Ring‐Opening Copolymerization of 2,2‐Dimethyltrimethylene Carbonate and ε‐Caprolactone Using Rare Earth Aryloxides Substituted by Various Alkyl Groups

Abstract

AbstractA variety of single component rare earth aryloxides substituted by various alkyl groups [Ln(OAr)3] such as methyl, isopropyl, tert‐butyl have been surveyed in the ring‐opening copolymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and ε‐caprolactone (ε‐CL). It was worthwhile to note that activity of the catalyst varied with both the ligands' structure and the number of alkyl groups on phenyl ring. The stronger ability of electron‐donation of alkyl groups on phenyl ring, and the more numbers of alkyl groups on phenyl ring, the higher catalytic activity. The experimental results show that lanthanum tris(2,4,6‐tri‐tert‐butylphenolate) [La(OTTBP)3] exhibits highest activity in all lanthanum aryloxides. 1H NMR spectral data of copolymer obtained showed that the polymerization mechanism is in agreement with the coordination insertion mechanism.