Use of germanium initiators in ring‐opening polymerization of L‐lactide

Abstract

Three different, new germanium initiators were used for ring‐opening polymerization of L‐lactide. Chlorobenzene and 120 °C was a usable polymerization system for solution polymerization, and the results from the polymerizations depended on the initiator structure and bulkiness around the insertion site. The average molecular weights as measured by size exclusion chromatography increased linearly with the monomer conversion, and the molecular weight dispersity was around 1.2 for initiators 1 and 2, whereas it was around 1.4 for initiator 3. The average molecular weight of poly(L‐lactide) could be controlled with all three initiators by adding different ratios of monomer and initiator. The reaction rate for the solution polymerization was, however, overall extremely slow. With an initial monomer concentration of 1 M and a monomer‐to‐initiator ratio of 50, the conversion was 93% after 161 h for the fastest initiator. In bulk polymerization, 160 °C, the conversion was 90% after 10 h. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3074–3082, 2003

Spirocycles as stable alternative of networks—polycondensations of oligoether diols with metal tetraalkoxides

“…(11)) were characterized by viscosities, 1 H NMR spectroscopy and MALDI-TOF mass spectrometry [25]. Furthermore, the Ge-PEG-spirocycles of structure 1 (prepared in our laboratory) were successfully used by Albertsson et al [26] for syntheses of A-B-A triblock copolymers derived from L-lactide. Analogous triblock-and multiblock-copolymers were prepared from Ge-PEG spirocycles and 1-CL in a future publication [27].…”

Cyclic polymers: Synthetic strategies and physical properties

“…[238][239][240][241] These spirocyclic polyesters are sensitive to hydrolysis quite analogous to the ''Bu 2 Sn polyesters'' discussed earlier. Therefore, the metal cycles may serve as SCHEME 53 Syntheses of tadpole type polyesters by starting out from sequential REP of eCL and ''eCL acrylate'' (refer preceding Scheme).…”

Role of important parameters in ring opening polymerization of polylactide

“…The melt polymerization of D,L-lactide with bis (trimethyltriazacyclohexane) praseodymium trifl ate can effi ciently be carried out at 170 ° C, is fi rst order in lactide and ½ order in Table 4 Effect of various solvents on the polymerization of D, L-lactide [11]. Wang et al [13] reported that the polymerization was carried out in bulk using creatinine as initiator and L-lactide as monomer.…”

“…Finne et al [11] reported that the new germanium initiators were used for ring opening polymerization of L-lactide. Chlorobenzene at 120 ° C was a usable polymerization system for solution polymerization.…”