Macromolecular Chemistry and Physics · 1997 · 56 citations · 17 references
Natural SciencesChemical EngineeringChemistryPolymer ChemistryPolymer EngineeringPolymer MaterialsPolymerization ChemistryPolymerization ProcessesPolymerization Temperature EffectsHigh-temperature PolymerizationOptimum TemperaturePoly(lactic Acid)Poly(lactic-co-glycolic Acid)Polymer InitiatorsPolymerization MechanismsTemperature OptimumViscosity Effects On Polymerization
Abstract Commercial FeCl 2 and Fe(II) glycolate, Fe(II) L ‐lactate or Fe(II) L ‐mandelate were used as initiators for the polymerization of L ‐lactide. All polymerizations were conducted in bulk at 150°C, because no conversion was observed in bulk at 120°C. The Fe(II) lactate was found to be more reactive than FeCl 2 , and it yielded slightly higher molecular weights than all other initiators. Under the optimum conditions, viscosity average molecular weights ( M̄ v ) around 50 000 and yields above 90% were obtained. However, slight racemization (2–5%) of the isolated poly(L‐lactide) was also observed under most circumstances. Characterization of unreacted monomer proved that the racemization mainly involves the monomeric lactide due to its higher CH acidity.
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Configurational structures of lactic acid stereocopolymers as determined by 13C{1H} n.m.r.
F. Chabot, Michel Vert, Stella Chapelle et al. · Polymer · 1983 · 233 citations
H. R. Kricheldorf, Àngels Serra · Polymer Bulletin · 1985 · 187 citations