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 | ±• | 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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Addition Polymers Low density polyethylene Low density polyethylene (LDPE) • Branched chains. • Cannot pack as closely. • Soft and pliable (sandwich bags) Cross -linked polyethylene linked polyethylene (CLPE) • Short -CH 2 - groups connect adjacent chains. • Very tough (soft-drink caps) Monomer Polymer Name CF 2 =CF 2 tetrafluoroethylene polytetrafluoroethylene (PTFE, Teflon ) F F | | –C ±–C ±– | | F F n Addition Polymers H CH 2 =C– polystyrene styrene H H | | | H n Substituted ethylene can be used:
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Addition Polymers Many other substituted ethylenes are important R Common Name Polymer Name Uses H ethylene polyethylene Squeeze bottles, films, toys, (Polythene) electrical insulation CH 3 propylene polypropylene Bottles, films, indoor-outdoor (Vectra, Herculon) carpet C l vinyl chloride poly(vinyl chloride) Floor tile, raincoats, pipe (PVC) CN acrylonitrile polyacrylonitrile Rugs, fabrics (Orlon, Acrilan) C 6 H 6 styrene polystyrene Food and drink coolers, (Styrofoam, Styron) building insulation OCOCH 3 poly(vinyl acetate) Latex paint, adhesives, vinyl acetate (PVA) textile coatings COOCH 3 poly(methyl methacrylate) Transparent objects, latex methyl methacrylate (PMMA, Plexiglass) paint, contact lenses H H C = C H R Natural and Synthetic Rubbers Latex Latex oozes from rubber trees (water/rubber particle emulsion).
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This note was uploaded on 07/15/2009 for the course CHE 131 taught by Professor Kerber during the Fall '08 term at SUNY Stony Brook.

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

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