Coordination polymerization ethylene-propylene diene

The preparation of ethylene copolymers (or terpolymers) such as linear low-density polyethylenes (LLDPE), ethylene/propylene elastomers (EP), ethylene/ propylene/diene terpolymers (EPDM) is also based on these catalytic systems. Stereoregular polyisoprene and polybutadiene elastomers are also obtained by this method of polymerization the formation of 1,4-m-polydienes requires the prior double coordination of the monomer onto the growing active center ... 

Stereochemistry Coordination Polymerization. Stereoisomerism is possible in the polymerization of alkenes and 1,3-dienes. Polymerization of a monosubstituted ethylene, such as propylene, yields polymers in which every other carbon in the polymer chain is a chiral center. The substituent on each chiral center can have either of two configurations. Two ordered polymer structures are possible — isotactic (XII and syndiotactic (XIII) — where the substituent R groups on... 

Monomer. Like ethylene, propylene (propene) is a gas (Ti, = -48°C) obtained from the cracking of oil products. The monomer must be free from impurities so as to undergo polymerization by coordination catalysts indeed, impurities (polar molecules, dienes, etc.) would prevent its coordination on transition metal. Thus propylene is to be very carefully purified before its use. 

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