Lactic acid copolyesters with carboxyl derivatives of p-tert-butylthiacalix[4]arene: synthesis and effect of macrocycle conformation on the physicochemical properties

Abstract

An approach to p-tert-butylthiacalix[4]arene derivatives functionalized with lactic acid fragments in three conformations (cone, partial cone, 1,3-alternate) was developed. The use of tetraglyme as a solvent and magnesium sulfate with p-toluenesulfonic acid as co-condensation catalysts made it possible to obtain the desired products without admixtures of oligolactic acid. The structure of the synthesized macrocycles was characterized by a complex of physico-chemical methods. The thermal properties of the synthesized lactic acid copolyesters were studied by simultaneous thermogravimetry and differential scanning calorimetry analysis. Significant effect of the p-tert-butylthiacalix[4]arene platform on the thermal stability of the obtained products was demonstrated. Nanoscale particles of the synthesized macrocycles with a low polydispersity index were obtained using nanoprecipitation from methanol or acetone into a buffer solution.