Polyolefins are mainly synthesized by supported catalysts. Typically, silica supports or MgCl2 are used for single-site catalysts like metallocenes or postmetallocenes and, as well, for Ziegler-Natta systems. The supports play a decisive role in the control of the activity of the catalysts and the product properties as the spherical shape of the supports is replicated in the product. Herein, it is demonstrated that the inorganic supports can be easily replaced by organic particles which can be obtained by emulsion polymerization. They can be surface functionalized in a high variety in such a way that they can immobilize almost all common olefin polymerization catalysts. Remarkably, Ziegler-Natta catalysts, supported on organic supports, yield PE and PP with a narrower molecular weight distribution than similar systems loaded on inorganic supports. This is attributed to the more flexible surface of an organic support which seems to allow for the formation of more uniform Ziegler-Natta catalyst species. It is also demonstrated that not only spherical particles can be produced by single-site catalysts but also for example polyolefin fibers when using supports which are obtained by electro-spinning of latex nanoparticles. Particles of an unprecedented spherical shape are accessible by using systems wherein the catalysts are immobilized in side of hollow spheres. We even succeeded to support Ziegler-Natta and metallocenes simultaneously with a spatial resolution on organic and inorganic hybrids supports. Due to the replication of the structure of the catalyst system this technique results for example in core shell structures of different types of polyolefins such as LDPE and HDPE. The role of the supports during the polymerization is monitored by video microscopy which allows an in-situ study of the polymerization process, and by confocal fluorescence microscopy which show the distribution of specially labelled supports in a product.

In-situ shape control of polyolefins products by the design of the catalyst supports

253rd National Meeting (2017)

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