Monoalkylitaconates-vinylpyrrolidone copolymers. 2. Reactivity ratios and viscometric behaviour in dilute solutions

Copolymerization of mono‐n‐decyl and mono‐n‐decyl and mono‐n‐dodecyl itaconate with vinylpyrrolidone (MOI‐VP, MDI‐VP and MDoI‐VP) was carried out using AIBN as initiator. The monomer reactivity ratios were determined by the Fineman‐Ross and Kelen‐Tüdös methods. Values of r1 and r2 were found to be less than unity for MOI‐VP, MDI‐VP and MDoI‐VP, corresponding to random copolymers with some tendency to alternance. Copolymers of various compositions were studied in solution, and Mark‐Houwink‐Kuhn‐Sakurada relationships were established in ethanol for MOI‐VP and MDI‐VP copolymers, and in 1‐propanol for MDoI‐VP. The rigidity factors s̀ and the characteristic ratio C∞ were obtained from Kθ values determined by using the Stockmayer‐Fixman relation. In all the copolymers the introduction of vinylpyrrolidone units produces flexibility of the polymer chain relative to the poly(monoitaconate) homopolymers, and the solution properties of these copolymers can be described by assuming a random coil model instead of a rigid rod or wormlike model as in poly(monoitaconates).