Polybutadiene - continued microstructure

The bases of HIPS microstructure, as it is known, are laid at the stage of prepolymerization, when polymer-polymer emulsion (POO-emulsion) is obtained due to incompatibility of homopolystyrene being obtained and polybutadiene in styrene solution. Due to the fact that the particles of the discrete phase of emulsion and layers of continuous phase between them have sizes not more than tens of, the process of defusion of monomer owing to agitating is proceeding at sufficient rate. That is why the... 

The anionic polymerization of dienes is also a subject of long-term, continuous interest. Using a variety of initiators, Lewis base additives, and solvent systems, a wide range of polydiene microstructures can be prepared. Several reports have appeared regarding the relationships between polydiene microstructure, monomer concentration and chain-end concentra-tion. In general, the highest cis-1,4-microstructures for either polybutadiene or polyisoprene can be obtained at high ratios of [monomer] to... 

To improve the processibility of linear polybutadiene with its narrow molecular weight distribution, one can continuously add initiator in the course of the polymerization, vary the reaction temperature, or force long-chain branching by addition of divinyl compounds [68-74]. Addition of small amounts of ethers or tertiary amines alters the vinyl content from some 12% to more than 70% (Table 2). Bis(2-methoxy)ethyl ether and l,2-bis(dimethylamino)ethane as well as crown ethers [75,76] are particularly effective. The microstructures of the products are determinated by IR [77-87], NMR [88-99], x-ray diffraction, and other methods [100,101]. 

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