Copolymers obtained by means of anionic ring‐opening polymerization. Poly(2,2‐dimethyltrimethylene carbonate)‐block‐polypivalolactone

Abstract The anionic ring‐opening polymerization of mixtures of 2,2‐dimethyltrimethylene carbonate (5,5‐dimethyl‐1,3‐dioxan‐2‐one) ( 1 ) and pivalolactone (2,2‐dimethyl‐3‐propanolide) ( 3 ) in toluene as a solvent and with potassium dihydronaphthylide as initiator, results in formation of block copolymers with yields of ca. 90%. In tetrahydrofuran as a solvent the polymer yields are ca. 65% only. In toluene, 1 polymerizes first and subsequently 3 resulting in a blocky structure of the copolymer. According to a mechanistic study, the active species is first a 1 ‐alcoholate, later a 3 ‐alcoholate and finally a 3 ‐carboxylate. The copolymers are soluble in deuterochloroform up to a mole fraction of pivalolactone of ca. 0,40. By means of 13 C NMR spectroscopy the blocky structure of the copolymers prepared in toluene was confirmed. In tetrahydrofuran as a solvent 1‐3 and 3‐1 ‐diads are formed to a significant extent. The copolymers were characterized by thermoanalytical and thermomechanical measurements.