Polymerization and copolymerization of vinyl benzoate

The polymerization and copolymerization of vinyl benzoate have been examined. The kinetics of polymerization of very carefully purified monomer are normal: the rate is proportional to the square‐root of the concentration of initiator, as well in bulk as in the presence of solvents (isopropyl benzoate and benzene). Moreover it is a reaction of first order with respect to the monomer concentration, at least in dilute solution (up to (M) = 5). The transfer constant with monomer was evaluated from rate determination and osmotic molecular weights; at 60°C. it was equal to 6·10 −4. Similarly, chain transfer constants with solvent were determined, and found to be equal at 60°C. to 1·10−4 and 7,5·10−4 for isopropyl benzoate and benzene respectively. Using 14C labelled initiator it was shown that each polymer molecule contains at low degree of conversion mainly 2–3 end groups of the initiator; this number increases up to 4–5 at high degree of conversion. By means of copolymerization experiments with vinylacetate and N‐vinyl pyrrolidone, the reactivity Q and the polarity e of the double bond of vinyl benzoate were determined; Q = 0,071 and e = −1.45. Moreover, the cross‐termination ratio Φ was evaluated in the system vinyl benzoate‐vinyl acetate; it is equal to 2.5. In the course of the purification of vinyl benzoate, some pecularities of the infra‐red spectrum of this monomer have been taken in evidence and compared to thoses of several substances of comparison.