snehal shamrao padmagiriwar

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Step Growth Polymerization


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TOPIC : Step-growth Polymerization B y :- Snehal S. Padmagiriwar

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Polymer The word polymer is derive by dividing the polymer into two parts , poly means many mer means parts. Polymer is define as a chemical substances of a high molecular mass formed by the combination of large number of simple molecules called monomers. n Monomer Polymer POLYMER Poly Mer Many Parts

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Polymerization The process by which the monomers gets combine and transformed into polymer is know as polymerization. The well know example of polymer is the preparation of polyethene from ethylene as a monomer molecule. It is express as follows: n CH 2 = CH 2 Polymerization (-CH 2 -CH 2 -) n Ethylene Polyethylene Where n = degree of polymerization

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Classification of polymer The Polymer has a broad classification, let us classified the polymer on the basis of polymerization process or mode of polymerization.   Polymerization process       Chain polymer Condensation polymer (Addition polymer) (Step growth polymer)       Homopolymer Copolymer

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Chain Polymer : It is a type of polymer in which the monomer molecules contains double or triple bond. It is farther classified into two main types: Homopolymer : When two same monomer molecules reacts with each other then this type of polymer is known as homopolymer . Example , n CH 2 = CH 2 Polymerization (-CH 2 -CH 2 -) n Ethylene Polyethylene   Copolymer : When two different monomer molecules reacts with each other then this type of polymer is known as copolymer. Example , n CH 2 =CH-CH= CH 2 + Ph-CH=CH 2 Polymeri . (-CH 2 –CH=CH- CH 2 -CH-Ph-CH 2 -) n   1,3- Butadiene Styrene Butadiene styrene rubber   (BUNA – S)

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Condensation Polymer : It is a type of polymer in which monomer molecules reacts and condensed. Small molecule like water or hydrochloric acid can be remove. Example, n NH 2 –(CH 2 ) 6 –NH 2 + n COOH-( CH 2 ) 4 -COOH hexamethylenediamine adipic acid polymerization (-H 2 O)   -( NH –(CH 2 ) 6 –NH-CO-( CH 2 ) 4 -CO) n - Nylon 66

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Step-growth polymerization Step-growth polymerization is a type of polymerization in which bifunctional or multifunctional monomer react to form first dimer then trimer , long chain polymer. The growth of polymer is occur in a stepwise manner, so it is called as step growth polymerization. As small molecule will be condensed during the reaction. so it is also called as a step polycondensation reaction. CH 3 –OH + HO-CO-CH 3 CH 3 –O-CO- CH 3 + H 2 O Methanol acetic acid ester

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examples (1) When a pair of bifunctional monomer ( dicarboxylate , dialcohol , diamine ) undergo polycondensation reaction,   CH 2 –OH + R-Cl 2 - HCl CH 2 – ORCl - HCl CH 2 –O-R CH 2 –OH dichloro CH 2 –OH CH 2 –O Ethylenediol alkyl cyclic product (2) When ethylene glycol react with acetic acid to form diester , with the removal of small amount of water molecule. CH 2 –OH + CH 3 –COOH CH 2 –O–CO- CH 3 CH 2 –O-CO- CH 3 CH 2 –OH -H 2 O CH 2 –OH -H 2 O CH 2 –O-CO- CH 3

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(3) When ethylene glycol react with adipic acid to form diester , with two active centre. As it has two active centre so this reaction will continue. CH 2 –OH + CH 2 –CH 2 –COOH CH 2 –O-CO-CH 2 –CH 2 –CH 2 –CH 2 –COOH CH 2 –OH CH 2 –CH 2 –COOH CH 2 –OH Adipic acid   CH 2 –O-CO-CH 2 –CH 2 –CH 2 –CH 2 –COOH CH 2 –O-CO-CH 2 –CH 2 –CH 2 –CH 2 –COOH Diester   (4) Self Polycondensation Reaction : When both reactive functional group is present on the same monomer it gives rises to self condensation reaction. n NH 2 -(CH 2 ) 5 -COOH Polymerization -(NH -(CH 2 ) 5 -CO) n - Enanthic acid Polyenanthic acid

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Conclusion (1) Each polymer is bifunctional . (2) The polymer form is an active polymer. (3) Each reaction is followed by same type of mechanism ie . Condensation reaction mechanism. (4) The reaction take place in a stepwise manner and terms as Step-growth polymerization.

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properties   * High bond strengths * Rigid polymer chains * High molecular weight * High cross-linking * Strong dipole-dipole interaction * Strong hydrogen bond interactions

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applications Circuit boards Aircraft components Coatings on cookware Engine part Coating of electronic device Microelectronic devices  

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REFERENCE Polymer Chemistry , By, Govarikar   (2) Polymer By, Jagdamba Singh  

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Thank You!

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