measuring how widelyspread the values i a data set. If the data points are close to the mean, then σ is small.

1−=n

w

n

n

M

M

M

σ

n

w

M

M

39

Experimental techniques for molar mass determinatio n

40

1.7 Thermal transitions and physical structures

The logarithm of the relaxation modulus (10 s) as a function of temperature for semicrystalline (isotactic) polystyrene and fully amorphous (atactic) polystyrene in three "versions": low molar mass uncrosslinked, and high molar mass uncrosslinked and crosslinked.