chem 86 - polymers (properties of polymers)

Unsaturated

Molecules with double and triple bonds are called __

Alkenes

Molecules with double bonds are called __

Alkynes

Molecules with triple bonds are called __

polymer

a molecular compound with a high molar mass and composed of repeating units called monomers.

macromolecules

large molecules with distinct physical properties compared to small molecules.

Naturally occurring polymers

proteins, nucleic acids, cellulose, and rubber.

Polysaccharides

polymer of cellulose

Polyisoprene

polymer of rubber

poly(hexamethylene adipamide)

polymer of nylon

poly(ethylene terephthalate)

polymer of Dacron

poly(methyl methacrylate)

Lucite or Plexiglas

Rubber

originally thought to consist of small molecular units, but later discovered to be an enormously large molecule composed of thousands of atoms held together by covalent bonds.

Hermann Staudinger

the scientist who showed that rubber and similar materials are composed of large molecules.

structural isomers

different arrangements of atoms in a molecule with the same chemical formula.

geometric isomers

molecules with the same connectivity of atoms but different spatial arrangements.

monomers

simple repeating units that make up polymers.

Synthetic Polymer

polymers created by combining monomers through addition reactions and condensation reactions.

Addition reactions

reactions involving unsaturated compounds with double or triple bonds, such as CPC and CqC, leading to the addition of other atoms or groups to the molecule.

Hydrogenation

a type of addition reaction in which hydrogen is added to an unsaturated compound.

Polyethylene

a stable polymer used in frozen food packaging wraps, produced by joining ethylene monomers through an addition-reaction mechanism (has crystalline properties).

Initiator molecule (R2)

a substance that, when heated, generates two radicals to initiate the polymerization process.

Tyvek

a specially treated polyethylene, is used for home insulation.

Homopolymer

a polymer composed of only one type of monomer.

Teflon

a homopolymer synthesized by the radical mechanism.

Polytetrafluoroethylene

teflon

Poly(vinyl chloride) (PVC)

a homopolymer synthesized using the radical mechanism.

Linear chain polymers

Repeated units joined end to end in single chains, having high density and tensile strength (e.g. polyethylene, PVC, nylon, polyester).

Isotactic

a polymer in which the R groups are all on the same side of the asymmetric carbon atoms.

Syndiotactic

a polymer in which the R groups alternate to the left and right of the asymmetric carbons.

Atactic

R groups disposed at random (leading to poor packing, rubbery texture, amorphy, and low strength)

Geometric isomers

different spatial arrangements of atoms in molecules.

Isotactic isomer

__ has the highest melting point, greatest crystallinity, and superior mechanical properties among the different structural arrangements of polypropenes.

Branched Polymers

polymers where Side-branch chains are connected to the main chains, reducing chain packing efficiency (e.g. Polypropylene, amylopectin and glycogen)

Crossed linked polymers

polymers where adjacent linear chains are joined to one another at various positions by covalent bonds. Tougher, less flexible, high melting points

Vulcanized Rubber

heated natural rubber w/ sulfur for harder, stronger and elastic traits

Natural Polymer

Polymers that occur in nature (e.g. natural rubber, natural silk, cellulose, starch, proteins)

Biopolymers

natural polymers are also known as __

Latex

Natural rubber is obtained as __ from rubber trees

isoprene

The monomer of natural rubber

Hevea brasiliensis

Tree which rubber (poly-cis-isoprene) is extracted from

11000 to 20000

There may be as many as __ isoprene units in a polymer chain of natural rubber

External force

if strong enough, can cause individual polymer chains to slide past one another, resulting in a loss of rubber's elasticity.

Charles Goodyear

in 1839, he discovered the process of vulcanization, which involved cross-linking natural rubber with sulfur (catalyzed by zinc oxide). Vulcanization prevents chain slippage and made rubber more durable and elastic.

Vulcanization

the process of cross-linking rubber to improve its elasticity and durability, enabling various practical and commercial uses like automobile tires and dentures.

Synthetic rubbers

(aka elastomers) often derived from petroleum products such as ethylene, propene, and butadiene.

Polychloroprene (neoprene)

a synthetic rubber formed by the polymerization of chloroprene molecules, known for its comparable or superior properties to natural rubber.

Synthetic Polymer

Polymers synthesized in the lab (e.g. Nylon, polyethene, polystyrene, synthetic rubber, PVC, Teflon)

Styrene butadiene rubber (SBR)

a synthetic rubber produced by the addition of butadiene to styrene in a 3:1 ratio. It is referred to as a copolymer because it contains two different monomers.

Copolymer

a polymer composed of two or more different monomers.

Polymer condensation process

involves the reaction between hexamethylenediamine and adipic acid to produce nylon 66. Nylon 66 is so named because it contains six carbon atoms in both hexamethylenediamine and adipic acid.

Nylon 66

first synthesized by Wallace Carothers at Du Pont in 1931.