Coordination polymerization

In 1963 German and Italian scientists were rewarded the Nobel Prize for their invention of catalysts with ability to catalyse and coordinate how vinyl monomers such as ethylene and propylene approach the active site. Thereby stereospecific polymers such as isotactic PP, shown in Figure 3, and non-branched polyethylene, HDPE, could be polymerized. Radical polymerization could only render atactic PP and branched LDPE respectively. Since then a new class of coordination catalysts called metallocene catalysts has been developed. Besides exceptional stereo-specificity they can also accomplish block-sequences of different tacticity, e.g. isotactic blocks and atactic ones that alternate and if they are long enough they will phase separate due to their different ability to crystallize.