10.2 NOTES Petrochemicals and Polymers

Chemists use molecule knowledge to design new molecules The hydrocarbons not used for energy, lubricants, and road tar can be called builder molecules

C.1 Creating New Petrochemicals Until the early 1800s all objects used by humans were made from wood, stone, or metals or other things that came from living organisms (wool, silk)   Monomers are simple molecules that are the building blocks of many materials

Polymers Very large molecules composed of 500 to 20,000 repeating monomers   Can be both naturally occurring or synthetic Natural polymers Celluloid – comes from wood Shellac – type of varnish that comes from animals Synthetic polymers Man made Nylon, polyester, plastics

Many materials common today were unknown before the mid-1900s Petrochemicals Compounds produced from oil or natural gas   Direct uses include: detergents, pesticides, pharmaceuticals Indirect uses include: raw materials for paint, fabrics, insulation, foam, moldings

There are very few builder molecules, but they are very versatile Ethene Molecular formula - C2H4   Structural formula Sometimes called ethylene Has a double covalent bond 4 valence electrons are shared between two atoms

Addition reaction A reaction that takes place at a double or triple bond site in organic molecules   Another two atoms or groups are added to the carbons in the double and triple bond Example reaction:

Addition polymer Polymer formed through addition reaction   Example:

Many different combinations with ethene molecules   Vinyl chloride- adding Cl Acrylonitrile- adding cyanide (CN)

Styrene- adding benzene ring   Molecule properties are very different based on the functional group added

C.2 Polymer structure and properties Unmodified, the arrangements of covalent bonds in long string-like polymer molecules causes the molecules to coil loosely A collection of polymer molecules (such as those in a sample of molten polymer) can intertwine, much like strands of cooked spaghetti In this form, the polymer is flexible and soft   Use a pencil line on paper to represent a liner polymer, draw a collection of loosely coiled polymer molecules.

Ductiliy – the ability to be drawn into strands Ductility depends on temperature Warm: polymers slide past each other, more flexible Cold: More rigid Flexibility can also be changed by adding molecules that act as an internal lubricants Polyvinyl chloride (PVC) is used in rigid pipes and house siding With added lubricant molecules, polyvinyl chloride becomes flexible enough for use in such consumer goods as raincoats and inflatable pool toys.

Branched polymers Polymers with side chains perpendicular to the original chain   Draw at least two different models of branched-chain polymers. Try to vary your representations – the forms of branched polymers can differ greatly. Branching changes the properties of a polymer by affecting the ability of chains to slide past one another and by altering intermolecular forces.

Draw several linear polymer chains that have been cross-linked. Cross-linking The process of increasing polymer strength and firmness as connecting 2 polymer chains together Draw several linear polymer chains that have been cross-linked.  

Draw several cross-linked, branched polymers Draw several cross-linked, branched polymers. Then describe how cross-linked branched polymers compare to cross-linked linear polymers.    NEXT PAGE!  Cross linked branched polymers will be stronger than cross-linked linear polymers because there will be more connections. Polymer strength and toughness is controlled by arranging the polymer chains so that they are arranged so that they lie in the same general direction

Draw several aligned linear polymer chains.  

Draw several aligned and cross-linked linear polymer chains.