A novel hyperbranched polyester based on 2,2-bis(hydro xylmethyl)butyric acid: Synthesis and characterization

Abstract

A novel hyperbranched polyester was synthesized in bulk from 2,2-bis(hydroxymethyl)butyric acid and two different core molecules (1,1,1-tris-(hydroxylmethyl)propane and 1,3,5-tris(2-hydroxyethyl)cyanuric acid), using p-toluensolfonic acid, scandium trifluoromethanesulfonate, titanium tetrabutoxide and dibutyltin oxide as catalysts and varied reaction temperature and time. At room temperature the samples obtained appeared as glassy, slightly yellow solids, with Mn (calculated by 1H-NMR spectra) in the range 500 - 2000. The degree of branching of the polyesters was determined by 13C-NMR spectroscopy and was found in the range 0.32 - 0.53. The introduction of the monomer in various steps seems to influence slightly the degree of branching, but has no effect on the molecular weight of these polymers. The polyesters exhibited a good thermal stability, as revealed by TGA technique, and the glass transition temperature, determined by DSC, was found to depend on the molecular weight and the kind of catalyst employed.