Solid Phase Ring-opening Polymerization of Macrocyclic S-Aryl Thioesters Containing Terephthaloyl Structure

Abstract

We have studied synthesis and solid-state ring-opening polymerization of macrocyclic S-aryl thioesters, dimer p-BBDT-2, trimer p-BBDT-3, and tetramer p-BBDT-4 containing terephthaloyl structure. The targeted p-BBDT-2, p-BBDT-3, and p-BBDT-4 were prepared by the reaction of terephthaloyl chloride (TPC) with 4- tert-butyl-1,2-benzenedithiol (BBDT) using NaOH under phase transfer conditions. The macrocyclic trimer p-BBDT-3 was obtained preferentially in 81% yield by a reaction at a concentration of 1.0 mol 1-1 in a mixture of aqueous NaOH and chloroform. The structures of the prepared macrocyclic S-aryl thioesters were well identified by IR, 1H NMR, 13C NMR spectroscopies, MALDI-TOF MS, and elemental analysis. The solubility and thermal properties of p-BBDT-2, p-BBDT-3, and p-BBDT-4 were characterized. It was found that the ring-opening polymerization of p-BBDT-2, p-BBDT-3, and p-BBDT-4 without catalysts occurred in the solid state, and the corresponding poly( S-aryl thioester)s with moderate molecular weights were obtained. The behaviors of the polymerization of p-BBDT-3 and catalytic effect of potassium halides/dibenzo-18-crown-6 complexes were examined. It was also found that the poly( S-aryl ester) obtained by a solid-state polymerization had good thermal properties.