Condensation Polymers: Their Chemical Peculiarities Offer Great Opportunities

• Published in: Progress in polymer science Vol. 89; pp. 1 - 18
• Main Author: Fakirov, S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2019
• Subjects: Additional condensation; Chemical healing; Chemically released diffusion; Trans- (exchange-) reactions; Additional condensation; Chemically released diffusion; Chemical healing; Trans- (exchange-) reactions
• ISSN: 0079-6700; 1873-1619
• DOI: 10.1016/j.progpolymsci.2018.09.003

A real case of genuine self-healing. [Display omitted] This review represents an attempt to describe and to discuss a couple of phenomena arising from the unique ability of condensation polymers to undergo post chemical interactions – additional condensation and trans- (exchange-) reactions, contrasting the rest of polymers. To them belongs the chemical healing – self-repairing of damaged polymer materials and articles via additional condensation and transreactions, which, together with the physical healing, i.e. a healing due to physical diffusion of macromolecules, are considered as the only cases of a real self-healing. Another result is the phenomenon of chemically released diffusion, the case when the mass transfer is paralleled and made possible mostly due to the exchange reactions. In this case, parts of a macromolecule leave it and are incorporated in another molecule thus making the chemical composition of macromolecules continuously changeable, particularly in polymer melts. The third phenomenon related with the specific for condensation polymers chemical interactions is the well-known and widely studied sequential reordering in condensation copolymers. Clear definitions of the basic cases including the factors determining the respective type of order are discussed. Their analysis is based on the understanding that other factors in the system determine the sequential order – the additional condensation and transreactions are a tool only for realization of one or other sequential order in condensation copolymers but by no means have they determined it. The review stresses on the fundamental importance of these reactions for polymer technology, particularly of the additional polycondensation. Large branches of polymer industry (including also recycling) are based on this process related to the increase of molecular weight of the primary synthesized polyesters and polyamides. The main target of the review is to demonstrate that these often-overlooked chemical reactions could be helpful even today in our attempts to create new or improve the existing polymer materials.