CH 14 - Polymer Structures

Question 1

What is a polymer?

Answer 1

repeated unit

Question 2

What is a polymer composed of?

Answer 2

hydrocarbons

Question 3

What is a saturated hydrocarbon?

Answer 3

each carbon singly bonded to four other atoms

Question 4

Describe unsaturated hydrocarbons

Answer 4

• double and triple bonds

- can form new bonds

Question 5

Define isomerism

Answer 5

two compounds with same chemical formula can have different structures

Question 6

How is molecular weight determined for polymers?

Answer 6

mass of a mole of chains

Question 7

What is the molecular weight distribution in polymers?

Answer 7

total weight of polymer over total number of molecules

Question 8

What is the degree of polymerization?

Answer 8

average number of repeat units per chain

Question 9

What are the types of molecular structures for polymers?

Answer 9

linear, branched, cross-linked, network

Question 10

Describe the molecular shape of a polymer

Answer 10

• chain bending and twisting possible

- not necessary to break chain bonds to alter molecular shape

Question 11

How is the “radius” of a polymer measured?

Answer 11

chain end-to-end distance

Question 12

Define stereoisomerism

Answer 12

• mirror images

- can’t superimpose without breaking a bond

Question 13

What is tacticity?

Answer 13

stereoregularity or spatial arrangement of R units along chain

Question 14

Define isotactic

Answer 14

all R groups on same side of chain

Question 15

Define syndiotactic

Answer 15

R groups on alternate sides

Question 16

Define atactic

Answer 16

R groups randomly positioned

Question 17

What is a copolymer?

Answer 17

two or more monomers polymerized together

Question 18

What are the types of copolymers?

Answer 18

random, alternating, block, graft

Question 19

Describe a random copolymer

Answer 19

A and B randomly positioned along chain

Question 20

Describe an alternating copolymer

Answer 20

A and B alternate in a polymer chain

Question 21

Describe a block copolymer

Answer 21

large blocks of A units alternate with large blocks of B units

Question 22

Describe a graft copolymer

Answer 22

chains of B units grafted onto A backbone

Question 23

Describe the crystallinity in polymers

Answer 23

• ordered atomic arrangements involving molecular chains
• crystal structures in terms of unit cells
• rarely 100% crystalline

Question 24

What is a spherulite semicrystalline structure?

Answer 24

• alternating chain-folded crystallites and amorphous regions
• structure for relatively rapid growth rates