Introduction

Ethylene, often known as ethene, is an odorless gas that can catch fire. It is one of the simplest unsaturated hydrocarbons, containing only two carbon atoms and four hydrogen atoms. A lot of ethylene is produced for many industrial uses, including the production of plastics, synthetic rubber, and chemicals. Moreover, it affects a variety of biological processes, including fruit ripening and plant growth. Due to its double bond, ethylene is extremely reactive and can undergo addition polymerization to produce polyethylene, the most commonly used plastic worldwide. Let us study its polymerization in detail.

                          Structure Of Ethylene 

Polymerization  & Types Of Polymerization 

Little molecules called monomers combine to form a bigger molecule called a polymer during the chemical reaction known as polymerization. The double or triple bonds between the atoms in the monomers must be broken to form long chains or networks.

Different types of polymerization include:

Addition Polymerization: In addition to polymerization, unsaturated monomers like ethylene are added to form a polymer chain. A catalyst, such as a complex of a transition metal, triggers it. The carbon-carbon double bond of the monomer is broken during addition polymerization, which is followed by the formation of a new single bond between the two carbons on neighboring monomers, releasing a small molecule, such as hydrogen gas.

Condensation Polymerization: Condensation polymerization includes the elimination of a tiny molecule during the polymerization process, such as water or alcohol. Materials like nylon and polyester are examples of condensation polymers. Condensation polymerization is a process that creates polymer chains out of two distinct monomers that have different functional groups, such as carboxylic acid and alcohol groups, as well as tiny molecules like water.

Polymerization On Ethylene

Ethylene can be polymerized using a variety of methods, including high-pressure free-radical polymerization, Ziegler-Natta polymerization, and metallocene polymerization.

High-pressure free-radical polymerization is the most typical method for creating polyethylene, a linear thermoplastic polymer. High pressure and a radical initiator are employed to start the reaction, ensuring that the monomers are close enough to one another for the reaction to happen. The process is quite simple and inexpensive, and it has the potential to produce polyethylene with a wide range of molecular weights and properties.

where n is the number of repeating units in the polymer chain.

Another common method for creating polyethylene is ziegler-natta polymerization. In this method, the reaction is initiated by an organo-aluminium molecule and a transition metal complex known as a Ziegler-Natta catalyst. The catalyst's capacity to control the molecular weight and structure of the polyethylene could result in a variety of polyethylene types with distinct structures resulting in several kinds of polyethylene with distinctive properties, including linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE).

where n is the number of repeating units in the polymer chain.