Macromolecular Chemistrywillson.cm.utexas.edu/Teaching/Chem367L392N/Files/Lecture 3.pdf · Paul J...

Chemistry 367L/392NPaul J Flory 1910Paul J Flory 1910--19851985

The Nobel Prize in Chemistry 1974

"for his fundamental achievements, both theoretical and experimental, in the physical chemistry of macromolecules"

Macromolecular ChemistryMacromolecular Chemistry

Chemistry 367L/392N

Polymer MorphologyPolymer Morphology

Crystalline and semi crystalline Amorphous

Chemistry 367L/392N

Polyethylene CrystalsPolyethylene Crystals

Chemistry 367L/392N

XX--ray scatteringray scattering

Chemistry 367L/392N

MorphologyMorphology� Amorphous polymers are referred to as glassy

polymers– they lack crystalline domains that scatter light and are

transparent….Poly(methyl methacrylate)– they are weaker polymers and generally more flexibility– on heating, amorphous polymers are transformed from

a hard glass to a soft, flexible, rubbery state

� Glass transition temperature, Tg: the temperature at which a polymer undergoes a transition from a hard glass to a rubbery solid (ca. 100 degrees for polystyrene)

Chemistry 367L/392N

Discovery of TeflonDiscovery of Teflon

� Dr. Roy J. Plunkett– DuPont Employee

– Working on Refrigerants

– “Empty Tank” Curiosity

� Tetrafluoroethylene– Carbon based molecule

– A simple “mer” molecule

Fluorine

Carbon

Chemistry 367L/392N

Differential Scanning CalorimeterDifferential Scanning Calorimeter

Chemistry 367L/392N

Differential Scanning CalorimetryDifferential Scanning Calorimetry

Chemistry 367L/392N

Heating a glassHeating a glass

Chemistry 367L/392N

Changing Rubber into Glass!!Changing Rubber into Glass!!

Chemistry 367L/392N

DSC DataDSC Data

Chemistry 367L/392N

The ability to bend without breaking

Chemistry 367L/392N

NotationNotation� Show the structure by placing parenthesis

around the repeat unit or common structural unit “CRU”

� n = average degree of polymerization (DP)

CH CH2 n

Chemistry 367L/392N

NotationNotation� Degree of polymerization

CH CH2 n

M = n M0 where M = polymer molecular weight, M0= Molar mass of CRU

Chemistry 367L/392N

NomenclatureNomenclature

� Let’s face it, this is a bit of a mess!!

Chemistry 367L/392N

Nomenclature MethodsNomenclature Methods� Source name (more common use)

– based on monomer name (polystyrene)

� IUPAC, constitutional repeating unit– used in both source and structure

names…messy!

� Abbreviations and acronyms– PMMA [poly(methyl methacrylate)]…also

common

� Trade names– marketing and technological literature

Chemistry 367L/392N

Structure Based (Structure Based (homopolymershomopolymers))

� IUPAC nomenclature– common repeating group (CRU) is named as a

bivalent organic group according to IUPAC

� Identify, orient, and name the CRU– based on seniority and direction

1. heterocyclic rings (ring size over # of hetero)

2. Heteroatom (O, S, N, P, Si)

3. carbocycles (unsaturated over saturated)

4. carbon chains

Chemistry 367L/392N

3. Fundamental PrinciplesThis nomenclature method rests upon the selection of a preferred CRU of which the polymer molecule is a multiple. Wherever possible, the CRU and subunits are named according to the IUPAC-recommended nomenclature of organic chemistryIn this nomenclature, the steps to be followed when naming a polymer are:

Name the polymer.4.

Name the preferred CRU by citing, from left to right, the names of the subunits, including their substituents, if present.

3.

Select the preferred CRU.2.

Write the structure of the polymer chain. A sufficient portion of the chain should be written to show structure repetition. The portion that repeats is a CRU.

1.

IUPACIUPAC

Chemistry 367L/392N

IUPACIUPAC

� Finding the CRU

or

2-substitution1-substitution

highest seniority is an oxygen atom

poly[oxy(1-bromoethylene)].

http://www.chem.qmul.ac.uk/iupac/rssop

Chemistry 367L/392N

Choose the direction so that the locants of the substituents are as low as possible.

4

Choose the direction so that the locants of free valences of the subunit are as low as possible;

3

Identify the single subunit and its substituents;2

write the structure of a representative portion of the polymer chain1

IUPAC Choosing CRU IUPAC Choosing CRU

poly [(Z)-but-1-ene-1,4-diyl](double bond takes lowest locant;

poly(1-phenylethylene)

Chemistry 367L/392N

Source Based (Source Based (homopolymershomopolymers))� Use name of actual monomer

– polymonomer, i.e. polyethylene

– common names may be used for monomer

� Use ( ) when two words or substituents– poly(vinyl chloride), poly(1,2-difluoroethylene)

H2C CH

styrene

H2C C

CH3

CH3

isobutylene

H2C CH

C CH2

CH3

isoprene

H2C CH

C N

acrylonitrile

Chemistry 367L/392N

Source Based (copolymers)Source Based (copolymers)� Architecture terms

– -co- (unspecified arrangement), poly(A-co-B)

– -alt- (alternating)

– -block- Polyacrylonitrile-block-polybutadiene

Chemistry 367L/392N

ExamplesExamplesCH CH2

O C CH3

O

CH CH CH2 CH2

CH CH2

C N

CH2

OO

O

CH2

Ph

1. Poly(1-acetoxyethylene) - structure2. Poly(vinyl acetate) - source

1. Poly(but-1-ene-1,4-diyl)2. Polybutadienea

1. Poly(1-cyanoethylene)2. Polyacrylonitrile

1. Poly(methylene)2. Polyethene; polyethylene

1. Poly[(2,5-dioxotetrahydrofuran-3,4-diyl)(1-phenylethylene)]

2. Poly(maleic anhydride-alt-styrene)

Chemistry 367L/392N

Industrial Influence: Trade Names Industrial Influence: Trade Names

� PVC poly (vinylidene chloride) Saran wrap� PVC poly (vinyl chloride) Pipe and records� PET poly (ethylene teraphthalate) Coke bottles, Dacron � Polystyrene Cups and packaging� Delrin Bushings and engineering parts� Lexan Bullet proof glass� Teflon Non stick pans� PVDF speakers and microphones� Kevlar bullet proof vests� Nylon Rope and fiber