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
how to calculate pH value?


What is the purpose of zone refining One refining process is based on the fact that the first solid to crystallize in a two component system is usually purer than the liquid as

Ethyl bromide can be converted into ethyl alcohol using- Moist silver oxide or dry silver oxide?

I have a very difficult chemistry online assignment due in and I need help.

Analytical test of Oxalic acid or Polyprotic acid (a) The aqueous solution turns blue litmus red. (b) The aqueous solution includes effervescences along with NaHCO 3 . (c

Word root - IUPAC System of Naming Organic Compounds The word root represents the number of carbon atoms that are present in the chain. Table : Chain le

Illustrate the following observations:  (a) Cottrell's smoke precipitator is fitted at the mouth of the chimney used in factories.  (b) Ferric hydroxide sol. Gets coagulated

n-propyl acetate evaporates rapidly when exposed to air,but water does not.Explain

Q. What are the primary source of energy ? Oils and fats form an integral part of the dietaries the world over. In the body they are the primary source of energy. As you know,