What is a Free Radical Polymerization?
A free Radical Polymerization is a polymerizing approach by which successive addition of free radicals takes place to form a polymer unit. It is a type of chain-growth polymerization, with a cationic, anionic and coordination polymerization. It is an essential technique for obtaining different polymers and material composites. It was used to get 40 billion of 110 billion polymers in the United States in 2001.
This section will discuss the Free Radical Polymerization, Mechanism of Free Radical Polymerization, Thermodynamics of Free Radical Polymerization, Applications of Free Radical Polymerization in detail.
Table of Content
- Free Radical Polymerization
- Mechanism of Free Radical Polymerization
- Initiation of Free Radical
- Propagation of Free Radical
- Termination of Free Radical
- Thermodynamics of Free Radical Polymerization
- Applications of Free Radical Polymerization
- Frequently Asked Questions – FAQs
Free Radical Polymerization
A free Radical Polymerization is a polymerizing approach by which successive addition of free radicals takes place to form a polymer unit. It is a type of chain-growth polymerization, with a cationic, anionic and coordination polymerization. Free Radical Polymerization occurs in three steps, i.e. Initiation, Propagation and Termination.
Free Radical Polymerization is an essential technique for obtaining different polymers and material composites. It was used to get 40 billion of 110 billion polymers in the United States in 2001.
Mechanism of Free Radical Polymerization
Free Radical Polymerization occurs in three steps, i.e.
- Initiation of Free Radical
- Propagation of Free Radical
- Termination of Free Radical
Initiation of Free Radical
Initiation is the foremost step in the polymerization process. An active centre is generated in this process to begin polymerization. All the monomers are not liable for the initiation process.
- One or two radicals are created from the initiating molecules in the first step.
- Radicals are transferred from the initiating molecules to the monomer units in the second step.
Propagation of Free Radical
A polymer spends most of its time expanding its chain length or propagating. After initiation of free radical, it attacks another monomer subunit. It uses one of the pi bond electrons to form a stable bond with another carbon atom. The other electron returns to the second carbon atom, turning the whole molecule into a radical.
After initiation, the chain propagates until no monomer is left or termination starts.
Termination of Free Radical
Termination is the final step in the polymerization process. Termination occurs in different stages. If longer chains are expected, the initiator concentration should be less; otherwise, many short chains will form.
Thermodynamics of Free Radical Polymerization
In chain-growth polymerization, the equilibrium position can be determined by the thermodynamics of the polymerization process. The tendency of polymeric reaction is determined by calculating Gibbs free energy (ΔGp).
- If ΔGp < 0, polymerization will occur.
- If ΔGp > 0, depolymerization will occur.
Thermodynamic equation states that,
ΔG = ΔH – TΔS,
A negative enthalpy and an increasing entropy will favour polymerization.
- Polymerization is favoured at low temperatures, i.e. TΔSp is small.
- Depolymerization is favoured at high temperatures, i.e. TΔSp is large.
- When the rate of polymerization = rate of depolymerization, equilibrium is attained.
- This temperature is known as the ceiling temperature (Tc).
Applications of Free Radical Polymerization
Free Radical Polymerization has lots of applications. It is an essential technique for obtaining different polymers and material composites. It was used to get 40 billion of 110 billion polymers in the United States in 2001.
- It is used in synthesizing polystyrene and elastomers.
- It is used in synthesizing chemical surfactants, lubricants
- It is used in manufacturing cardiovascular stents.
- It is used in synthesizing nanocomposite hydrogels.
Frequently Asked Questions on Free Radical Polymerization
What is a polymer?
A polymer is a natural or synthetic substance made up of giant molecules called macromolecules that are, in turn, made up of many repeating subunits of monomers.
What is free-radical polymerization?
A free Radical Polymerization is a polymerizing approach by which successive addition of free radicals takes place to form a polymer unit. It is a type of chain-growth polymerization, with a cationic, anionic and coordination polymerization. Free Radical Polymerization occurs in three steps, i.e. Initiation, Propagation and Termination.
What are the different steps of free radical polymerization?
Free Radical Polymerization occurs in three steps, i.e.
- Initiation of Free Radical
- Propagation of Free Radical
- Termination of Free Radical
Explain the thermodynamics of a free radical polymerization?
In chain-growth polymerization, the equilibrium position can be determined by the thermodynamics of the polymerization process. The tendency of polymeric reaction is determined by calculating Gibbs free energy (ΔGp).
ΔG = ΔH – TΔS
- If ΔGp < 0, polymerization will occur.
- If ΔGp > 0, depolymerization will occur.
What are the applications of free radical polymerization?
Free Radical Polymerization has lots of applications. It is an essential technique for obtaining different polymers and material composites.
- It is used in synthesizing polystyrene and elastomers.
- It is used in synthesizing chemical surfactants, lubricants
- It is used in manufacturing cardiovascular stents.
- It is used in synthesizing nanocomposite hydrogels.
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