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

polymer with high Tg = ____ at mouth temp

polymer with low Tg = ____ at mouth temp

Answer 13

rigid at high Tg

flexible at high Tg

Question 14

effects of cross-linking on properties

Answer 14

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

Question 15

two types of naturally occurring polymers

Answer 15

hydrocolloids, natural rubbers

Question 16

hydrocolloids (2 to know)

Answer 16

agar, alginate

Question 17

types of natural rubber

Answer 17

gutta percha

Question 18

types of hard synthetic polymers

Answer 18

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

Question 19

flexible synthetic polymers

Answer 19

• elastomers

- plasticized methacrylates

Question 20

a polymeric material is made out of polymeric _____

Answer 20

molecules

Question 21

polymeric molecules are composed of ____

Answer 21

monomers

Question 22

acrylic ___ is supplied as a _________ and the final polymer is synthesized in office/lab

Answer 22

resin, liquid monomer

Question 23

acrylic ___ is supplied as a ________ and is ready to be used by the dentist

Answer 23

acid, liquid polymer

Question 24

three steps needed for addition polymerization

Answer 24

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

Question 25

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

Answer 25

activator (energy), initiator (molecule)

Question 26

examples of activators; which is most important in dentistry?

Answer 26

heat, light, chemical; light is most important

Question 27

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

Answer 27

strong, polymerizes

Question 28

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

Answer 28

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

Question 29

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

Answer 29

plasticizers

Question 30

example of a typical plasticizer

Answer 30

water

Question 31

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

Answer 31

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

Question 32

____ can be obtained by combining different monomers with different sequential arrangments

Answer 32

co-polymers

Question 33

viscous material refers to...

Answer 33

- breaking of intermolecular bonds | - disentanglement of molecules

Question 34

example of cross-linked polymer in dentistry

Answer 34

dimethacrylate resins (resin composites)

Question 35

examples of condensation polymerization in dentistry

Answer 35

formation of nylon, polysulfides, silicones

Question 36

examples of free addition polymerization in dentistry

Answer 36

acrylics

Question 37

addition polymerization reaction

Answer 37

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