What is meant by Stereoregular polymer?
What is meant by Stereoregular polymer?
polymers are referred to as stereoregular—that is, polymers having an ordered arrangement of pendant groups along the chain. A polymer with a random orientation of groups is said to be atactic.
Why is Stereoregularity important in polymers?
Polystyrene: Syndiotactic Syndiotactic polystyrene (sPS), a stereoregular polymer, is an important engineering thermoplastic due to its properties such as high melting point, high crystallization rate, excellent chemical resistance, etc.
What are atactic polymers give its structure?
An atactic polymer is defined as a linear polymer containing asymmetrically substituted carbon atoms in the repeating unit in the main chain, a planar projection of whose structure has the same substituents situated randomly to one side or the other of the main chain.
Which of the following is an example of Stereoregular polymer?
Stereoregular polymers include isotactic polypropylene, syndiotactic polyvinyl chloride, and stereoregular butadiene rubber, which are produced industrially, and certain natural polymers, such as cellulose and natural rubber.
How are stereoregular polymers achieved?
Stereoregular polymers can be produced when the stereochemistry at the penultimate unit of the polymer chain induces stereospecific addition of monomers at the prochiral reactive center.
What is the meaning of Stereoregular?
Definition of stereoregular : of, relating to, or involving stereochemical regularity in the repeating units of a polymeric structure.
What is the difference between atactic and isotactic polymers?
The key difference between atactic isotactic and syndiotactic polymer is that atactic polymers have their substituents in a random manner and isotactic polymers have their substituents in the same side, whereas the syndiotactic polymers have their substituents in an alternating pattern.
What is atactic polymer example?
Atactic polymers are technologically very important. A good example is polystyrene (PS). If a special catalyst is used in its synthesis it is possible to obtain the syndiotactic version of this polymer, but most industrial polystyrene produced is atactic.
Which of the following is the condition for ideal copolymerization?
Explanation: A copolymerization is said to be an ideal copolymerization when the chain radicals have equal preference to add one of the monomers over the other.
What is isotactic polymer?
Isotactic polymers are composed of isotactic macromolecules (IUPAC definition). In isotactic macromolecules all the substituents are located on the same side of the macromolecular backbone. An isotactic macromolecule consists of 100% meso diads. Polypropylene formed by Ziegler–Natta catalysis is an isotactic polymer.
What is the difference between atactic and isotactic polypropylene?
Atactic polypropylene is a soft, rubbery polymer, while isotactic polypropylene is strong and hard with excellent resistance to stress, cracking, and chemical reaction. Syndiotactic polypropylene has only recently been made on a large scale. It is somewhat softer than the isotactic polymer, but also tough and clear.
What is an isotactic polymer?
An isotactic polymer that contains two chiral or prochiral atoms with defined stereochemistry in the main chain of the configurational base unit. From: Comprehensive Polymer Science and Supplements, 1989.