Q.The monomer of natural rubber is _______.

Elastomers are popularly called rubbers, used in balloons, shoe soles, tyres, surgeon's gloves and garden hoses. Natural rubber's monomer is isoprene (2-methyl-1,3-butadiene, CH2=C(CH3)-CH=CH2); natural rubber is a high molecular mass linear addition polymer of isoprene (polyisoprene), with molecular mass ranging from about 130,000 to 340,000 u (roughly 2000-5000 monomer units per chain). Its double bonds are locked in the cis configuration, and the resulting chains are held together only by weak van der Waals forces, giving a loosely coiled structure that lets the material stretch like a spring and spring back -- the hallmark of elasticity. Natural rubber first reached the market in the early 19th century, recovered entirely from wild Hevea brasiliensis trees of the Amazon basin (about 35% hydrocarbon in the bark latex); today roughly 1.5 million tonnes reach the market yearly, tapped as a milky latex that is coagulated into amorphous solid ru …