No abstract

The role of solvent effects on the thermodynamics and kinetics of the coralyne self-aggregation process has been investigated in ethanol-water mixtures of different compositions. The changes in the UV/visible spectra of coralyne and FAB/LSIMS mass spectrometry agreed well with the formation of a dimer species. 1D and 2D 1H experiments have allowed one to look into the features of the self-aggregation process and to determine the equilibrium constant and the deltaH0 and deltaS0 values for the aggregate formation in 0-50% ethanol-water mixtures. The kinetics of self-aggregation has been investigated by the T-jump chemical relaxation method, and the results have been interpreted in terms of dimer formation. The dependence of the relative viscosity of coralyne solutions on the dye concentration was studied in different ethanol-water mixtures. Finally, it was found that coralyne behaves as a solvatochromic indicator which is preferentially solvated according to the sequence ethanol > ethanol-water > water. All of the results concur in elucidating the relevant role of the hydrophobic interaction process of coralyne stack formation.

Aiming at the tuning of thermo‐mechanical features by chemical cross‐linking, a biopolyester commercial blend based on poly(lactic acid) (PLA) with poly(butylene adipate‐co‐terephthalate)(PBAT) (ecovio®T2280, BASF) was processed in Brabender in the presence of dicumyl peroxide (DCP, 0–0.2 wt.‐%). The effect of DCP addition was investigated and rationalized by means of solubility tests and gel content evaluation, as well as rheological, mechanical, and molecular weight analysis of the prepared compounds. Moreover, detailed DSC and TMDSC investigations provided a deep insight into the structural modifications occurred at the macromolecular level. We found that chain branching as well as cross‐linking occurred in the samples processed in the presence of DCP, thus returning compounds having increased toughness and modulated crystalline content and thermal behavior. Noteworthy, the presence of specific, undisclosed additives, triggers the occurrence of peculiar behaviors in the ecovio® commercial blend, not previously observed in model PLA/PBAT blends of similar composition. Despite only partially soluble in chloroform, the new ecovio® DCP‐modified compounds still remained workable in the melt, thus providing a suitable, simple and economically affordable strategy to finely modulate the thermo‐mechanical properties starting from a commercially available, compostable compound.