Types of polymerization , Chemistry

Types of polymerization 

Sol. Types of polymerization: polymerization is a process in which the joining together of many small molecules to form very large molecule called polymer. Polymers are formed in different ways:

1 Addition or chain reaction polymerization: monomaniac units contain one or more double bonds which by intermolecular rearrangement may provide the molecule bifunctionality.

 2 condensation or step reaction polymerization: in condensation polymerization reaction take place in step wise manner and the polymer build up is slow. Step reaction polymerization reactions are mostly accompanied by the elimination of small molecules.

3 Ionic Polymerization mechanisms: it involves an attack on the electron pair of the monomer either by a positive or negative ion. Ionic polymerization mechanism is of two types.

(1)                         Cationic mechanism: in this initiation is done by a proton and the propagation carried out by a harmonium ion. Examples of monomers that can undergo cationic polymerization are methyl viny1 etc.

(2)                         Anionic mechanism: in this the attack on the electron pair of the monomer is done by an anion. The harmonium thus formed now propagates the chain growth by attack in the second monomer unit. Alkali metal amides alkaloids and hydroxides are used as initiators monomers capable of undergoing anionic polymerization include butadiene isoprene styrene acrylonitrile etc.

4 Coordination polymerization or Ziegler Natta polymerizations: in such polymerization reactions especially of olefins and dines are catalyzed by organ metallic compounds. The first step in this process in the formation of a monomer catalyst complex between organ metallic compound and the monomer.

 

 

Posted Date: 7/21/2012 8:37:36 AM | Location : United States







Related Discussions:- Types of polymerization , Assignment Help, Ask Question on Types of polymerization , Get Answer, Expert's Help, Types of polymerization Discussions

Write discussion on Types of polymerization
Your posts are moderated
Related Questions
short note on borazine

Rice bran Rice bran contains primarily insoluble fiber (cellulose) and soluble fiber (hemicellulose). Insoluble fiber adds bulk to the gastrointestinal (GI) track in humans cau

Line imperfection : Displacement with a curved boundary makes a mixed dislocation line at the boundary.

Bond enthalpies The most straightforward measure of the strength of a bond is the energy needed to break it. Estimates of such bond energies are usually obtained from thermo c

please tell the observation & inference, when ammonium phosphate (NH4)3PO4 undergoes charcoal cavity test & cobalt nitrate test.....

stuck on a chemistry assignment i need a way to include the elctron configuration and chemical properties of copper into a oral that is also a sales pitch.

working of electrolysis process? components of electrolysis process? advantages and disadvantages of electrolysis process?

Which one of the following is not the characteristic of Planck's quantum theory of radiation: (1)The energy is not absorbed or emitted in whole number or multiple of quantum

A solid substance with a mass of 200g is at its melting temperature in a calorimeter. While the substance changes from a solid to a liquid at the same temperature, the 400-gram mas

Post-harvest treatments Certain post-harvest treatments to fruits and vegetables can bring down spoilage significantly. A wide range of chemicals used to control post-harvest d