chapter12b.2008.forBB

chapter12b.2008.forBB - Chapter 12 Organic Chemicals and...

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Chapter 12: Organic Chemicals and Polymers Synthetic Organic Polymers A polymer polymer is a large molecule formed by linking a series of monomers monomers (smaller units). mono = one poly = many mer = part Polymers are also called macromolecules macromolecules . Classified by the way they respond to heat: thermoplastics thermoplastics soften and flow, then harden on cooling. thermosetting plastics thermosetting plastics initially soften, but then form a rigid structure that will not remelt.
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?? Synthetic Organic Polymers Addition Polymers Addition Polymers Monomer units add directly to each other. Ethylene (ethene) forms polyethylene polyethylene 1. Initiation A peroxide (R-O-O-R) breaks into two RO• and attacks a monomer: H H H H | | | | RO• + C – C RO – C – C• | | | | H H H H •• a free radical
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Addition Polymers Polymer growth. H H | | RO – C – C• | | H H H H H H | | | | + C – C RO – C – C | | | | H H H H •• H H | | – C – C• | | H H H H | | n CH 2 =CH 2 – C – C – | | H H n 2. Propagation 2. Propagation Addition Polymers 3. Termination 3. Termination Two radicals combine. H H | | •C – C – C | | H H H | – C • | H H H | | RO – C – C | | H H n – OR m H H | | RO – C – C – OR | | H H n+m 1000 – 50,000 units
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Identify monomer needed to make this polymer A B C D E Addition Polymers Polyethylene is the world’s most widely used polymer. High density polyethylene High density polyethylene (HDPE) Linear chains. High density, high molar mass. Hard and semirigid. Used in plastic milk jugs
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