Question

The polymer which does not contain halogen is (a) neoprene (b) glyptal (c) PVC (d) Teflon

Short answer

Answer: (b) glyptal

Step-by-step solution

Understand the structure of neoprene

Neoprene is a synthetic polymer made by polymerizing chloroprene. The structure of chloroprene is as follows: C\(_{4}\)H\(_{5}\)Cl As we can see, there is a halogen (chlorine) present in the structure of neoprene.

Understand the structure of glyptal

Glyptal is an alkyd resin, a type of polyester that is made by condensing polyols and dibasic acids. The general structure of glyptal does not contain any halogen atoms.

Understand the structure of PVC

PVC, or polyvinyl chloride, is a synthetic plastic polymer made by polymerizing vinyl chloride. The structure of vinyl chloride is as follows: C\(_{2}\)H\(_{3}\)Cl PVC contains a halogen (chlorine) in its structure.

Understand the structure of Teflon

Teflon is a brand name of a polymer called polytetrafluoroethylene (PTFE). The structure of PTFE is as follows: (CF\(_{2}\))\(_{n}\) Teflon contains a halogen (fluorine) in its structure.

Determine which polymer does not contain halogen

Out of the given polymers, only glyptal (option b) does not contain any halogen atoms in its structure. Hence, the correct answer is: (b) glyptal

Key concepts

Understanding Neoprene

Neoprene, also known as polychloroprene, is a type of synthetic rubber that is valued for its stability and resistance to various environmental factors such as oils, chemicals, and temperature changes. It is produced by polymerizing chloroprene, a monomer which, as its name suggests, contains chlorine—a halogen element. The presence of chlorine gives neoprene a range of beneficial properties, including durability and elasticity, but also categorizes it as a halogen-containing polymer.

Despite its wide range of applications, like in wetsuits and laptop sleeves, neoprene is not halogen-free. When studying polymers for their halogen content, it's crucial to look closely at their molecular structures to identify the presence of elements like fluorine, chlorine, bromine, and iodine—the elements commonly recognized as halogens.

Glyptal's Halogen-Free Composition

Glyptal is an alkyd resin that belongs to the polyester family of polymers and serves as an excellent example of a halogen-free material. It is created through a chemical reaction called condensation polymerization between polyols (alcohol with multiple -OH functional groups) and dibasic acids (acids with two carboxylic acid -COOH groups).

The durability and insulating properties of glyptal make it ideal for use in protective coatings and electrical insulations. Importantly, its structure does not incorporate any halogen atoms, qualifying glyptal as halogen-free. This feature is particularly desirable for applications where less corrosive smoke and toxicity are required in the event of combustion, making glyptal a safer polymer option in many industries.

Polyvinyl Chloride (PVC) and Its Halogen Content

Polyvinyl chloride (PVC) is a widely used plastic polymer that comes into play in various applications, from construction materials like pipes and window frames to healthcare products and everyday items like credit cards. PVC's structure is based on the polymerization of vinyl chloride monomers, clearly indicating the presence of chlorine in its backbone.

As one of the most versatile plastics, PVC's halogen content lends it properties such as enhanced flame resistance. However, it also raises concerns about environmental impact and toxicity, especially when considering its disposal and the release of dioxins during combustion. Although useful for many applications, PVC does not meet the criteria for halogen-free materials.

Polytetrafluoroethylene (PTFE) - A Halogenated Polymer

Polytetrafluoroethylene (PTFE), commonly known as Teflon, is another example of a halogenated polymer. This material is famed for its non-stick properties which make it ideal for cookware coatings and also for its high resistance to heat and chemical agents. The monomer unit of PTFE consists entirely of carbon and fluorine, the latter being another member of the halogen family.

PTFE is often highlighted for its almost unparalleled chemical stability, which can be attributed to the strong carbon-fluorine bonds. While these bonds contribute to PTFE's outstanding performance characteristics, they also confirm that PTFE is not a halogen-free material. When searching for halogen-free polymers, PTFE does not fit the description due to its substantial fluorine content.