OBVIOUS COMPLEXITY OF THE ANIONIC-POLYMERIZATION OF MALOLACTONIC ACID-ESTERS

The anionic polymerization and copolymerization of butyl and benzyl ma lolactonates initiated with potassium acetate/dibenzo-18-crown-6 or [2 22] complex have been studied at 40 degrees C in bulk and in dichlorom ethane and tetrahydrofuran solutions. Kinetics and polymer molecular w eights were followed by SEC. In bulk and for conversion below 30%, mol ecular weights are close to those calculated for a living process then the conversion increase leads to a significant discrepancy between th eoretical and measured molecular weights. In solution, side reactions take place significantly and no evident relationship between molecular weight and initiator concentration can be established, even at low co nversion. Same situation was observed in the case of block copolymers synthesis. At last, evidence for transfer reactions has been shown by using model reactions.