New polymer syntheses. 107. Aliphatic poly(thio ester)s by ring-opening polycondensation of 2-stanna-1,3-dithiacycloalkanes

We prepared 2,2-dibutyl-2-stanna-1,3-dithiacycloalkanes from dibutyltin oxi de and alpha, omega-dimercaptoalkanes. Heterocycles with five-, six-, seven -, or nine-ring members were used as bifunctional monomers for polycondensa tions with aliphatic dicarboxylic acid chlorides. These polycondensations c onducted in bulk were highly exothermic and yielded poly(thio ester)s with number average molecular weights (M-n's) in the range of 5000-30,000 Da. Th ese poly(thio ester)s proved to be rapidly crystallizing materials with mel ting temperatures in the range of 90-150 degrees C. In addition to the succ ess of the new synthetic approach, two interesting and unpredictable result s were obtained. All volatile species detectable by matrix assisted laser d esorption induced-time of flight (MALDI-TOF) mass spectrometry were cyclic oligo- and poly(thio ester)s. Second, several polyesters showed a reversibl e first-order change of the crystal modification as identified by different ial scanning calorimetry measurements and X-ray scattering with variation o f the temperature. (C) 2000 John Wiley & Sons, Inc.