Class 12 Chemistry - Chapter Polymers NCERT Solutions | How does the presence of double bonds in
How does the presence of double bonds in rubber molecules influence their structure and reactivity?
Natural rubber is a linear cis-1,4- polyisoprene in which double bonds are present between C2 and C3 of isoprene units.
The cis configuration about double bonds does not allows the chains to come closer for effective intermolecular attraction due to weak intermolecular attractions. Therefore, the natural rubber has coiled structure and shows elasticity and is non crystalline.
On the other hand, all trans configurations occur in gutta-percha (synthetic rubber) which is trans-polyisoprene. These zig-zag chains pack more closely in gutta-percha and hence it is highly crystalline, non elastic, more hard and brittle than rubber.
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