Starch/Alkane Diol Materials: Unexpected Ultraporous Surfaces, Near-Isoporous Cores, and Films Moving on Water

• Published in: ACS omega 2020-11, Vol.5 (44), p.28863-28869
• Main Authors: Özeren, Hüsamettin D, Capezza, Antonio J, Gharbi, Samy, Guivier, Manon, Nilsson, Fritjof, Olsson, Richard T, Hedenqvist, Mikael S
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Chemistry; Kemi; Polymer Chemistry; Polymerkemi
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.0c04521

The aim of this study was to find alternative starch plasticizers to glycerol that yielded a less tacky material in high-moisture conditions without leading to starch crystallization. A range of glycerol films containing different potential plasticizers (linear alkane diols) were therefore produced, and it was shown that 1,3-propanediol, in combination with glycerol, was a possible solution to the problem. Several additional interesting features of the starch films were however also revealed. The larger diols, instead of showing plasticizing features, yielded a variety of unexpected structures and film properties. Films with 1,6-hexanediol and 1,7-heptanediol showed an ultraporous film surface and near-isoporous core. The most striking feature was that starch films with these two diols moved/rotated over the surface when placed on water, with no other stimulus than the interaction with water. Films with 1,8-octanediol and 1,10-decanediol did not show these features, but there was clear evidence of a structure with phase-separated crystallized diol in a starch matrix, as observed in high-resolution scanning electron microscopy (SEM) images.