(Concept) POLYMERS

Question 1

Macromolecule built up by the repetition of small chemical units joined by covalent bonds

Answer 1

Polymers

Question 2

Bonds present in polymers

Answer 2

Covalent

Question 3

Other name for repeat unit

Answer 3

“Mer”

Question 4

The sequential reactions of monomers/oligomers to form a polymer chain

Answer 4

Polymerization

Question 5

What are the polymerization mechanisms?

Answer 5

1. Chain-reaction (Addition) | 2. Step-growth (Condensation) | 3. Ring-Opening

Question 6

Where does sequential addition of monomer units occurs?

Answer 6

At an active center

Question 7

How does an active center form?

Answer 7

Through a reaction between an initiator (or catalyst) species and the monomer unit

Question 8

Steps in chain-reaction (Addition)

Answer 8

Initiation, propagation, and termination

Question 9

An active site is also a/an…

Answer 9

Unpaired electron (or a free radical din (?))

Question 10

How does step-growth (condensation) occur?

Answer 10

Through a series of step-wise reactions in which any 2 molecules (monomers, dimers, trimers, etc.) may react at any time.

Question 11

Where does step-growth (condensation) happen?

Answer 11

Between chemically reactive groups

Question 12

Are there any eliminations in step-growth (condensation) reactions?

Answer 12

Yes, usually a small molecule
is eliminated.

Question 13

What is ring-opening polymerization mechanism?

Answer 13

The breaking of cyclic molecules and their subsequent formation of a linear polymer

Question 14

Chain-reaction (addition) may be differentiated through…

Answer 14

Presence of double bonds/alkenes monomers

Question 15

Consists of only one repeating unit

Answer 15

Homopolymer

Question 16

Has more than one repeating unit

Answer 16

Copolymer

Question 17

Arrangements possible in copolymer structures

Answer 17

Random, alternating, block, or graft

Question 18

Refers to the atomic composition and chemical structure of the monomer

Answer 18

Primary Structure

Question 19

Refers to the size and shape of a single polymer molecule

Answer 19

Secondary Structure

Question 20

Refers to the intermolecular bonding forces and structural order of the polymer

Answer 20

Tertiary Structure

Question 21

Refers to the number of bonds that a given monomer can form

Answer 21

Functionality

Question 22

Refers to monomers with an interlinking capacity of 2.

Answer 22

Difunctional Monomers

Question 23

Refers to monomers with an interlinking capacity greater than 2.

Answer 23

Polyfunctional Monomers

Question 24

This indicates the number of repeating units strung together

Answer 24

Degree of Polymerization

Question 25

Is there an increase or decrease for the following: (1) mechanical properties, (2) melting temperature, and (3) mechanical strength, (4) viscosity, when there is a higher DP?

Answer 25

Increase in DP results in: increase in (1) mechanical properties, (2) melting temperature, and (3) mechanical strength, (4) viscosity

Question 26

What is conformation?

Answer 26

Arrangement due to the rotation about single bonds

Question 27

Types of sequence isomerism / positional isomerism (?)

Answer 27

1) Head to tail, 2) Head to Head, 3) Tail to tail

Question 28

Types of stereoisomerism (w respect to spatial arrangment)

Answer 28

Isotactic, syndiotactic, atactic

Question 29

Types of structural isomerism (or geometrical isomerism?)

Answer 29

Cis, trans

Question 30

Refers to those with repeat units having a double bond between chain carbon atoms

Answer 30

Geometrical isomers

Question 31

Types of molecular structure

Answer 31

Linear, branched, cross-linked, network

Question 32

Factors for crystallinity

Answer 32

Rate of cooling, molecular chemistry, and chain configuration

Question 33

Many bulk polymers that are crystalized from a melt are semicrystalline and form a [---] structure.

Answer 33

Spherulite

Question 34

A spherulite structure is formed when....

Answer 34

Bulk polymers that are crystalized from a melt ends up semicrystalline

Question 35

Faster rate of cooling (inc/dec.) chance for crystallinity

Answer 35

Decrease

Question 36

Irregularity in structure (inc/dec.) chance for crystallinity

Answer 36

Decrease

Question 37

It can be said that cis forms are (rubbery/crystalline) while trans are (rubbery/crystalline).

Answer 37

Cirs - rubbery ; trans - crystalline

Question 38

(Less/more) flexible chains are more susceptible to thermal agitation.

Answer 38

More flexible chains

Question 39

A material that can increase the distance between adjacent polymer chains making it easier for them to move about.

Answer 39

Plasticizers

Question 40

Polarity (inc./dec.) bonding between chains

Answer 40

Increases

Question 41

Morphology of crystalline polymers depend on 3 factors...

Answer 41

Solvent medium, Temperature, Cooling Rate

Question 42

Conformations of polymers (or polyethylene crystals)

Answer 42

Planar zigzag, helical, orthorombic, triclinic, monoclinic

Question 43

If there is steric hindrance, the preferred conformations of polymers is...

Answer 43

Helical