Some Important Polymers — Core Principles

Core Principles

Important polymers are large molecules formed from repeating smaller units called monomers, crucial for various industries and daily life. They are broadly classified by their synthesis method: addition polymerization (monomers add without losing atoms, e.

g., polythene, PVC, Teflon) and condensation polymerization (monomers combine with the elimination of small molecules like water, e.g., Nylon, Dacron, Bakelite). Key addition polymers include Polythene (LDPE for flexible items, HDPE for rigid ones), PVC (pipes, insulation), Teflon (non-stick coatings), and various synthetic rubbers like Buna-S and Buna-N.

Important condensation polymers include Polyamides (Nylon-6,6, Nylon-6 for fibers and plastics), Polyesters (Dacron/Terylene for fabrics, Glyptal for paints), and Phenol-Formaldehyde resins (Bakelite for electrical switches).

Understanding the specific monomer(s), polymerization type, properties, and uses for each polymer is essential for NEET, as questions often test direct recall and application of this knowledge.

Important Differences

vs Addition Polymers vs. Condensation Polymers

Aspect	This Topic	Addition Polymers vs. Condensation Polymers
Mechanism	Monomers add to each other sequentially without the loss of any atoms.	Monomers combine with the elimination of small molecules (e.g., $H_2O$, $NH_3$, $CH_3OH$).
Monomer Type	Usually unsaturated compounds (alkenes, alkynes, dienes) or cyclic ethers.	Bifunctional or polyfunctional compounds (e.g., diols, dicarboxylic acids, diamines).
Empirical Formula	The empirical formula of the polymer is the same as that of the monomer.	The empirical formula of the polymer is different from that of the monomers due to the loss of small molecules.
By-products	No by-products are formed.	Small molecules are formed as by-products.
Examples	Polythene, PVC, Teflon, Polypropylene, Natural Rubber.	Nylon-6,6, Terylene (Dacron), Bakelite, Melamine-formaldehyde resin.

The distinction between addition and condensation polymerization is fundamental to understanding polymer synthesis. Addition polymerization involves the direct joining of unsaturated monomers without any loss of atoms, leading to a polymer with the same empirical formula as its monomer. In contrast, condensation polymerization involves the reaction of bifunctional or polyfunctional monomers, resulting in the elimination of small molecules like water and a polymer with a different empirical formula. This difference dictates the types of monomers used, the reaction conditions, and ultimately the structure and properties of the resulting polymer.