Addition polymers are formed by a reaction in which monomer units simply add to one another. The monomers usually contain carbon–carbon double bonds. Addition polymers include polystyrene, polyethylene, polyacrylates, and methacrylates.

-Ziegler-Natta catalyst is a mixture of two compounds named as triethyl aluminium and titanium tetrachloride. This catalyst is used in the preparation of high density polyethylene and polythenes.

Ziegler- Natta catalyst contains two parts – a transition metal compound and an organoaluminum compound. It contains transition metal from group IV such as Ti, Zr, Hf etc. Organoaluminum compounds contain bonds between aluminum and carbon atoms. Examples of Ziegler-Natta catalysts include TiCl4+Et3Al and TiCl3+AlEt2Cl.

Ziegler employed a catalyst consisting of a mixture of titanium tetrachloride and an alkyl derivative of aluminum. Giulio Natta, an Italian chemist, extended the method to other olefins and developed further variations of the Ziegler catalyst based on his findings on the mechanism of the polymerization reaction.

Ziegler-Natta polymerization is a method of vinyl polymerization. It’s important because it allows one to make polymers of specific tacticity. Ziegler-Natta catalysis is especially useful, because it can make polymers that can’t be made any other way, such as linear unbranched polyethylene and isotactic polypropylene.

A Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, is a catalyst used in the synthesis of polymers of 1-alkenes (alpha-olefins).

Tacticity (from Greek τακτικός taktikos “of or relating to arrangement or order”) is the relative stereochemistry of adjacent chiral centers within a macromolecule. A tactic macromolecule in the IUPAC definition is a macromolecule in which essentially all the configurational (repeating) units are identical.

Mechanism Of Ziegler–Natta Catalyst The Ziegler-Natta catalyst involves reactions that are seen in coordination polymerisations which generally include complexes that are formed between a transition metal and the π electrons of a monomer.

Ziegler–Natta polymerization can produce an ordered syndiotactic polystyrene with the phenyl groups positioned on alternating sides of the hydrocarbon backbone. This form is highly crystalline with a Tm (melting point) of 270 °C (518 °F).

The discovery of Ziegler-Natta catalysts gave a new dimension to the world of polymers. For more than five decades remarkable progress in catalytic olefin polymerization simplified polyolefin production by eliminating deactivation, solvents, and polymer-purification steps.

Tacticity makes a big difference in polystyrene. Free radical vinyl polymerizationnormally can only produce atactic polymers. Atactic polystyrene is a hard plastic, and completely amorphous. It can’t crystallize at all. Then metallocene catalysis vinyl polymerizationwas invented, and with it, syndiotactic polystyrene became possible.

Ziegler-Natta Catalyst: History •1953 Karl Ziegler polymerizes ethene into high MW -HDPE (high density polyethylene) with catalyst based on TiCl 4 , and Et 2 AlCl as co-catalyst. • Giulio Natta, utilizes Ziegler’s catalyst to produce PP. •1963 Ziegler and Natta are awarded the Nobel Prize