Application of functional diols derived from pentaerythritol as chain extenders in the synthesis of novel thermoplastic polyester-urethane elastomers

The success of thermoplastic elastomers is owed to the wide range of thermal, mechanical and degradation properties that enable them to be tuned to myriad applications. In large, this is achieved through the manipulation of the chemical structure of their component parts e.g. polyol, diisocyanate and diol chain extender. The permutation of diol extenders is of great interest industrially owing to their commercial availability and ease of synthesis and purification, however, the incorporation of extenders with post-polymerisation modifiable sites, specifically moieties prone to ‘click’ coupling chemistries has been relatively overlooked until recent times. Herein, the application of ‘acetal-diols’, (2-phenyl-1,3-dioxane-5,5-diyl)dimethanol (C_Ph) and (2-(norbornene)-1,3-dioxane-5,5-diyl)dimethanol (C_Nb), as extenders in the synthesis of novel thermoplastic polyurethanes (TPUs) is described. The assessment of their structure–property relationship reveals that the material properties are highly tailorable based on their urethane content. Furthermore, norbornene ‘click’ chemistries could be utilised post-polymerisation as a method of manipulating the materials’ hydrophilicity and degradability.