Experiment 10: Polymers

History The first synthetic polymers was Bakelite, a phenol-formaldehyde polymer. Bakelite was commercially introduced in It was developed as a synthetic substitute for shellac. Used at first to make billiard balls but later used for molded insulation, valve parts, knobs, etc. Rayon, the first synthetic fiber Precursors of Rayon – 1884 – developed as artificial silk from collodion Marketed in 1891 but was short-lived – Viscoid – 1892, a cellulose polymer – Rayon – 1926, regenerated cellulose

Polymers Definition – A polymer is a molecule with a very high molecular weight which is composed of repeating simple structural units called monomers. Often referred to as macromolecules. – Homopolymer – single recurring monomer – Heteropolymer or Copolymer – at least 2 different monomer subunits

Polymers There are natural polymers and synthetic polymers. Natural polymers – DNA, proteins, starches Synthetic polymers – – Polyurethanes, Styrofoam

Methods of Production Two major methods depending on the nature of the subunits… 1. Chain-reaction polymers (aka addition polymers) Monomers are attached to each other by a chain-reaction. The reaction may have either a radical, an anion, or a cation as an intermediate. -Polypropene from propene, used in luggage and carpeting -Polystyrene formed from styrene, used in packaging -Polymethyl methacrylate formed from methyl methacrylate, also known as Lucite or Plexiglass 2.Step-Growth Polymerization (aka condensation polymers) Monomers have functional groups at both ends. When these ends react, the result is the polymer w/the loss of a small molecule such as water or HCl. - Usually natural polymers are formed in this way - Monomer units can be different

Homopolymers vs. Copolymers Homopolymer – polymer comprised of a single type of monomer unit Copolymer (also called a heteropolymer) – contains two ore more distinct momomers

Chain-reaction polymers Polystyrene is a simple polymer made from repeating units of styrene. (R. is an initiator) Note : Most stable intermediate will always be benzyl. The dimer shown would continue the same steps growing by one styrene each time.

Formation of “Slime” Tautomers of vinyl alcohol PVA is not made from vinyl alcohol because aldehyde tautomer favored. It is made from Polyvinyl acetate with saponification to the alcohol. + H 2 O

Step-growth polymerization – Release of water + 4 H 2 O

Recycling Codes

TODAY The properties of 3 polymers will be investigated. 1.SOLUBILITY OF POLYSTYRENE

2.HOW MUCH WATER CAN IT HOLD? absorption/super-absorb-powder.html absorption/super-absorb-powder.html 3.CROSS-LINKED POLYMER “SLIME”

Waste Put your waste from each experiment into the corresponding waste container…. – Experiment “A” goes into “A” waste container – Experiment “B” goes into “B” waste container – Experiment “C” goes into “C” waste container You may keep your SLIME! … just don’t eat it.