Ionomers as Self Healing Polymers

Ionomers are a class of polymers which have up to 20 mol% of ionic species incorporated into the structure of the organic polymer. These ionic species create interactions or aggregates [17, 28], not present in comparable non-ionic polymers that have a profound effect upon the mechanical and physical properties of the polymer. As a result there has been much research in both academia and industry over the last 30 years [4, 22] aimed at increasing the understanding of structure–property relationships in these polymers while also exploring new commercial applications. The self healing phenomenon exhibited by ionomers is a particularly interesting property arising from their unique chemical structure and is the subject of this chapter. Despite the long-standing commercial availability of ionomers and the comprehensive structural characterisation of ionomers, there has been comparatively little research carried out (at least in the open literature) on their self healing characteristics [1, 8, 15]. This property in ionomeric systems occurs during high-energy impact or puncture where the cavity created by a projectile is immediately closed and sealed once the projectile has exited the polymer. This chapter, therefore, seeks to address the lack of information in relation to the self healing of ionomers by outlining the current understanding, research directions, and future applications for self healing ionomeric polymers. In addition to this, the chemical structure, morphology, and structure property relationships, which underpin the self healing process, will also be discussed.