Hyperbranched Poly(Ether Amide)s via Nucleophilic Ring Opening Reaction of Oxazolines

Abstract

The nucleophilic ring opening addition reaction of phenol groups towards oxazoline units has been used for the preparation of hyperbranched poly(ether amide)s. For this the AB2 monomer 2-(3,5-bishydroxyphenyl)-1,3-oxazoline was synthesized and converted in a highly branched polymer in bulk or solution at temperatures above 190°C. The resulting hyperbranched polymers exhibit a degree of branching of 50%, as verified by high-resolution NMR spectroscopy, and are highly soluble in polar organic solvents, for example DMF and DMAc, with low solution viscosity. Their glass transition temperatures are in the region of 170°C and degradation does not start below 300°C. Melt rheology measurements revealed a predominantly elastic behaviour with a relatively high viscosity at low frequency. A lower melt viscosity was achieved by end group modification. Hyperbranched poly(ether amide)s with phenolic and acetate end groups are fully miscible with linear polyamide 6. When a small amount of the hyperbranched material is added to the PA6 matrix a significant reduction of the melt viscosity could be achieved without changing the mechanical properties of the matrix polymer.