ABSTRACTRecently a novel thermochro

ABSTRACT
Recently a novel thermochromic poly(lactic acid) (PLA)-composite material was presented. Depending on temperature
the incorporated anthocyanidin dye was found to be present either in its neutral or anionic anhydrobase form. A reversible
formation of PLA-dye complexes triggered by conformational changes of the polymer backbone was proposed to
explain this thermochromic effect. In order to study the influence of the dye structure on the PLA-dye complex formation
and on the thermochromic properties of the PLA-composite material a variation of the anthocyanidin dye structure
was investigated. The results indicate that a hydroxyl group in 3’-position of the anthocyanidin dye resulting in the
presence of adjacent hydroxyl groups is mandatory for the PLA-anthocyanidin dye complex formation and thus for the
occurrence of thermochromism.