Polym._reactions_S09 - Basic Definitions Polymer Large...

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Polymer Large molecule consisting of many relatively small chemical units covalently linked into a chainlike structure Monomer Any substance capable of chemical combination into polymer chains Repeat Unit Simplest sequence repetitively occurring in the polymer Degree of polymerization (DP) Total number of repeating units; related to chain length and molecular weight. A given polymer sample contains varying lengths of chains; hence, we normally refer to average degree of polymerization . Calculated from DP = M/M 0 , where M = appropriate molar mass of polymer and M 0 is the molar mass of repeating unit. End groups These are structural units that terminate the polymer chains. Where speciFed they are shown outside the brackets. Basic DeFnitions
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Examples of Simple Polymers [See Table 28.1, p1235 of Bruice] CH 2 CH CH 3 propylene polypropylene CH 2 C CH 3 CH 3 isobutylene polyisobutylene CH 2 H CO 2 CH 3 CO 2 CH 3 CO 2 CH 3 methyl acrylate poly(methyl acrylate) CH 2 CH 3 CO 2 CH 3 CO 2 CH 3 CO 2 CH 3 methyl methacrylate poly(methyl methacrylate CH 2 =CH—CH=CH 2 butadiene polybutadiene CH 2 CH CH 3 CH CH 2 isoprene polyisoprene H 2 NCH 2 COOH H N OH H O N H O polyglycine glycine polypeptide H 2 N CH R COOH H N OH H O N H O R R ! -aminoacid poly( ! -aminoacid) polypeptide HO CH R COOH H O OH R O O R O ! -hydroxyacid poly( ! -hydroxyalkanoate) polyester CH 2 CH Ph Ph Ph styrene polystyrene
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Classifcation (1) Condensation Polymers: Composition dependent Step-Growth Polymers - Mechanism based. Preferred by most practitioners. The molecular formulas of the structural units lack certain atoms present in the monomers from which the polymers are made or to which they may be degraded. May be formed from monomers bearing 2 or more reactive groups that react to eliminate a by-product. Example: polyamides (such as nylon) —NHCH 2 CH 2 CH 2 CH 2 CH 2 CH 2 NH—COCH 2 CH 2 CH 2 CH 2 CO— (2) Addition Polymers: Composition and reaction-type based More general name: Chain growth polymers - mechanism based
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This note was uploaded on 05/13/2010 for the course CHEM ORGANIC CH taught by Professor Dotsevisogah during the Spring '09 term at Cornell University (Engineering School).

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Polym._reactions_S09 - Basic Definitions Polymer Large...

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