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.
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Is polystyrene a stereoregular polymer?
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 do you mean 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.
What are atactic polymers?
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.
What is syndiotactic polymer?
Syndiotactic – A syndiotactic polymer is one in which the pendant groups have a regular, alternating pattern along the hydrocarbon backbone chain. Gutta-percha, which is a type of permanent dental filling that is used in root canals because of its biological inertness, is an example of a syndiotactic polymer.
What catalyst produces stereoregular polymers?
Ziegler-Natta catalyst
Ziegler-Natta catalyst, any of an important class of mixtures of chemical compounds remarkable for their ability to effect the polymerization of olefins (hydrocarbons containing a double carbon–carbon bond) to polymers of high molecular weights and highly ordered (stereoregular) structures.
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 are examples of polymers?
Examples of synthetic polymers include nylon, polyethylene, polyester, Teflon, and epoxy. Natural polymers occur in nature and can be extracted. They are often water-based. Examples of naturally occurring polymers are silk, wool, DNA, cellulose and proteins.
What is atactic polymers give example?
Atactic – An atactic polymer is one in which the pendant groups are randomly arranged along the hydrocarbon backbone. Polystyrene is an example of an atactic polymer.
Is PVC Atactic?
PVC has mainly an atactic stereochemistry, which means that the relative stereochemistry of the chloride centres are random.
What is a stereoregular polymer?
Stereoregular Polymer. (also stereospecific polymer), any one of the polymers whose linear molecules consists of monomeric units having either identical spatial configurations or configurations that, while not identical, alternate in regular fashion. Stereoregular polymers of the first type include, for example, isotactic polymers’and 1,4-cis -…
What are some examples of shape memory polymers?
Shape Memory Polymers in Orthodontics There are numerous examples in which they replace metal wires in orthodontics: although the polymeric thread has mechanical properties of resistance to stress and fatigue lower than that of metal, it has a much lower aesthetic impact, increasing patient satisfaction. 2. Shape Memory Polymers in Bandages
Why is stereoregular polymerization important in catalysis?
In catalysis: Catalysis in stereoregular polymerization The importance of the concept of adsorption of reactants on the surface of catalysts has been greatly increased by the development of stereoregular polymerization processes—that is, methods that yield polymers whose molecules have definite three-dimensional patterns.
Do stereoregular polymethacrylamides have hydrogen bonds?
Stereoregular polymethacrylamides seem to have few hydrogen bonds in the solid state and in solution possibly due to the steric effect of the -methyl groups. Stereoregular and atactic N--methylbenzylmethacrylamide polymers were found to have some helical conformation in solution as indicated by ORD, CD, and U.V. measurements.