Supporting material for students registered to subject:

Macromolecular chemistry S112003

Teacher: Jan Merna, Department of Polymers, Institute of Chemical Technology ,Prague

Lecture authored by Jan Merna is licensed under a Creative Commons Attribution-

NonCommercial-NoDerivs 3.0 Unported License

Sources:

Prokopová I.: Makromolekulární chemie, VŠCHT Praha, 2007. (educational text in Czech)

Merna J.: Polymers Instantly, educational text in English, freely accessible from

http://merna.eu/teaching/macromolecular-chemistry/

Encyclopedia of Polymer Science and Technology, J.Wiley Sons, Interscience, Publ., New York, 1964-1991

non-oriented

fringed micelle model

Semi-crystalline polymers:

Amorphous polymers : macromolecules are randomly entangled

Semi crystalline polymers: some degree of regulararrangement of macromolecules

oriented(fiber drawing)

Supramolecular (physical) polymer structure-polymer morphology

Structural requirements for crystalline polymers

•Polymer chain regularity

•Polymer chain flexibility

•Intermolecular interactions

flat lamellae pyramidal lamellae

~ 103 ÅExtended Polymer chain

(from diluted polymer solutions)

Folded chain model

Structure of polymer monocrystal

Spherulite

View in polarization microscope

Dendrit

lamellae branching

Chains orientationin lamellea

Maltesian cross

Irregular crystallite growth from edges/corners

Polymer crystallization from melt or concentrated solutions

Morphology

Chain folding

Shish-kebab(crystallization under stress)

Fringed micellesmodelspherulite

Effect of crystallinity on:

•Mechanical properties (LDPE vs. HDPE): tensile modulustensile strengthHardness

•Thermal properties (PE):Melting temperature

•Optical properties (PS vs. PE): transparency- opacity•(fillers, two amorphous phases - HI PS, foamed PS)

Thermal motions of macromolecules or their segments:

1. Translational motion of entire molecules-flow

2. Motion of macromolecule segment-elasticity

3. Motion of few atoms in main chain or in side groups

4. Equilibrium vibrations of atoms

Glass transition temperature-Tg

glassy-rubbery state

Change of polymer properties (mechanical, refractive index, specific volume)

Determines the application of polymer

Motions 1. and 2. are frozen below Tg

Thermal behaviour of polymers

Amorphous polymerglass transition temperature Tg

flow temperature Tf

Crystalline polymer (hypothetically 100%)melting temperature Tm

Semi-crystalline polymerglass transition temperature flow temperaturemelting temperature

Thermal behavior of polymers- Limit temperatures

Factors influencing Tg

1.Free volume of the polymer: vf

The higher vf the lower Tg

2. Attractive forces between macromolecules

3. Internal mobility of polymer chains - stifness of the chain

4. Molar mass

Determination of Tg

Temperature dependece of thermodynamic property

e.g. specific volume vs. T

Tg change in slope, dv/dT vs. T –discontinuous-second order tdn. transitionTm-discontinuous, first order tdn. transition

Plasticizers

Polymer behavior above Tg

vsp a

Tg TTg´

b

Dependence of specific volume of amorphous polymer on temperature and reaching glass transition temperatureduring fast (a) and slow (b) cooling of polymer sample

Release of macro-Brownian movement in macromolecules

Rubbery state (viscoelastic)

Plastic state, tj. viscous fluid

Flow temper.Tf

Release of movements of macromolecules

Polymer behavior below Tg

„frozen“ segment movement, polymer is in glassy state

Thermal behavior of amorphous polymers

stress

relaxation

Polymer above Tg

Suffcient DP-physical interactions-entenglementsEntropic elasticity

Principle of rubbery elasticity

Thermal behavior of crystalline polymers

a – totally amorphousb – partially crystallinec - hypotetical 100 % crystalline

Tg Tm,b Tm,cT

vsp

abc

Thermodynamics of melting

dGm=dHm-TdSm

Tm=dHm/dSm

Hm ~ intermolecular interactionsdSm~ stiffness of the chain, molar mass

Tg Tm Tf T

E (Pa)

glass

rubber

liquid

109

106

103

Temperature dependence of flexural moduleof partially crystalline polymer

Melting temperatures of selected polymers

> 500

135

308

190

265

CH2 CH

2

CH2

CH2

CCl2

CH(OH) CH2

Polyethylene (HDPE)

syndiotactic

Poly(p-xylylene)

Poly(p-phenylene)

Poly(vinylidenchloride

Poly(vinylcohol)

Tm [°C]

plasticselastomers fibers

polymer dispersionsvarnish/paints

glue

thermoplasticsreactoplastics

thermoplasticelastomers

Clasification of polymers according to properties and applications

Conditions of monomers polymerizability

•Chemical- functionality >2 (fct. groups, multiple bonds, cycles)

