One of the most exciting developments in the areas of catalysis, organometallic chemistry, and polymer science in recent years has been the intense exploration and commercialization of new polymerization technologies based on single-site and metallocene coordination olefin polymerization catalysts.1 The vast number of specifically designed/synthesized transition metal complexes (catalyst precursors) and main-group organometallic compounds (cocatalysts) allows unprecedented control over polymer microstructure, the generation of new polymer architectures, and the development of new polymerization reactions. Commercialization of new generations of single-site and metallocene catalyst-based technologies has provided the multibillion pound per year polyolefins industry with the ability to deliver a wide range of new and innovative olefin-based polymers having improved properties.2-4 The intense industrial activity in the field and the challenges to our basic understanding that have come to light have in turn 1391 Chem. Rev. 2000, 100, 1391−1434

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Cocatalysts for Metal-Catalyzed Olefin Polymerization: Activators, Activation Processes, and Structure−Activity Relationships

Selectivity in propene polymerization with metallocene catalysts.

2.2.1. Polyisocyanates 6117 2.2.2. Polysilanes 6118 2.2.3. Polyacetylenes 6120 2.3. Foldamer-Based Helical Polymers 6124 2.3.1. Click Polymerization 6126 2.3.2. Ring-Closing Reaction 6126 2.4. Other Types of Helical Polymers 6127 2.4.1. π-Conjugated Helical Polymers 6127 2.4.2. Metallosupramolecular Helical Polymers 6128 2.5. Induced Helical Polymers 6130 2.5.1. Induced Helical Polyacetylenes 6130 2.5.2. Other Induced Helical Polymers and Oligomers 6132

Helical polymers: synthesis, structures, and functions

Living ring-opening metathesis polymerization

Synthetic helical polymers: conformation and function.

Publisher Summary This chapter discusses crystalline high polymers of α-olefins. The linear crystalline polymers of α-olefins are synthesized and the chapter also discusses the properties of crystalline polypropylene, poly-α-butylene, and polystyrene. Depending on the structure of the catalyst, different amounts, ranging from 0 to 100%, of the polymerization products are crystallizable and can be separated easily from the much more soluble noncrystalline polymers by solvent extraction. The new crystalline poly hydrocarbons have higher melting point, higher density, and lower solubility in organic solvents than the corresponding amorphous polyhydrocarbons having intrinsic viscosity of the same order of magnitude. The infrared spectra of crystalline polypropylene, of melted samples of the same polymer and of the amorphous polypropylene, show between 2 and 7.5 μ, the high adsorption regions characteristic of hydrocarbons.

CRYSTALLINE HIGH POLYMERS OF α-OLEFINS

Publisher Summary This chapter discusses the nature of some soluble catalysts for low-pressure ethylene polymerization. Soluble catalysts for the low-pressure ethylene polymerization have been found which are less active than the best heterogeneous catalysts, but which are much more suitable for the basic research on chemical nature of the catalysts. The soluble catalytic system obtained from organo-aluminium compounds and Ti compounds in which the Ti atom is bound to two cyclopentadienyl groups. A crystallizable bimetallic complex has been synthesized which is a catalyst for the polymerization of ethylene. It can be concluded that the Ziegler-type polymerization catalysts are complexes containing organometallic bonds and more than one metal atom.

The nature of some soluble catalysts for low pressure ethylene polymerization

Complessi cristallizzabili contenenti titanio e alluminio cataliticamente attivi nella polimerizzazione dell'etilene

Publisher Summary This chapter discusses a crystallizable organometallic complex containing titanium and aluminium. A crystallizable compound containing titanium, aluminium and organometallic bonds, was isolated which causes the polymerization of ethylene. By treating the blue product with 2-ethylhexanol, ethane is evolved; a quantitative gas volumetric determination shows that two moles of ethane are evolved per mole of compound. By treating the product with anhydrous hydrochloric acid in ether solution, bis-(cyclopentadienyl)-titanium dichloride is formed in almost quantitative yield. By polymerizing ethylene in heptane solution in the presence of 0.6 g of the Ti-Al complex at 40 atm and 95° after a reaction time of 20 hour, 84 g of white polymer has been obtained, which has been fractionated by boiling solvent extraction.

Piero Pino

Papers

CRYSTALLINE HIGH POLYMERS OF α-OLEFINS

The nature of some soluble catalysts for low pressure ethylene polymerization

Complessi cristallizzabili contenenti titanio e alluminio cataliticamente attivi nella polimerizzazione dell'etilene

A crystallizable organometallic complex containing titanium and aluminum

CRYSTALLINE HIGH POLYMERS OF α-OLEFINS