Question

Name the phenol-formaldehyde polymers.

Answer 1

Hint: Polymers are the high molecular mass compounds obtained by regularly joining structural units. The simple reactive molecules from which the repeating structural units are derived are called monomers. The use of polymers in the manufacture of toys, synthetic clothing materials, packaging bags, automobile tyres, plastic buckets, cups and saucers etc. has completely revolutionized daily life as well as the industrial scenario.

Complete answer:
Bakelite is the phenol-formaldehyde polymer. It is obtained when phenol reacts with formaldehyde in presence of an acid or dilute alkali as a catalyst. The reaction involves the formation of the methylene $\left( { - C{H_2}} \right)$ bridges in ortho, para or both ortho and para positions. As a result, either linear or cross-linked material is obtained. The reaction is difficult to control because condensation of ortho and para hydroxy methyl phenol leads to the formation of polymeric products. The final product is a dark, brittle and cross-linked product which is the Bakelite.
Thus, Bakelite is the phenol-formaldehyde polymer.

Note:
Polymers are divided into categories based on their origin.
Natural polymers: These are the complex compounds of high molecular mass obtained from natural sources. Examples are proteins, starch, cellulose, nucleic acids, gums etc.
Synthetic polymers: These are man-made polymers. There is an endless variety of such polymers. Such important examples are PVC, Teflon, Nylon, Bakelite, synthetic rubber etc.
Semisynthetic polymers: These are made by modifying the properties of natural polymers. Some important examples are nitrocellulose, cellulose acetate etc. Gun cotton which is cellulose nitrate is used in making explosives.