Week 2: Polymers

Question 1

Any of numerous natural and synthetic compounds of usually high molecular weight consisting of up to millions of repeated linked units, each a relatively light and simple molecule

Answer 1

polymer

Question 2

smallest repeating molecule in polymer chain

Answer 2

monomer

Question 3

reaction of monomers to synthesize/form

polymers

Answer 3

polymerization

Question 4

elimination/release of a smaller molecule while forming covalent bonding between monomers (e.g., water, ethanol, etc)

Answer 4

condensation polymerization

Question 5

polymerization in which free radicals (unpaired electron) form to react with vinyl compounds to form the polymer.

Answer 5

addition polymerization

Question 6

hard rigid glass polymer

Answer 6

acrylic resin

Question 7

forms an adhesive water-soluble polymer

Answer 7

acrylic acid

Question 8

polymer aspects

Answer 8

• length
• temp
• alignment
• disentanglement

Question 9

the number of repeating units in a polymer, the number of monomer units joined together

Answer 9

degree of polymerization

Question 10

degree of polymerization multiplied by the molecular weight of the repeating units; “average mass of molecules”

Answer 10

molecular weight

Question 11

the _____ the molecular weight, the ____ the strength and the rigidity because it is more difficult to _____/____

Answer 11

higher, higher, uncoil/disentangle

Question 12

3 physical states of polymers

Answer 12

elastomers
hard amorphous polymers
hard semicrystalline

Question 13

effects of cross-linking on properties

Answer 13

• more purely elastic, less viscous
• may have higher Tg
• hard and more brittle

Question 14

types of hard synthetic polymers

Answer 14

• condensation polymers
• free radical addition polymers (mostly linear)
• free radicals addition polymers (cross-linked)

Question 15

flexible synthetic polymers

Answer 15

• elastomers

- plasticized methacrylates

Question 16

a polymeric material is made out of polymeric _____

Answer 16

molecules

Question 17

polymeric molecules are composed of ____

Answer 17

monomers

Question 18

three steps needed for addition polymerization

Answer 18

• generation of radicals
• propagation of reaction
• termination of reaction

Question 19

generation of radicals is accomplished when ______/(____) works on the ______(___) of reaction

Answer 19

activator (energy), initiator (molecule)

Question 20

examples of activators; which is most important in dentistry?

Answer 20

heat, light, chemical; light is most important

Question 21

intramolecular forces in polymeric molecules are ___ because covalent bonds are formed while polymer ____

Answer 21

strong, polymerizes

Question 22

intermolecular forces between polymeric molecules to form a polymeric material can be _________ due to…

Answer 22

less to more strong; entanglement/friction, van der Waals forces, covalent bonds

Question 23

small molecules that act reducing friction between polymeric molecules and thus soften the polymer to make it more flexible/visoelastic

Answer 23

plasticizers

Question 24

example of a typical plasticizer

Answer 24

water

Question 25

cross-linker polymers are usually more ____________ because mobility of molecules is limited

Answer 25

more rigid/harder/stronger, less viscoelastic (more purely elastic)

Question 26

viscous material refers to…

Answer 26

• breaking of intermolecular bonds

- disentanglement of molecules

Question 27

addition polymerization reaction

Answer 27

1. generation of free radicals
2. propagation of reaction
3. termination of propagation