Synthetic polymers are classified by their sequence of synthesis as chain growth or step growth polymers. Chain growth polymers are produced by chain reaction polymerization in which an initiator adds to a carbon-carbon double bond of a vinyl monomer to yield a reactive intermediate. The intermediate reacts with a second monomer to yield a new intermediate which reacts with a third unit and so on. The initiator may be a radical or an acid or an anion. Acid catalysed polymerization is effective in case of vinyl monomers having electron donating groups. Anionic polymerization requires the presence of electron withdrawing groups. One of the important catalysts used in polymerization is Ziegler-Natta catalyst (triethyl aluminium and titanium tetrachloride). One of the important aspects of Zeiglar-Natta catalysed polymers is that they are stereo-chemically controllable. Three forms (i) isotactic (ii) syndiotactic and (iii) atactic can be produced Vinylidene chloride \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CCl}_{2}\) does not polymerize in isotactic, syndiotactic or atactic forms because (a) it contains electronegative chlorine atoms. (b) it has sp \(^{2}\) hybridized carbon. (c) it is a planar molecule. (d) the polymer formed has no chiral centre

Step by step solution

01

Understand the three forms of polymer structures - isotactic, syndiotactic, and atactic

Isotactic polymers have all their substituents on the same side of the polymer backbone. Syndiotactic polymers have their substituents alternating sides along the backbone. Atactic polymers have a random arrangement of substituents along the backbone.

02

Analyze the structure of Vinylidene Chloride (H2C=CCl2)

The molecular formula for Vinylidene chloride is given as H2C=CCl2. The carbon atoms are sp2 hybridized, which makes the molecule planar. The molecule has two electronegative chlorine atoms attached to one carbon atom, and two hydrogen atoms attached to another carbon atom.

03

Evaluate the given options

Option (a): It contains electronegative chlorine atoms. - While it is true that the molecule contains electronegative chlorine atoms, this does not necessarily preclude it from forming isotactic, syndiotactic, or atactic polymers. Option (b): It has sp2 hybridized carbon. - The sp2 hybridization does impact the way vinylidene chloride is polymerized, but it does not explain why it can't form isotactic, syndiotactic, or atactic polymers. Option (c): It is a planar molecule. - The molecule being planar does not directly prevent it from forming isotactic, syndiotactic, or atactic polymers. Option (d): The polymer formed has no chiral centre. - To have isotactic, syndiotactic, or atactic polymers, we need chiral centers on the carbon atoms of the monomer. In the case of vinylidene chloride, both carbon atoms have two identical groups attached (hydrogen or chlorine), meaning that they aren't chiral centers. This explains why it does not polymerize in isotactic, syndiotactic, or atactic forms.

04

Choose the correct answer

Based on the analysis in the previous steps, we can conclude that the correct answer is (d) the polymer formed has no chiral centre.

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