Basic Types Of Polymerization

Question 1

A process through which a large number of monomer molecules react together to form a polymer.

Answer 1

Polymerization

Question 2

IUPAC Definition: A chain reaction in which the growth of a polymer chain proceeds exclusively by reactions between monomer and reactive site on the polymer chain with regeneration of the reactive sites at the end of each growth step.

Answer 2

Chain-growth Polymerization or Addition Polymerization

Question 3

Chain-growth polymerization involves the addition of ____________ molecules to a rapidly growing chain.

Answer 3

Unsaturated

Question 4

Enumeration.
Three fundamental steps of Chain-growth Polymerization.

Answer 4

1. Initiation
2. Propagation
3. Termination

Question 5

Enumeration:
Classification of Chain-growth Polymerization.

Answer 5

1. Free radical Polymerization
2. Cationic Polymerization
3. Anionic Polymerization
4. Coordination or Stereoregular Polymerization

Question 6

IUPAC Definition: A chain polymerization in which the kinetic-chain carriers are free radicals.

Answer 6

Free Radical Polymerization

Question 7

Most frequently, initiation of free radical polymerization is brought about by the addition of small quantities of compounds called __________.

Answer 7

Initiators

Question 8

Usually a weak organic compound that can be decomposed thermally or by irradiation to produce free radicals, which are molecules containing atoms with unpaired electrons.

Answer 8

Initiators

Question 9

Enumeration.
Initiation in a free-radical polymerization consists of two-steps.

Answer 9

1. Dissociation
2. Addition

Question 10

It involves the dissociation of a radical initiator molecule which is easily dissociated by heat or light into two free radicals.

Answer 10

Chain Initiation.

Question 11

Involves the linear growth of the polymer chain by the sequential addition of monomer units to this active growing chain molecule.

Answer 11

Propagation

Question 12

IUPAC Definition: A reaction of an active center on the growing polymer molecule, which adds one monomer molecule to form a new polymer molecule one repeat unit longer.

Answer 12

Chain Propagation

Question 13

The sequence of propagation reactions is terminated at some point due to annihilation of the radical center of the propagating chain.

Answer 13

Termination

Question 14

Enumeration.
Two termination step that involves the reaction of any two free radicals with each other.

Answer 14

1. Combination
2. Disproportionation

Question 15

Two propagating chains are terminated when two radicals combine to form an electron-pair (covalent) bond

Answer 15

Combination (Coupling)

Question 16

The reaction of the unpaired electrons of two chains to form a covalent bond between them.

Answer 16

Combination

Question 17

This termination step involves two growing molecules that react to from two “dead chains”.

Answer 17

Disproportionation

Question 18

The transfer of a hydrogen atom from one chain to the other so that the two product chain molecules are unchanged in length but are no longer free radicals.

Answer 18

Disproportionation

Question 19

A growing polymer chain is deactivated or terminated by transferring its growth activity to a previously inactive species.

Answer 19

Chain Transfer

Question 20

Involve chain carriers or reactive centers that are organic ions or charged organic groups.

Answer 20

Ionic Polymerization

Question 21

IUPAC Definition: An ionic polymerization in which the kinetic-chain carriers are cations.

Answer 21

Cationic Polymerization

Question 22

A type of chain growth polymerization in which a cationic initiator transfers charge to a monomer, which then becomes reactive.

Answer 22

Cationic Polymerization

Question 23

The catalysts generally require the presence of a Lewis base such as water, alcohol, or acetic acid

Answer 23

Cocatalyst

Question 24

IUPAC Definition: An ionic polymerization in which the kinetic-chain carriers are anion.

Answer 24

Anionic Polymerization

Question 25

A form of chain-growth polymerization or addition polymerization that involves polymerization of monomers initiated with anions.

Answer 25

Anionic Polymerization

Question 26

Enumeration. Commonly used initiator systems for anionic polymerization.

Answer 26

1. Alkali Metals and Alkali Metal Complexes 2. Organometallic Compounds 3. Lewis Bases 4. High-energy Radiation

Question 27

Initiate polymerization by transfer of an electron to the double bond of the monomer.

Answer 27

Alkali Metals and Alkali Metal Complexes

Question 28

Initiation by _________ and __________ occurs by a direct attack of these compounds on the double bond of the monomer molecule.

Answer 28

Organometallic Compounds, Lewis Bases

Question 29

Complexing of the monomer to the initiator frequently precedes the insertion process and this polymerization is therefore often called _______________.

Answer 29

Coordination Polymerization

Question 30

The range of type of this catalysts was subsequently extended to produce polymers exhibiting a wide range of stereoregular structures including those derived from dienes and cycloalkenes.

