Multicyclic Polythioesters Derived from Pentaerythritol Tetra(mercaptoacetate)

Dry pentaerythritol tetra(mercaptoacetate), PETMA, was polycondensed with double molar amounts of phthaloyl chloride, isophthaloyl chloride, tetraphthaloyl chloride, adipoyl, suberoyl, sebacoyl and 1,10‐decanedioyl chloride. Pyridine served as HCl‐acceptor and catalyst. The concentration of PETMA was varied between 0.1 mol/L and 0.0125 mol/L. With the aromatic dicarboxylic acid, dichlorides gelation occurred in all experiments. With aliphatic dicarboxylic acid dichlorides (ADADs), soluble multicyclic polythioesters were obtained at concentrations of 0.025 or 0.0125 mol/L. These multicyclic polythioesters were characterized by viscosity measurements,¹H‐NMR spectroscopy and MALDI‐TOF mass spectrometry. A few experiments with pentaerythritol tetra(mercaptopropionate) showed a lower cyclization tendency relative to PETMA. Polycondensations of PETMA with α,ω‐dibromoalkanes or tri(ethylene glycol) bistosylate all ended with gelation.