polymers and polymerization.

precise but complete and authentic description of polymers.

1. POLYMERS AND POLYMERIZATION PRESENTATION BY: AGHA ABDUL AZIZ

2. POLYMER Large molecules formed by combination of small molecules (monomers) are called as polymers. E . g polyethylene , proteins etc. POLYMERIZATION The process of formation of polymer from its monomer is called as polymerization. Polymerization starts when a reactive site on one of the monomers is produced . For production of reactive site ,initiator is used.

3. CLASSIFICATION OF POLYMERS BASIS OF CLASSIFICATION Polymers are classified on the basis of; Sources of polymers Thermal behavior Mechanism of polymerization Structure of polymer

4. CLASSIFICATION ON BASIS SOURCES NATURAL POLYMERS SEMI-SYNTHETIC POLYMERS SYNTHETIC POLYMERS Polymers that are isolated from natural sources. These polymers are synthesized from natural polymers. Polymers that are synthesized by chemical reactions in laboratories and industries. E . g cellulose, starch, etc. E . g cellulose acetate , rayon etc. E . g nylon, polyethylene etc.

5. Classification on basis of thermal properties thermoplastics Thermosetting polymers Polymers that can be heat softened. Polymers that are heat resistant and can not be heat softened. E . g polystyrene. E .g epoxy-phenol-formaldehyde resin.

6. CLASSIFICATION ON THE BASIS OF MECHANISM Chain- growth polymerization Step-growth polymerization Type of polymerization in which unsaturated monomer s add onto the active site of growing polymer chain one at a time. Addition of each monomer regenerates the active site. It is also called as addition polymerization. It is a type of polymerization in which a stepwise reaction between bi functional and multifunctional monomers occurs. Bi functional monomer Monomer with two reactive sites.

7. Types of polymeriztion Free radical polymerization Anionic polymerization Cationic polymerization initiated by a free radical. E.g. Initiated by an anion . E.g. Initiated by a cat-ion. E.g.

8. RING OPENING POLYMERIZATION ( ROP ) AND ATOM TRANSFER RADICAL POLYMERIZATION ( ATRP ). ROP is a form of chain-growth  polymerization , in which the terminal end of a polymer chain acts as a reactive center where further cyclic monomers can react by  opening  its  ring  system and form a longer polymer chain. E.g. ATRP Atom transfer Radical polymerization . Halogen transfer through metal complex inducing reversible heterolysis, Resulting in the formation of reversible free radical which then propagate polymerization.

9. MECHANISM of ATRP.

10. CLASSIFICATION BASED UPON POLYMER STRUCTURE Homo chain polymers Hetero chain polymers copolymers Polymers which contain only one atom in their backbone. Polymers that contain more than one type of atom in the back bone. Polymers with two different repeating units.

11. DIFFERENCE BETWEEN BRANCHED HOMO POLYMER AND BLOCK COPOLYMER. Branched homopolymers have same repeat units in the branch as in the backbone. Graft copolymers have different repeat units in the branch. Graft copolymer is prepared by polymerizing a monomer in the presence of fully formed polymer of another monomer.

12. TECHNIQUES OF POLYMERIZATION Homogenous polymerization. Heterogeneous polymerization. Polymerization that occurs in a homogenous mixture. Polymerization that occurs in a heterogeneous mixture. Bulk polymerization. Solution polymerization. Emulsion polymerization. Suspension polymerization. Monomer is in liquid form ,in which initiator and catalyst are dissolved. Monomer initiator and catalyst are dissolved in the suitable solvent.

13. SYNTHESIS OF TMC MY NEXT PRESENTATION COMING SOON.