Answer 30

Ziegler-Natta Catalysts

Question 31

It refers to a type of polymerization mechanism which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers.

Answer 31

Step-growth Polymerization

Question 32

It refers to the molecule’s interlinking capacity or the number of sites it has available for bonding with other molecules under the specific polymerization conditions.

Answer 32

Functionality

Question 33

In step-growth polymerization, the stepwise reaction occurs between pairs of chemically ____________ on the reacting molecules.

Answer 33

Reactive or Functional Groups

Question 34

Enumeration. Categories of Step-growth Polymerization.

Answer 34

1. Polycondensation 2. Polyaddition

Question 35

Small molecule is eliminated at each step.

Answer 35

Polycondensation

Question 36

Monomers react without the elimination of a small molecule.

Answer 36

Polyaddition

Question 37

It is used as film (mylar) and in bottle applications.

Answer 37

Polyester

Question 38

Special class of polyesters derived from carbonic acid.

Answer 38

Polycarbonates

Question 39

Characterized by the presence of amide linkages (-CONH-) on the polymer main chain.

Answer 39

Polyamides

Question 40

Condensation polymers obtained from the reaction of dianhydrides with diamines.

Answer 40

Polyimides

Question 41

Families of synthetic heterocycles with a wide range of applications due to their physical and chemical properties.

Answer 41

Polybenzimidazoles and Polybenzoxazoles

Question 42

A type of polymer that consists of repeating units connected by aromatic linkers, such as benzene rings.

Answer 42

Aromatic Ladder Polymers, Ladder Polymers or Linker Polymers

Question 43

Employed in the production of aminoplasts and phenoplasts, which are two different but related classes of thermoset polymers.

Answer 43

Formaldehyde Resins

Question 44

Polymers consisting of monomers joined together by ether linkages (two carbon atoms bonded to an oxygen atom).

Answer 44

Polyethers

Question 45

Closely related to polyethers in structure and properties and is typically used as electrical insulators and structural parts in the building of engines and vehicles.

Answer 45

Polysulfides

Question 46

Another family of linear aromatic polymers that are tough, high temperature-resistant engineering thermoplastics.

Answer 46

Polysulfones

Question 47

True or False. 1. In step-growth, monomers bearing functional groups such as -OH, -COOH, -NH2, -NCO, etc. undergo step polymerization. 2. In chain-growth, monomers with carbon-carbon unsaturation undergo polymerization when an active center is formed.

Answer 47

Both statements are true.

Question 48

True or False. 1. In step-growth, the growth of polymer molecules proceeds by a stepwise intermolecular reaction, normally with the elimination of small molecules as by-products of condensation. The molecule never stops growing during polymerization. 2. In chain-growth, each polymer molecule/chain increases in size at a rapid rate once it growth has been started by formation of an active center. When the macromolecules stop growing, it can generally not react with more monomers.

Answer 48

Both statements are true.

Question 49

True or False. 1. In step-growth, any two molecular species present can react. 2. In chain-growth, only growth reaction adds repeating unit two at a time of the chain.

Answer 49

Statement 1 is true. Statement 2 is false. “Two” -> “One”

Question 50

True or False. 1. Step-growth: Monomer units can react with each other or with polymers of any size. Growth occurs in a series of fits and starts as the reactive species of a monomer or polymer encounters other species with which it can form a link. 2. Chain-growth: Growth of a polymer molecule is caused by a kinetic chain of reactions involving rapid addition of monomer to an active center that may be a free radical, ion, or polymer-catalyst bond.

Answer 50

Both statements are true.

Question 51

True or False. 1. Step-growth: This can occur even in the absence of an added catalyst. 2. Chain-growth: The active center is produced by some external source (energy, highly reactive compound, or catalyst)

Answer 51

Both statements are true.

Question 52

True or False. 1. Step-growth: The average size increases with conversion. 2. Chain-growth: Consists of growing chains of intermediate sizes.

Answer 52

Both statements are true.

Question 53

True or False. 1. Step-growth: Backbone polymer chains contains heteroatoms such as N, O, S, etc. at a regular intervals due to condensed interunit links. 2. Chain-growth: Usually the backbone of polymer chains consists of -C-C- linkages and other kinds of atoms such as O, N, S, etc. may appear in the side groups.

Answer 53

Both statements are true.

Question 54

IUPAC Definition: A polymerization in which a cyclic monomer yields a monomeric unit which is acyclic or contains fewer cycles than the monomer.

Answer 54

Ring-opening Polymerization

Question 55

A form of chain-growth polymerization in which the terminus of a polymer chain attacks cyclic monomers to form a longer polymer. The reactive center can be radical, anionic, or cationic.

Answer 55

Ring-opening Polymerization