Joys and struggles of polyesters often melt down to crystallisation challenges

Andrew Keller was born in Budapest in 1925. A few years before, in 1920, Hermann Staudinger had come up with a statement that would revolutionise organic chemistry, change our perception about materials science, and open unlimited future perspectives for polymer science and technology. Staudinger’s statement had unintentionally shaken the very foundations of crystallography; how could macromolecules crystallise if their covalently bond atoms cannot entirely and regularly sit into crystalline lattices? Heinrich Otto Wieland could not believe it. A hundred years after Wieland’s remark, there are still plenty of researchers trying to figure out polymer crystallisation’s mechanisms. It would not have been the case without Andrew Keller’s most famous contribution to polymer science: the chain folding model (1957), a major milestone in the development of polymer physics and microstructural understanding. A hundred years after Andrew Keller’s birthday, let us celebrate the boundless opportunities offered by semi-crystalline polymers to materials science and technology, and let us do it through a tremendously promising, but also challenging, category of polymers: polyesters. This publication unfolds part of the entangled red thread relying the beginnings of polymer science to nowadays efforts to properly characterise polyesters’ complex microstructures, in memory of Andrew Keller and his precious legacy to polymer physicists investigating crystallisation.