Polybutadiene Polyols by Radical Polymerisation of Butadiene

It is well known that radical polymerisation is a chain reaction characterised by initiation, propagation and termination reactions [1]  

It is very clear that if the initiator has hydroxyl groups, and if the termination takes place exclusively by recombination then a polymeric diol is obtained [2, 3], which is ideal for polyurethane. If the termination takes place by disproportionation, only monofunctional compounds are obtained, which cannot be used in PU. The vinylic and dienic monomers used in practice have various termination mechanisms. Some monomers give only recombination reactions, such as styrene, acrylates (methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethyl hexyl acrylate), acrylonitrile and butadiene. Other monomers give both mechanisms of termination, around 65-75% disproportionation and 25-35% recombination, such as methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate etc.), substituted styrenes and other monomers [2, 3, 4]. 

It is very clear that only the first group of monomers, which lead to termination by recombination, can be used for synthesis of hydroxy-telechelic polymers which are useful in polyurethane fabrication and from the second group of monomers it is impossible to obtain oligo-polyols useful in PU. 

Hydrogen peroxide is decomposed to very reactive hydroxyl radicals either thermally or by a redox system [8]  

In the presence of alcohols (used frequently as solvents), the very reactive hydroxyl radical gives transfer reactions (reactions 9.1 and 9.2) [2, 3]. 

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Synthesis of Polybutadiene Polyols by Radical Polymerisation of Butadiene [2, 3, 5-7, 9-15]... 

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