Study of bulk chain coupling reactions. III. Reaction between bisoxazolines or bisoxazlines and carboxy-terminated oligomers

2,2′-Bis(2-oxazoline) and 2,2′-bis5,6-dihydro-(4H)-1,3-oxazine] have been used as chain coupling reagents ( CC ) and reacted in the bulk with α,ω-dicarboxy-poly(2,2′-oxydiethylene adipate) ( PS ) or with α,ω-dicarboxy-polyamide 12 ( PA ). The reactions have been followed by viscosimetry, titration of COOH groups and ¹H- and ¹³C-NMR spectroscopy. Either with the PS/CC or PA/CC systems, or with the model system dodecanoic acid ( DA )/ CC , the reactions were fast, since in most cases 80% conversion was reached after 15 min reaction. The expected DA dimer or high molar mass PA or PS polymers were obtained. No significant side reaction has been detected. The thermal stability of the resulting polymers is higher than that of starting oligomers. Due to the introduction of CC units in the chains, the crystallinity of PA/CC is slower than that of starting PA . © 1995 John Wiley & Sons, Inc.