Condensation Polymers- polyesters and polyamides

Condensation Polymers Involves 2 monomers that have different functional groups. They also involve the elimination of water or another small molecule. Hence the term condensation polymer. Monomer A + Monomer B  Polymer + small molecule (normally water). Common condensation polymers include polyesters (the ester linkage) and polyamides (the amide linkage as in proteins).

Polyesters An example is terylene, a polymer of benzene-1,4- dicarboxylic acid and ethane-1,2-diol. The ester linkage is formed between the monomers

Polyesters You need to be able to reproduce the formation of terylene, and possibly predict the structures of other polyesters

Polyamides These involve the linkage of two monomers through the amide linkage as in proteins (e.g. silk)

Nylon 6,6 a polyamide Nylon 6,6

Kevlar a polyamide

Uses of polyamides The main use of polyesters and polyamides is as fibres in clothing. Most clothing now has a degree of manufactured fibres woven into the natural material (such as cotton). This gives the material more desirable characteristics, such as stretchiness, and better washability. Don’t forget that proteins are also polyamides, you must know how the linkage works with natural polymers such as proteins.

Recycling of Plastic PETE =polyethylene terephthalate V =polyvinyl chloride LDPE= low density polyethylene HDPE= high density polyethylene  PP=polypropylene PS =polystyrene OTHER= polyesters, acrylics polyamides, teflon etc.  Most communities recycle #1 and #2 but some communities have found buyers for the other recycled plastics and thus recycle more kinds (Los Angeles recycles all 7 types) Very few communities recycle #6 and #7

Recycling of Plastic Recycling symbol was never patented…thus recycling symbol used on EVERY type of plsatic including non-recyclable plastics Much less recycling occurs than you think like Only around 27% of plastic bottles are recycled. Americans use 2.5 million plastic bottles every hour! Most of them are thrown away! 13.3% of plastic packaging was recycled in 2008 50% of plastic is used ONLY ONCE and thrown away Estimate is 5% of all plastic is recycled We generate enough plastic waste EVERY YEAR to circle the earth 4 times More than 1 milliion plastic bags are used EVERY MINUTE on Earth

The Law of Unintended Consequences plastic have resulted in serious environmental pollution as used items are casually discarded. Charles Moore, an American oceanographer, in 1997 discovered an enormous stew of trash, estimated at nearly 100 million tons, floating in the Pacific Ocean between San Francisco and Hawaii. Named the "Great Pacific Garbage Patch", this stew of trash is composed largely (80%) of bits and pieces of plastic that outweigh the plankton 6 : 1, in a region over twice the size of Texas. It is a serious environmental and health problem. Persistent objects such as six-pack rings and discarded nets trap sea animals. Smaller plastic scraps are mistaken for food by sea birds.

"Great Pacific Garbage Patch" 5% is recycled (photo Indonesia) By 2050, oceans will have more plastic than fish

Biodegradable Polymers Plastics derived from natural materials, such as cellulose, starch and hydroxycarboxylic acids are more easily decomposed when exposed to oxygen, water, soil organisms and sunlight than are most petroleum based polymers. The two natural polyesters that are finding increasing use as replacements for petroleum based plastics are polylactide (PLA) and polyhydroxyalkanoates (PHA). PLA materials (derived from milk) are currently used in a number of medical applications, such as sutures, stents and dialysis media PHA (polyhydroxyalkanoates) are synthesized by microorganisms such as Alcaligenes eutrophus, grown in a suitable medium and fed appropriate nutrients Biodegradable polymers cost tens to hundreds of times more than regular plastic (at this time…research and support needed)