Bulk reactions of phenolic compounds (bisphenol-A and alpha,omega-diphenol oligosulfone) or thiols (thiophenol and bis(4-mercaptophenyl)sulfide) with bisoxazoline coupling agents, namely 2,2'-(1,3-phenylene)bis-(2-oxazoline) (mbox), 2,2'-(1,4-phenylene)bis(2-oxazoline) (pybox), were carried out in the bulk at 140-240 degrees C. The reactions were followed by viscosimetry, size exclusion chromatography, and H-1- and C-13-NMR spectroscopy. The phenol/ bisoxazoline bulk reactions at 240 degrees C required the presence of sodium methoxide catalyst. Thiol and dithiol/bisoxazoline reactions were faster and did not require any catalyst. High-molar-mass polymers were obtained within 5 min at 200 degrees C while using bis(4-mercaptophenyl)sulfide (BMPS) and any of the bisoxazolines. The NMR spectra of model compounds and polymers were fully assigned, showing that the oxazoline/phenol and oxazoline/thiophenol (tph) polyaddition reactions proceed in the expected way, without any noticeable side reaction. All polymers were amorphous and displayed good thermal stability. Bisoxazolines were also used as coupling agents for the preparation of copolymers of BMPS and alpha,omega-dicarboxy polyamide-12 and for the preparation of polysulfone-polyamide-12 block copolymers. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 628-636, 2009