Polycaprolactone

Advantages and disadvantages of different methods used in synthesis of polycaprolactone

Polycaprolactone- It is an aliphatic polyester with a linear structure, a biodegradable polymer. [pic 1]

This material fits the definitions with complete confidence:

Eco-friendly;

Multifunctional;

Comfortable;

Economical.

Options where this polymer is successfully used

Surgical suture material [biodegradable]

Medical thermoplastic splints and bandage:

Interior design.

Synthesis of polycaprolactone

Synthesized from ε-caprolactone by heating and using catalysts[pic 2]

Depending on the catalyst, there are four main mechanisms of cycle polymerization: anionic, cationic, monomer-activation and coordination-insertion.

The anionic mechanism implies the formation of anionic complexes that open. The main disadvantage of this method is significant intramolecular transesterification at later stages of polymerization. This leads to a decrease in the molecular weight of the polymer, stopping polymerization or producing cyclic polymers.

The cationic mechanism consists in the formation of a cationic radical, which subsequently attacks the oxygen of the carboxyl group of the monomer through the reaction of a nucleophilic bimolecular substitution.

Monomer activation involves the activation of a monomer molecule with the help of a catalyst and the subsequent addition of the activated monomer to the end of the polymer chain

Coordination-insertion is the most common type of cycle polymerization; in fact, it is a special case of anionic mechanism. The process involves the orientation of the monomer and the catalyst with the subsequent formation of a metal-oxygen bond between the catalyst and the monomer molecule. Further growth of the chain occurs due to the addition of a C-O bond to the metal.

During the polymerization process, due to the presence of a catalyst a transesterification reaction may occur, which occurs as intermolecular and intramolecular. Typically, these reactions begin at late stages of the polymerization reaction under high temperature conditions. This leads to an increase in polydispersity and loss of control over the process.

The final molecular weight of the polymer, molecular weight distribution and the presence of functional groups can vary depending on the polymerization mechanism.