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 0.1mol/L and 0.0125mol/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 0.0125mol/L. These multicyclic polythioesters were characterized by viscosity measurements, (1)H-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 alpha,omega-dibromoalkanes or tri(ethylene glycol) bistosylate all ended with gelation.