Theproductionof L-lactidefromL-lacticacidinvolvesa substantialformationofmeso-lactideas animpurity,and,uponpolymerizationwiththe industrialcatalysttin octanoate,resultsin poly(L-lacticacid)ofreducedcrystallinitydueto stereoerrorsrandomlydistributedalongthe polymerchains.We describea newapproachwherein,insteadof avoidingstereoerrorsbyremovingthemeso-lactidepriorto polymerization,thestereoerrorsin the polymerare tolerated,by crowdingthemin a stereogradientcopolymer.A zirconiumcomplexof an aminetris(phenolate)ligandis foundtoexhibitveryhighsyndioselectivityin the ringopeningpolymerizationcatalysisofmeso-lactideat roomtemper-ature,and givesrise to stereogradientcopolymersin thepolymerizationof mixturesofmeso-lactide/L-lactideinthemeltat 180°C. Relativeto thestereo-randomcopolymersobtainedwithtin octanoate,thestereo-gradientcopolymersexhibitenhancedcrystallinitiesmanifestedin lowersolubilitiesandhighermeltingtemperaturesand enthalpies.
Stereogradient Poly(Lactic Acid) from meso‐Lactide/L‐Lactide Mixtures
Venditto, VincenzoInvestigation
;
2022-01-01
Abstract
Theproductionof L-lactidefromL-lacticacidinvolvesa substantialformationofmeso-lactideas animpurity,and,uponpolymerizationwiththe industrialcatalysttin octanoate,resultsin poly(L-lacticacid)ofreducedcrystallinitydueto stereoerrorsrandomlydistributedalongthe polymerchains.We describea newapproachwherein,insteadof avoidingstereoerrorsbyremovingthemeso-lactidepriorto polymerization,thestereoerrorsin the polymerare tolerated,by crowdingthemin a stereogradientcopolymer.A zirconiumcomplexof an aminetris(phenolate)ligandis foundtoexhibitveryhighsyndioselectivityin the ringopeningpolymerizationcatalysisofmeso-lactideat roomtemper-ature,and givesrise to stereogradientcopolymersin thepolymerizationof mixturesofmeso-lactide/L-lactideinthemeltat 180°C. Relativeto thestereo-randomcopolymersobtainedwithtin octanoate,thestereo-gradientcopolymersexhibitenhancedcrystallinitiesmanifestedin lowersolubilitiesandhighermeltingtemperaturesand enthalpies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