•Kinetic-monomer activation: bond polarization+resonance stabilization of product

Rp>Rt (Rtr)

•Thermodynamic aspects

monomer (m) polymer (p)kp

kdp

Thermodynamic aspects

Pn* + M Pn+1*

kp

kdp

K=1/[Me]

dGmp=-RT lnK

Termination + transfer neglected

dGmp=dHmp-TdSmp

Tc=dHmp/dSmpCeiling temperature

No depolymerization of terminated chains

dSmp= -100 to -120 JK-1mol-1

Independent on monomer structure

dHmp:

•Differences in resonance stabilization of monomer and polymer

•Difference in steric tension in monomer and polymer

•Difference in non-bonding interaction in monomer and polymer

Monomer -Hmp (kJ/mol)

ethylene............................................... 101,5

vinylchloride....................................... 111,5

vinylacetate........................................... 89,5

propylene............................................... 85,9

methylacrylate....................................... 84,5

acrylonitrile.......................................... 77,5

vinylidenechloride................................. 75,5

butadiene............................................... 73,0

styrene.................................................... 70,0

methylmethacrylate.............................. 57,5

izobutylene............................................. 53,0

-methylstyrene.................................... 34,5

Polymerization enthalpy at 25°C

∆Gmp < 0

Gmp = Hmp - TSmp

Ceiling temperature of polymn Tc – above no polymer formation

Gmp = Hmp - TcSmp = 0

Rate of polymn. = rate of depolymerization

!!!! All, chemical, kinetic and thermodynamic;conditions must be fulfilled !!!!

Monomers suitable for chain polyreactions:

- multiple bond between C atoms in molecule

- multiple bond between C and heteroatom in molecule

- (hetero)cyclic molecules

C C C CC C. . + -

radical polymerization ionic

A BA B+ -

Cationic polymerization

Anionic polymerization

+

-CH2 CH

D

+

-

CH2 CH

A

B

CH2CH2

+-O

CH2H O+

O-

Hmp Smp Gmp

1. < 0 < 0 < 0 at T < Tc

2. < 0 > 0 < 0 always not known

3. > 0 < 0 > 0 always

4. > 0 > 0 < 0 above Tf

Thermodynamical conditions of polymerizability

Monomer-H

(kJ mol-1)

-S

(J K-1 mol-1)

Ethene 93 155

Propene 84 116

But-1-ene 83,5 113

2-Methylpropene 48 121

Buta-1,3-diene 73 89

Isoprene 75 101

Styrene 73 104

-Methylstyrene 35 110

Vinylchloride 72 -

Vinylidenchloride 73 89

Tetrafluoroethene 163 112

Acrylic acid 67 -

Akrylonitrile 76,5 109

Maleinanhydride 59 -

Vinyl-acetate 88 110

Methyl-acrylate 78 -

Methyl-methacrylate 56 117

Enthalpy and entropy of polymn. for selected monomers at 25 °C *

* Brandrup J., Immergut E.H.

(Eds), Polymer Handbook, Wiley-

Interscience, New York 1989.

Sawada H., Thermodynamics of

Polymerization, Marcel Dekker

1976

Phase state

Monomer Polymer index for molar

termodynam. quantity

gas condensed (amorph.) gc

gas condensed (crystal.) gc´

Liquid condensed (amorph.) lc

Liquid condensed (crystal.) lc´

Liquid solution of polymer in monomer ls

solution m. solution of polymer ss

solution m. condensed sc

Means of polymerization

Monomer Tc (°C)

Styrene 310

Methylmethakrylate 220

α-Methylstyrene 61

Ceiling temperature Tc of selected monomers

dTc

Tc

dp

dT=

ΔH

TΔV=

ΔV

ΔHmp

dp

ln(Tc)p = ln(Tc)101,3 kPa + ΔV

ΔHmp

p

Dependence of Tc on pressure

Bond Energy between atoms capable of chain formation

Bond kJ/mol Bond kJ/mol

C – C

B – B

S – S

P – P

Se – Se

Te – Te

Si – Si

Sn – Sn

Sb – Sb

Bi – Bi

Ge - Ge

347,8

289,1

264,0

222,1

209,5

205,3

186,6

197,0

176,0

167,6

164,2

C – B

C – O

C – N

C – Al

C – S

C – Si

Al – O

B – O

Si – O

B – N

P - O

372,9

331,0

305,9

258,1

257,6

241,3

578,2

475,6

444,1

437,0

342,3

Capability to form isochain

PeriodeGroup

III. IV. V. VI.

2 ~5 B C N O

3 Al 45 Si 4 P 30 000 S

4Sc Ti Cr

Ga 6 Ge 5 As ? Se

5Y Zr Nb Mo

In 5 Sn 3 Sb ? Te

6La Hf Ta W

Tl Pb ? Bi Po