Polymer Chemistry

Step 1: Understanding emulsion polymerization.
Emulsion polymerization is carried out in an aqueous medium where monomer droplets are dispersed in water with the help of emulsifiers. The reaction mainly occurs in micelles.
Step 2: Role of initiator.
The initiator used in emulsion polymerization must be soluble in water so that it can generate free radicals in the aqueous phase, which then enter the micelles to initiate polymerization.
Step 3: Analysis of options.
(A) Soluble in water: Correct — Common initiators like potassium persulfate are water soluble.
(B) Soluble in monomer: This is typical of solution or bulk polymerization.
(C) Insoluble in both: Cannot initiate polymerization effectively.
(D) Soluble in both: Not generally used in emulsion systems.
Step 4: Conclusion.
In emulsion polymerization, the initiator is generally water soluble, hence option (A) is correct.

Step 1: Understanding terylene production.
Terylene is the trade name for polyethylene terephthalate (PET), which is produced by condensation polymerization.
Step 2: Raw materials involved.
Terylene is manufactured using dimethyl terephthalate (DMT) or terephthalic acid along with ethylene glycol. DMT reacts with ethylene glycol to form PET.
Step 3: Analysis of options.
(A) PMMA: It is itself a polymer, not a raw material for PET.
(B) DMT: Correct — A key monomer used in terylene production.
(C) Glycerol: Used in alkyd resins, not PET.
(D) Bisphenol: Used in polycarbonate synthesis.
Step 4: Conclusion.
Dimethyl terephthalate (DMT) is used in the production of terylene, hence option (B) is correct.

Step 1: Understanding Terylene.
Terylene is the trade name for polyethylene terephthalate (PET), which is a synthetic fibre widely used in textiles and packaging materials.
Step 2: Chemical classification.
Polyethylene terephthalate is formed by condensation polymerization of ethylene glycol and terephthalic acid. The repeating ester linkage (–COO–) classifies it as a polyester.
Step 3: Analysis of options.
(A) Polyester: Correct — Terylene belongs to the polyester family.
(B) Polyamide: Includes nylons, not Terylene.
(C) Vinyl polymer: Derived from vinyl monomers, not applicable here.
(D) Acrylic Polymer: Based on acrylonitrile, not Terylene.
Step 4: Conclusion.
Terylene is a polyester, therefore option (A) is the correct answer.

Step 1: Understanding high molecular weight polymers.
High molecular weight polymers require rapid chain growth with minimal chain termination. Such conditions help in achieving long polymer chains with greater molecular mass.
Step 2: Role of polymerization techniques.
In emulsion polymerization, polymerization occurs in micelles where monomer concentration is high and termination reactions are minimized. This favors the formation of polymers with very high molecular weight.
Step 3: Analysis of options.
(A) Emulsion: Correct — It produces polymers with high molecular weight due to controlled radical concentration.
(B) Suspension: Produces moderate molecular weight polymers.
(C) Solution: Molecular weight is limited due to chain transfer to solvent.
(D) Dispersion: Not commonly used for very high molecular weight polymers.
Step 4: Conclusion.
Emulsion polymerization is preferred for synthesizing high molecular weight polymers, making option (A) correct.

Step 1: Understanding natural polymers.
Natural polymers are polymers that are found in nature and are produced by living organisms. They include substances like cellulose, starch, proteins, and natural rubber. These polymers are biodegradable and form the basis of many biological structures.
Step 2: Classification of given options.
Nylon, polycarbonate, and polypropylene are synthetic polymers manufactured through industrial chemical processes. Polysaccharides, on the other hand, are naturally occurring polymers composed of long chains of monosaccharide units.
Step 3: Analysis of options.
(A) Nylon: A synthetic polymer used in textiles and plastics.
(B) Polycarbonate: A synthetic polymer known for toughness and transparency.
(C) Polypropylene: A synthetic polymer widely used in packaging and plastics.
(D) Polysaccharides: Correct — Naturally occurring polymers such as starch and cellulose fall under this category.
Step 4: Conclusion.
Among the given options, polysaccharides are natural polymers, making option (D) the correct answer.

Step 1: Understanding vulcanization.
Vulcanization is a chemical process used to improve the properties of natural rubber by heating it with sulfur. This process increases elasticity, strength, durability, and resistance to temperature changes, making rubber suitable for industrial and commercial use.
Step 2: Historical background.
The discovery of vulcanization was made accidentally in 1839 by Charles Goodyear. He observed that rubber mixed with sulfur and heated became tougher and more elastic instead of sticky and brittle. This discovery revolutionized the rubber industry.
Step 3: Analysis of options.
(A) A.J. Heeger: Known for conducting polymers, not vulcanization.
(B) W.H. Carothers: Known for nylon and polymer research, not vulcanization.
(C) C. Goodyear: Correct — He discovered the vulcanization process of rubber.
(D) MacDiarmid: Known for conductive polymers, not rubber vulcanization.
Step 4: Conclusion.
The scientist associated with the discovery of vulcanization is Charles Goodyear, making option (C) the correct answer.

Step 1: Understanding the concept of macromolecules.
Macromolecules are very large molecules formed by the repetition of smaller structural units called monomers. The concept of macromolecules was revolutionary because, earlier, polymers were believed to be aggregates of small molecules rather than long-chain structures.
Step 2: Historical contribution.
Hermann Staudinger, a German chemist, introduced the term ``macromolecule'' in the early 1920s. He proposed that substances like rubber and cellulose consist of long-chain molecules with high molecular weight, which laid the foundation of modern polymer chemistry.
Step 3: Analysis of options.
(A) Karl Ziegler: Known for Ziegler–Natta catalysts but did not coin the term macromolecule.
(B) Giulio Natta: Contributed to stereochemistry of polymers, not the terminology.
(C) P.J. Flory: Developed polymer chemistry theory but did not introduce the term.
(D) Staudinger: Correct — He first coined the term ``macromolecules'' and is regarded as the father of polymer chemistry.
Step 4: Conclusion.
The word ``macromolecules'' was first coined by Hermann Staudinger, making option (D) the correct answer.