Abstract:
The polymerization of butadiene, initiated by the complexes of n-butyl lithium and tetramethyl
ethylene diamine, has been studied in the range 230-280 K by dilatometry. Initial rates of polymerization were second order in monomer, and first in both amine and butyl lithium concentrations.
Maximum rates were observed at molar ratios of lithium alkyl/amine below' I /2. Rates of polymerization decreased with conversion, consistent with first-order dependence on unconverted monomer.
Molecular weights of the polymers increased with conversion, and at ratios below' 1 /2 in alkyl/amine
compared exactly with moles of monomer consumer per mole of butyl lithium initially present. The
micro-structure of the polymers varied with polymerization temperatures between 70-90 % of 1,2
addition product. All the polymers had narrow molecular weight distributions independent of the
final degree of conversion.
It was concluded that the polymerization of butadiene occurred by a “ living” anionic addition
mechanism, initiated by the 1 /2 amine complex. The nature of the active polymerizing species was
confirmed by a molecular weight study of the complexes present at various molar ratios, and their
concentration dependence.
