BASIC TYPES OF POLYMERIZATIONS

Question 1

a process by which monomer units are attached one at a time in chainlike fashion to form a linear molecule. The composition of the resultant product molecule is an exact multiple of that of the original reactant monomer.

Answer 1

Chain-growth / addition polymerization

Question 2

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

Answer 2

unsaturated

Question 3

In chain-growth polymerization, there are a ____ number of these active sites.

Answer 3

limited

Question 4

The growing polymer in chain-growth polymerization is a ____, and polymerization proceeds via chain mechanism.

Answer 4

free radical

Question 5

Is a method of polymerization by which a polymer forms by the successive addition of free-radical building blocks (repeat units).

Answer 5

Free-radical polymerization (FRP)

Question 6

Step in polymerization which involves the acquisition of an active site by the monomer.

Answer 6

Initiation

Question 7

initiation of free-radical polymerization is brought about by the addition of small quantities of compounds called ____.

Answer 7

initiators

Question 8

Initiation in a free-radical polymerization consists of two steps

Answer 8

Dissociation of initiator
Association of single monomer

Question 9

Step in polymerization which involves the linear growth of the polymer chain by the sequential addition of monomer units to this active growing chain molecule.

Answer 9

Propagation

Question 10

at some point, this occurs due to annihilation of the radical center of the propagating chain

Answer 10

Termination

Question 11

Termatiom process where two propagating chains are terminated when two radicals combine to form an electron-pair (covalent) bond as in the reaction above.

Answer 11

Combination / Coupling

Question 12

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

Answer 12

Disproportionation

Question 13

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 13

Disproportionation

Question 14

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

Answer 14

Chain transfer

Question 15

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

Answer 15

Ionic polymerization

Question 16

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

Answer 16

Cationic polymerization

Question 17

Cationic polymerization employs a true ______ that is restored at the end of the polymerization and does not become incorporated into the terminated polymer chain.

Answer 17

catalyst

Question 18

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

Answer 18

Anionic polymerization

Question 19

The strength of the base required to initiate polymerization _____ with increasing electronegativity of the substituent on the monomer.

Answer 19

decreases

Question 20

commonly used initiator systems for anionic polymerization

Answer 20

Alkali metal and alkali complexes
Organometallic comppunds
Lewis base
High energy radiation

Question 21

Cationic polymerizations proceed at ____ rates at ____ temperatures.

Answer 21

high; low

Question 22

Propagation in anionic addition polymerization results in the complete consumption of ____.

Answer 22

monomer

Question 23

In polymerizations of this type, each monomer is inserted between the growing macromolecule and the initiator.

Answer 23

Coordination polymerization

Question 24

The field of coordination polymerization originated in the mid-1950s with the pioneering works of ______ in Germany and ______ in Italy.

Answer 24

Karl Ziegler; Giulio Natta

Question 25

the most prominent Ziegler-Natta catalyst in the present

Answer 25

stereoregular (isotactic) polypropylene

Question 26

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

Answer 26

Step-growth polymerization

Question 27

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

Answer 27

reactive or functional groups

Question 28

In step-growth polymerization, there is usually a _____ by- product such as water that is eliminated (or condensed).

Answer 28

low-molecular-weight

Question 29

form a large class of commercially important polymers. It is also used as film (mylar) and in bottle applications.

Answer 29

Polyester

Question 30

Are a special class of polyesters derived from carbonic acid. second largest by volume engineering thermoplastics next to polyamides.

Answer 30

Polycarbonate

Question 31

Also called nylons, as they are commonly called, are characterized by the presence of amide linkages on the polymer main chain.

Answer 31

Polyamide

Question 32

Are condensation polymers obtained from the reaction of dianhydrides with diamines.

Answer 32

Polyimides

Question 33

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

Answer 33

Polybenzimidazoles and Polybenzoxazoles

Question 34

Also known as ladder polymers or linker polymers, are a type of polymer that consists of repeating units connected by aromatic linkers, such as benzene rings.

Answer 34

Aromatic ladder polymer

Question 35

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

Answer 35

Formaldehyde

Question 36

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

Answer 36

Polyether

Question 37

Also known as aromatic polythioethers

Answer 37

Polysulfide

Question 38

May be synthesized by the nucleophilic substitution of alkali salts of biphenates with activated aromatic dihalides

Answer 38

Polysulfone

Question 39

A form of chain-growth polymerization in which the terminus of a polymer chain attacks cyclic monomers to form a longer polymer.

Answer 39

Ring-opening polymerization