DACRON DACRON, a polyester We are grateful for wrinkle-free fabrics; -- no starching; no ironing!
KODEL KODEL, another polyester Used to make fabric, tire cord; Mylar film in magnetic recording tape. Aluminized Mylar in Echo satellite, a giant reflector orbiting the earth.
So far, what you have seen are linear polymers; the product of two-point chain growth. Linear polymers are usually “thermoplastic” polymers. They soften with heat, and can be “re-molded” if the product is not perfect.
Three-point chain growth gives rise to cross-linked polymers. These are usually “thermosetting” polymers. They do NOT soften with heat. If the final product is not perfect, it goes into the scrap pile.
1,3-butadienes can undergo 1,4 addition..leaving a double bond for cross-linking.
COPOLYMERS COPOLYMERS consist of polymerizing together two or more different monomers The monomers need not be alternating, but may be combined in various configurations.
Some other interesting polymers: A tough ABS polymer Glyptal resin Polycarbonates Polyurethanes
Three different monomers in an interesting co-polymer. An extremely durable high-impact polymer: NFL helmets, pads, TV & radio chassis, etc.
Glycerol offers THREE points for chain-growth; leading to a cross- linked polymer Glyptal resin makes a strong, solid polymer matrix for electronic parts. It has remarkable strength and rigidity.
A “transesterification” with an ester of a “hypothetical acid”. Many “clear, colorless” soft drink bottles are polycarbonates.
Urethane, another ester of a “hypothetical acid”. Alcohols and phenols react with isocyanates, yielding “urethanes”.
Again, each reactant has 2-point chain growth Volatile materials (Freon 11) added produce bubbles, yielding polyurethane foam. Glycerol can give cross-linking. Bisphenol A gives a different polyurethane.
Phenolformaldehyde Phenol reacts with formaldehyde in dilute base... to give hydroxymethyl groups in the 2 -, the 4- and the 6 – positions...
Further condensation leads to a cross linked polymer... Bakelite known as Bakelite, one of the oldest commercial plastics
2,4,6-triamino-S-triazine undergoes a similar reaction with formaldehyde. The polymer: “Melmac” was the early “cafeteria dishware”.
An interesting research possibility: Then, why not with amines, also...
An interesting “cyclization” reaction:... taken from an early Hiskey & Jung (or Jung & Hiskey) publication in the JACS...
... leading to additional research possibilies... Since pABA cannot “back-bite”, the chain must grow linearly...