MatSE 202 Introduction to Organic Materials Science or Introduction to Polymer Materials? Outline: topics to be covered 1. Introduction to organic or soft materials. 2. The building blocks a review. 3. Synthesis of organic materials synthetic polymers. 4. Synthetic polymer architecture. 5. Conformations, structure and morphology. 6. Natural polymers. 7. Mixing: Solutions and Blends 8. Mechanical and rheological properties. 9. Processing/Composites
Outline Today s Class Why on earth should I bother to learn anything at all about polymers?
POLYMER SCIENCE AND ENGINEERING WHAT IS IT? THE SCIENCE OF LARGE MOLECULES I am inclined to think that the development of polymerization is, perhaps, the biggest thing that chemistry has done, where it has the biggest effect on everyday life LORD TODD President of the Royal Society of London SYNTHESIS POLYMER PHYSICS AND PHYSICAL CHEMISTRY CHARACTERIZATION ENGINEERING
What Are Polymers And Why Are They Important? Long Chain Molecules Extraordinary Range Of Physical Properties Many (Not All) Are Cheap They Are Just Damn Interesting!!!!!
First things first - what is a polymer? Polymers are very large molecules (macromolecules) that are comprised or built up of smaller units or monomers. Poly...mer many units M M M M M M or (M) n
How big are Polymers?
Molecular Weight Check out the chain of beads on the right. Imagine each bead is an ethylene unit Ethylene Polyethylene C H = C H 2 2 [- C H - C H -] 2 2 n Then, because there are only 200 ethylene units in this chain (i.e. it is a 200 - mer), its molecular weight is only 5,600 (= 28 x 200).Commercial samples have molecular weights much larger than this!
A last (for now!) comment on molecular weight
Some Basic Definitions POLYMER MONOMERS A large molecule made up of small building blocks The building blocks HOMOPOLYMER COPOLYMER BLEND What you get if the building blocks are all the same A polymer made up of different monomers A mixture of different polymers
Applications Packaging/films (plastics!) Everyday household stuff (more plastics!) Paint Adhesives Structural materials Auto's,aerospace,etc. Fibres (Fibers) Electronic applications Elastomers
Plastics Cheap and Nasty? "In the five decades since the end of World War II, plastic has crept increasingly, and often invisibly, into our homes, cars, offices, even our bodies. Some of us have plastic hearts, joints, valves, limbs... Don t get hosed this time! Plastic has become the defining medium of our Synthetic Century precisely because it combines the ultimate twentieth century characteristics artificiality, disposability and synthesis all rolled into one. The ultimate triumph of plastic has been the victory of package over product, of style over substance, of surface over essence."
The Spectacular Growth of Synthetic Polymers
Are Natural Materials Better?
Are synthetic materials naturally inferior? (Bad pun intended!) You can get it from your morning juice or out of a bottle. It can be made (expensively!) from Rose hips, or synthesized (cheaply!) chemically. Either way, it s still ascorbic acid.
Do traditional materials get a break? An English milk cart hauling milk in glass bottles. Your instructor remembers milk being delivered this way when he was a kid! But glass can end up like this!
Do traditional materials get a break? Is PVC inherently evil, or does it play a useful role in health and medicine?
Polymers and the Environment
Only in America! Wasteful Excess?
Wasting Energy? Crude Oil Usage 100 90 80 70 60 % 50 40 30 20 10 0 Fuel Plastics Petrochemicals
How much was spoiled or went bad before it could be sold? Wasting Energy?
Polymers and the Environment You can do four things with garbage: you can bury it, you can burn it, you can recycle it or you can send it on a Caribbean cruise Ed Koch (NY mayor emeritus). Approximate Composition of European Household Waste Cans Plastics Glass So, shouldn t we be a bit more worried about paper? Other Waste Kitchen Scraps (Food) Paper & Board 0 10 20 30 40 Percent
Polymers and the Environment What are we going to do with all this stuff? Some polymers are now biodegradable
Biodegradable Polymers Biodegradable corn pens.
Composting A compostable plastic bag. Courtesy: Proterra.
Let s just burn the stuff! Calorific Values of Common Wastes 50 45 40 35 Kj/g 30 25 20 But we don t mean like this! 15 10 5 There s quite a bit of energy in these materials. 0 Food Waste Municipal Waste Newspapers PVC Coal Oil Polyethylene Polypropylene Polystyrene
Why not Recycle? First you ve got to sort it!
Why not Recycle?
So, why do we use polymers?
Weight
Weight
Toughness and Transparency
Toughness and Transparency
Glues and Sealants
Glues and Sealants
Flammability
Flexibility
Rubber Elasticity
Processability Easy processability (automated & fast) is what makes plastic products cheap. Just consider the price (e.g. per lb) of plastics vs. wood, metal, glass, or ceramics?
From packaging materials, through fibers, foams and surface coatings, to continuous extrusions and large scale moldings, plastics have transformed almost every aspect of life. Without them much of modern medicine would be impossible and the consumer electronics and computer industries would disappear. Plastic sewage and water pipes alone have made an immeasurable contribution to public health worldwide. No Need to Apologize!