What is meant by 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. Isotactic polymers are usually semicrystalline and often form a helix configuration.

What is an example of isotactic polymer?

Commercial polypropylene is an important example of an isotactic polymer. Atactic and syndiotactic forms of this polymer can also be prepared by controlling the polymerization conditions. Atactic polypropylene is an amorphous, tacky polymer with no commercial importance.

What is isotactic and syndiotactic polymer?

If all the methyl groups lie on the same side of the chain, the polymer is called isotactic. If the methyl groups alternate in a regular fashion from one side of the chain to the other, the polymer is syndiotactic. The tacticity of a polymer can have a dramatic effect on its physical properties.

What is the meaning of isotactic?

: having or relating to a stereochemical regularity of structure in the repeating units of a polymer — compare atactic.

What are properties of polymers?

Some of the useful properties of various engineering polymers are high strength or modulus to weight ratios (light weight but comparatively stiff and strong), toughness, resilience, resistance to corrosion, lack of conductivity (heat and electrical), color, transparency, processing, and low cost.

Why does Tacticity affect polymer properties?

The explanation for this behavior lies in the added steric repulsion to rotation due to the presence of the asymmetric double-sided groups on alternate chain backbone atoms, which increases the stiffness of the polymer significantly compared to an atactic polymer.

Which are natural polymers?

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. Vulcanized rubber is a synthetic (man-made) polymer, while pectin is an example of a natural polymer.

What are 3 properties of polymers?

A1.1 PHYSICAL PROPERTIES Physical properties of polymers include molecular weight, molar volume, density, degree of polymerization, crystallinity of material, and so on.

What are two types of polymers?

Polymers are of two types: naturally occurring and synthetic or man made.

Which is not polymer?

If the forming units of the given biological macromolecules are considered, proteins are formed of amino acids joined one after the other, polysaccharides are formed from monosaccharides, nucleic acids are formed of nucleotides. Only lipids are not made of uniform components, that is, they are not polymeric.

Which is the best description of an isotactic polymer?

Isotactic and syndiotactic 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. Stereoregular polymers are usually high-strength materials because the uniform structure leads….

What’s the difference between a Chem and an isotactic?

(Chemistry) chem (of a stereospecific polymer) having identical steric configurations of the groups on each asymmetric carbon atom on the chain. Compare syndiotactic (of a polymer) having the same configuration at successive, regularly spaced positions.

Which is the best description of a syndiotactic polymer?

Isotactic and syndiotactic 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. Stereoregular polymers are usually high-strength materials because the uniform structure leads to close…

How are methyl groups arranged in isotactic polypropylene?

(In isotactic polypropylene, all the methyl [CH 3] groups are arranged along the same side of the polymer chain.) It is produced at low temperatures and pressures using Ziegler-Natta catalysts. Isotactic and syndiotactic polymers are referred to as stereoregular—that is, polymers having an ordered arrangement of pendant groups along the chain.