Chem 1100 Lecture 20Outline of Last Lecture I. Hybrid CarII. PhotovoltaicIII. EconomicsIV. Solar ThermalOutline of Current Lecture I. Plastics & PolymersII. Common PlasticsIII. PolymerizationIV. HDPE vs LDPEV. Addition PolymersVI. Intermolecular ForcesCurrent LectureI. Plastics & Polymersa. Polymer: is made up of many different units and there are many different kinds.i. Natural Polymers: Silk, Cotton, DNA, Proteinsii. Man Made (synthetic): Polyester & Nylonb. Monomer: one unit and multiple monomers make up a polymeri. The building blocks of polymersc. Plasticsi. All plastics are polymers but not all polymers are plastics.ii. Plastics are used for a wide variety of materials (clothing, rubber, packaging, construction, sports, insulators)iii. Useful for their ability to be molded into different shapesiv. Synthesized from available starting materialsv. DNA and cellulose are polymers that are NOT plastics.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.d. Polymer Characteristicsi. Molecular weight is based on the length of the chainii. Chain arrangement: depends on how tightly they are packed and how they are organizediii. Chain Branching: determines how close the individual chains can come togetheriv. Monomer Orientationv. Monomer Identity: different groups of atoms on these molecules that determines the molecules chemical propertiesvi. Inter-chain bonds (cross-linking): if you don’t have the right type of monomers in your sequence cross linking won’t be possible because not all bonds interactII. Common Plasticsa. The Big 6i. 60,000 types of plastics are knownii. Six are the most commoniii. (1) PETE, (2) HDPE, (3) V, (4) LDPE, (5) PP, (6) PS and all other are in group (7) OTHERSiv. The numbers above indicate the recycling # that you find on your food products that can be recycledb. Tuning Plastic Functionalityi. The functional groups of the monomer determine the polymer’s chemicalpropertiesii. H, CH3, C6H5, COOHiii. Common Properties: 1. Thermoplastics: flexible, melt, & shape2. Crystalline: tight packing, regular shape, & makes tougher plastics3. Amorphous regions: random orientation & more flexibleIII. Polymerizationa. Polyethylene (PE) from ethylene (ethane)b.c. Cheapest and simplest synthetic polymer – invented shortly before WW2d. Two Forms: High Density (HDPE) - #2 Low Density (LDPE) - #4e.f. The free radical is the unpaired electron and it’s looking for a partner. It’s very reactive on its own. The easiest electron to find is one of the electrons in that double bond of carbon. It grabs one and forms a new bond. Now there’s a bond between the radical and the carbon. The carbons are still bonded together as well. The radical is connected to one carbon and now there is a new unpaired electron on the other carbon and it wants a partner. Now it’s grabbing from the ethylene bond. Now there’s ANOTHER free radical on the right side of the ethylene bond (on the carbon). Then the process continues. There’s always going to be an odd man out until two radicals bump into each other and then they pair up and everyone is happy.IV. HDPE vs LDPEa. HDPE have straight linesb. LDPE has branches.c.d. HDPE can get closer together so they have more matter in less space and a higher density. Is also easier to recycle.e. There are specialized catalyst that control this. V. Addition Polymersa. HDPE, LDPE, PP, PVC, PSb. No monomer atoms are lost, they are only added to a growing chainc. There are no side productsd. MW = 10K to 100KVI. Intermolecular Forcesa. Hydrogen Bonding: is the electrostatic attraction between polar molecules that occurs when a hydrogen (H) atom bound to a highly electronegative atom such as nitrogen (N), oxygen (O) or fluorine (F) experiences attraction to some other nearby highly electronegative atom.b. Dispersion Forces: is an intermolecular attraction force that exists between all molecules. These forces are the result of the movement of electrons, which cause slight polar moments.c. Rigidity: d. Phenyl Group: know what it looks like