Chemical modification of a polymer – Wikipedia

The Chemical modification of polymers consists of a modification of the nature of the reactive groups carried by a polymer chain. The modification can take place on functional groups or unsaturations at the end of the chain, on the side chains or at the level of the main skeleton of the polymers.

The main goals of the chemical modifications of the polymers are:

• Create polymers with specific properties;
• Make polymers whose monomers do not exist or are not very stable.

The chemical modification of polymers can take place with an increase in the molar mass of the polymer (copolymerization, etc.), with decrease in this mass (depolymerization, degradation of polymers, chain cut, etc. ) or without variation of this mass (some cyclists, some reticlations, etc. ).

The main process of chemical modifications of polymers are:

• the cyclisation ^{[ first ]} : cyclization of polymers is a chemical reaction that leads to:
  • The formation of cycles in polymers. The cyclization reaction takes place when there are two neighboring units which can react together to form cycles. Examples:
  • The transformation of all the polymer into a single cycle. The cyclization reaction takes place when there are two units at the end of the chain which can react together to form a cycle. Example: cyclization of polydimethylsiloxane;
• the functionalization ^{[ 2 ]} : the functionalization of polymers is the introduction of chemical groups into polymers to create a product with specific properties;
• the copolymerization which takes place by grafting ( grafting onto ) or by radiation ( grafting from );
• the retication ;
• the depolymerization : conversion process of a polymer into a monomer or a mixture of monomers;
• the chain cut : chemical reaction leading to the break of skeleton links ^{[ 3 ]} .

Chemical changes in polymers can take place using post-modern reagents or not. These reagents can be:

Modified polymers can be natural or synthetic.

Without post-modern reagent [ modifier | Modifier and code ]

The chemical modification of polymers can take place thanks to an increase in temperature or the presence of a catalyst.

Modification of synthetic polymers [ modifier | Modifier and code ]

• Cyclisation du polyacrylonitrile.
• Cyclization of polyalcadiens with conjugated dines.

Monofunctional post-text reignings [ modifier | Modifier and code ]

The formed polymer does not change architecture.

Modification of natural polymers [ modifier | Modifier and code ]

Modification of synthetic polymers [ modifier | Modifier and code ]

• The chemical modification of the poly (vinyl alcohol) can give:

Polyfunctional post-text reagents [ modifier | Modifier and code ]

This type of molecule will cause retication by connecting the reactive groups between them. We then talk about post-retirement .

Modification of natural polymers [ modifier | Modifier and code ]

Modification of synthetic polymers [ modifier | Modifier and code ]