Butadiene-containing diblock/triblock

Nanocomposites Based on Partially Hydroxylated Isoprene-or Butadiene-Containing Diblock and Triblock Copolymers... 

One way to achieve compatibilization involves physical processes such as shear mixing and thermal history, which modify domain size and shape. The second way is the use of physical additives to increase attraction between molecules and phases. The third method is reactive processing, which is used to change the chemical structure of one or more of the components in the blend and thus increase their attraction to each other. Table 1.5 contains a list of compatibilizers used in the formulation of polyolefin blends. As can be seen from Table 1.5, most of the compatibilizers used in the formulation of polyolefin blends contain compounds such as maleic anhydride, acrylic and methacrylic acid, glycidyl methacrylate, and diblock and triblock copolymers involving styrene, ethylene, and butadiene. 

Commercially, procedure (b) is preferred. To obtain the desired rubbery properties in the central polybutadiene block, nonpolar hydrocarbon solvents are used to promote 1,4-addition. These solvents slow down the crossover reaction firom butadiene back to styrene in procedure (a), leading to increased polydispersity in the second polystyrene block. The linking reaction in (b) is imperfect, and commercial materials contain some diblock chains along with the desired triblock. Also keep in mind that each time material is added to a reactor, the probability of getting some terminating impurities increases. 

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