Atactic polystyrene, as an amorphous material, has been known for centuries. In principle, polystyrene can occur with atactic, isotactic, and syndiotactic configurations. With the extensive studies concerning the stereoselective polymerization of olefins by Ziegler-Natta catalyst systems discovered
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in the early 1950s, the first stereoregular polystyrene, isotactic polystyrene (iPS), was obtained by Natta using the TiCl4/AlEt3 system in 1955.1 iPS is a semicrystalline polymer that has a high melting point, Tm = 240 ◦C.2 Several companies have tried to commercialize iPS, but its crystallization rate is too slow to be practical in industrial processes.