Which initiators are used in free radical polymerization?
The most widely used initiators produce free radicals (reactive atoms or groups of atoms that contain odd numbers of electrons); examples include peroxides and aliphatic azo compounds used to polymerize vinyl chloride, methyl methacrylate, and other monomers.
What are the polymerization initiators?
Thermal polymerization initiators are compounds that generate radicals or cations upon exposure to heat. The conventional photopolymerization initiators generate free radicals upon light irradiation, and the resulting radical starts the polymerization process. Typical initiators are represented by benzoin derivatives.
What are the free radical initiators?
In chemistry, radical initiators are substances that can produce radical species under mild conditions and promote radical reactions. These substances generally possess weak bonds—bonds that have small bond dissociation energies.
Which monomers are suitable for free radical polymerization?
Solution radical polymerization FRP enables the synthesis of high-molecular-weight polymers from a variety of monomers. FRP is a key synthesis route for obtaining a wide variety of different polymers and material composites. Acrylates and methacrylates are among the most commonly used monomers in FRP.
Which catalyst is used for free radical polymerization?
When radical polymerization is desired, it must be started by using a radical initiator, such as a peroxide or certain azo compounds. The formulas of some common initiators, and equations showing the formation of radical species from these initiators are presented below.
Which catalyst is used in the coordination polymerization?
Ziegler–Natta catalyst
Which catalyst is commonly used in coordination chain polymerization? Explanation: A Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, is a catalyst used in the synthesis of polymers of 1-alkenes (alpha-olefins).
Why is AIBN a good radical initiator?
AIBN is safer to use than benzoyl peroxide (another radical initiator) because the risk of explosion is far less. However, it is still considered as an explosive compound, decomposing above 65 °C.
What is free radical addition polymerization?
Free-radical polymerization (FRP) is a method of polymerization, by which a polymer forms by the successive addition of free-radical building blocks. Free radicals can be formed by a number of different mechanisms, usually involving separate initiator molecules.
Why is it impossible to polymerize propylene using free radical polymerization?
Polypropylene cannot be synthesized using free radical polymerization since you cannot make a stable propagating species with propylene. ZN polymerization is an example of chain growth since monomers are added one at a time to a growing chain that is tethered to an active catalyst site.
What is free radical polymerization example?
For example, 40 to 45 percent of all polymers and synthetic rubbers are produced via a free radical polymerization process. This includes polystyrene, poly(methyl methacrylate), polyvinyl acetate, polyvinyl chloride, polybutadiene, polychloroprene and polyethylene among many other large volume polymers and elastomers.