Polymer Science Quiz 1

poly

many

meres

parts

The covalent bond is the ___

predominant bond in polymers

Saturated Hydrocarbons are

C-C single bonds. ex: ethane C2H6

Unsaturated hydrocarbons

have carbon to carbon double or triple bonds

isomerization

same chemical formula can have different structures (C8H18)

What is the abbreviation for Polyethylene

PE

What is the abbreviation for Polyvinyl chloride

PVC

What is the abbreviation for Polystyrene

PS

What is the abbreviation for Polypropylene

PP

What is the Monomer form of PE

CH2=CH2

Repeat Unit of PE

-[CH2CH2]-

Monomer form of PVC

CH2=CHCl

Repeat Unit of PVC

-[CH2CHCl]-

Monomer form of Polystyrene (PS)

Repeat unit of PS

Repeat unit of PP

Monomer form of PP

CH2=CH-CH3

If the distance “r” between the polymer and solvent is greater what does that interaction mean?

the solvent and polymer interact well (chain is relatively extended).

If the distance between the polymer and solvent is small what does that mean?

poor interaction, polymer chain is contracted (balled up)

Low molecular weight

not many repeat units in the polymer chain

What is the lowest a PDI can be and what does that mean?

Lowest it can be is 1 meaning all polymer chains the same length (same number of repeat units)

DP

degree of polymerization = number of repeat units in the chain

what is the behavior of a thermoplastic

can heat it up and it flows. It is a physical change (PS, PE, PP). ex: ice → water

what is a thermoset’s behavior

heat it up and it sets (forms solid). It is a chemical change and after the solid is formed and heated it again it burns and gives off a smell. cannot remelt a thermoset. ex: epoxy and urethane

what is this arrangement?

isotactic = all R groups are on the same side of the plane formed by the chain backbone. the solid black is the top plane.

What is this arrangement?

syndiotactic= opposite side; R groups lie on opposite side of the plane formed by the chain backbone.

What iso and syndiotactic polymers have in common?

they have “order” so they are partially crystalline. order means they stack well

What is this polymer arrangement ?

Atactic= R groups have no preferred placement, so random meaning they are amorphous ( no order)

What does Conformation mean in terms of tacticity?

Arrangements arising from rotation about single bonds (twisting). For long, flexible chains the total number is nearly infinite.

Do you need to break bonds to create Conformations?

NO, chain bending and twisting is possible by rotation of carbon atoms around their chain bond.

What does a configuration describe?

The stereochemical arrangement of atoms = cannot change without breaking chemical bonds, so must break chemical bonds

What is an amorphous polymer structure?

individual polymer chains randomly coiled/intertwined with no molecular order or structure.

Amorphous polymers only have ___

Tg

What is Tg?

glass transition temperature, below Tg long range cooperative motions of individual chains can not occur (stuck in place). Above Tg polymer chains can move.

What is a characteristic of an amorphous polymer below Tg?

hard, stiff, brittle, and transparent

What is a crystalline polymer?

polymer chains with very regular structures that can be arranged in highly regular structures.

Crystalline polymers have __ and _

Tg and Tm

Tm

crystalline melting temperature

crystalline polymers are typically….

strong, tough, and more resistant to solvents, and not transparent

What arrangement is this depicting?

amorphous

What two arrangements occur in real life ?

amorphous and semicrystalline.

What arrangement is this depicting?

semicrystalline

Polymers are rarely __ crystalline unless made in __ in lab environments, which means slow and carefully controlled growth rates

100 %, small quantities

Semi-crysalline polymers have _ and _ regions in the same polymer

amorphous and crystalline

What is the Addition or chain growth polymerization mechanism?

it means the sequential addition of monomers aka chain reaction polymerization.

What happens during an addition reaction ?

A free radical with an unpaired electron reacts to open a C=C double bond of a monomer and then adds to it with an electron remaining unpaired. It keeps growing until two free radicals react with each other to end the polymer chain growth. think “R.”

What is a condensation reaction?

reaction of 2 molecules, often the reaction also produces water or hcl. Aka step growth or step reaction polymerization.

Examples of condensation reactions

A+B → A-B + h20