MSE 2001: 4.2 Amorphous Solids - Polymers

Monomers

A chain of repeat molecular units

High Molecular Weight

This type of molecular weight results in:
Greater elastic modulus
Greater toughness
Greater strength
Higher service temperature
Greater tensile strength

Homopolymer

A type of polymer structure that has the same repeating units

Copolymer

A type of polymer structure that has different repeating units

hang off

Side groups (aka pendant groups) on a polymer ____ ___ of the polymer backbone

Side group variations

• rigidity, bulky like styrene

• polar side groups, e.g. PVC (stronger van der waals + hydrogen bonding between chains, higher Tm)

• length

• longer, flexible side groups, decrease Tg

All of these are examples of…

Polymer properties

• less dense, harder to pack, higher melting point, higher Tg, harder for chains to slide past each other

• flexibility

• density

• strength

• service temperature

These are examples of what affected by side group variations?

Atactic

A type of tacticity in which side groups are

• randomly arranged

• have less dense packing

• are harder to crystallize

Isotactic

A type of tacticity in which side groups are

• same-side arranged

• are easier to crystallize

Syndiotactic

A type of tacticity in which side groups are

• every-other arranged

• are easier to crystallize

Linear

What type of polymer structure is this?

Comb

What type of polymer structure is this?

Star

What type of polymer structure is this?

Grafted

What type of polymer structure is this?

Ring

What type of polymer structure is this?

Randomly branched

What type of polymer structure is this?

Network

What type of polymer structure is this?

Blend

What type of polymer structure is this?

Blend

This type of polymer structure architecture is a physical mixture of two or more polymers

covalent

Chemical cross links involve ______ bonds between two polymer chains

Physical cross links involve ____ bonds between two polymer chains

increases

Increasing cross-linking (increases, decreases) strength and rigidity

Cross-linking methods

• Catalysts (e.., vulcanization or photocuring)

• network formers (monomers which can make 3+ bonds)

These are examples of…

Homopolymer

What type of polymer is this?

Block copolymer

What type of polymer is this?

Statistical copolymer

What type of polymer is this?

ABC triblock terpolymer

What type of polymer is this?

Number average molecular weight

What equation does this represent?

Weight average molecular weight

What equation does this represent?

Atactic

What is the tacticity of this polymer?

Isotactic

What is the tacticity of this polymer?

Syndiotactic

What is the tacticity of this polymer?