Titanium complexes based on aminodiol ligand for ring opening polymerization of cyclic esters

Une série de complexes à base de titane porteurs de ligands aminodiols de différentes configuration (mélange de diastéréoisomère, meso, racémique ou chiral) ont été synthétisés et caractérisés par différentes techniques spectroscopiques. Ces complexes ont ensuite été utilisés comme amorceurs pour la polymérisation par ouverture de cycles de différents monomères hétérocycliques (L/rac-lactide, caprolactone, butyrolactone et triméthylène carbonate) via un mécanisme de coordination-insertion. Tous les complexes se sont révélés efficaces pour la polymérisation des lactides que ce soit en solution à 70°C ou en masse à 130°C avec un bon contrôle. Lors de la polymérisation du rac-lactide, le complexe porteur du ligand racémique a permis d‟obtenir un polylactide partiellement heterotactique, alors que tous les autres complexes n‟ont conduit qu‟à des polymères atactiques. Tous les complexes se sont également révélés très actifs pour la polymérisation de la caprolactone aussi bien en solution qu‟en masse à 70°C avec un bon contrôle. Des études cinétiques réalisées en solution ont permis de mettre en évidence un ordre cinétique unitaire en monomère. De bonnes activités ont également été obtenues pour la polymérisation de la butyrolactone et du triméthylène carbonate. De plus, le bon contrôle de ce type de la polymérisation a permis de synthétiser des copolymères à blocs du L/rac-lactide et de caprolactone. Enfin, la copolymérisation aléatoire de ces 2 monomères a permis de mettre en évidence une réactivité inversée par rapport aux réactions d'homopolymérisation.A series of titanium isopropoxides complexes coordinated by enantiopure, racemic, meso and diastereomeric aminodiol ligands have been prepared and characterized by spectroscopic techniques. The complexes were tested as initiators for the ring opening polymerization (ROP) of cyclic esters such as L/rac-lactide, caprolactone, butyrolactone and trimethylene carbonate via coordination-insertion mechanism. In lactide polymerizations, all complexes showed significant activity both in solution at 70°C and in bulk at 130°C with a good control. The complex derived from rac-aminodiol ligand gave partially heterotactic polylactide in ROP of rac-lactide, whereas all other complexes yielded atactic polylactides. For caprolactone polymerizations, all complexes were found to be effective initiators under both solution and bulk conditions (up to 60% monomer conversion was reached within 10 min in bulk condition at 70°C), again with good control. Kinetic studies of ROP of lactides and caprolactone in solution conditions have been investigated and showed a first kinetic order in monomer. Significant activities were also observed for (ROP) of butyrolactone and trimethylene carbonate. Block copolymers of caprolactone and lactides were successfully synthesized with these catalytic systems by sequential polymerization techniques. The complexes were also tested as initiators for the production of random copolymers containing caprolactone and lactides and a reverse order of reactivity was observed between lactide and caprolactone compared to homopolymerization

Titanium complexes based on aminodiol ligand for ring opening polymerization of cyclic esters

Une série de complexes à base de titane porteurs de ligands aminodiols de différentes configuration (mélange de diastéréoisomère, meso, racémique ou chiral) ont été synthétisés et caractérisés par différentes techniques spectroscopiques. Ces complexes ont ensuite été utilisés comme amorceurs pour la polymérisation par ouverture de cycles de différents monomères hétérocycliques (L/rac-lactide, caprolactone, butyrolactone et triméthylène carbonate) via un mécanisme de coordination-insertion. Tous les complexes se sont révélés efficaces pour la polymérisation des lactides que ce soit en solution à 70°C ou en masse à 130°C avec un bon contrôle. Lors de la polymérisation du rac-lactide, le complexe porteur du ligand racémique a permis d‟obtenir un polylactide partiellement heterotactique, alors que tous les autres complexes n‟ont conduit qu‟à des polymères atactiques. Tous les complexes se sont également révélés très actifs pour la polymérisation de la caprolactone aussi bien en solution qu‟en masse à 70°C avec un bon contrôle. Des études cinétiques réalisées en solution ont permis de mettre en évidence un ordre cinétique unitaire en monomère. De bonnes activités ont également été obtenues pour la polymérisation de la butyrolactone et du triméthylène carbonate. De plus, le bon contrôle de ce type de la polymérisation a permis de synthétiser des copolymères à blocs du L/rac-lactide et de caprolactone. Enfin, la copolymérisation aléatoire de ces 2 monomères a permis de mettre en évidence une réactivité inversée par rapport aux réactions d'homopolymérisation.A series of titanium isopropoxides complexes coordinated by enantiopure, racemic, meso and diastereomeric aminodiol ligands have been prepared and characterized by spectroscopic techniques. The complexes were tested as initiators for the ring opening polymerization (ROP) of cyclic esters such as L/rac-lactide, caprolactone, butyrolactone and trimethylene carbonate via coordination-insertion mechanism. In lactide polymerizations, all complexes showed significant activity both in solution at 70°C and in bulk at 130°C with a good control. The complex derived from rac-aminodiol ligand gave partially heterotactic polylactide in ROP of rac-lactide, whereas all other complexes yielded atactic polylactides. For caprolactone polymerizations, all complexes were found to be effective initiators under both solution and bulk conditions (up to 60% monomer conversion was reached within 10 min in bulk condition at 70°C), again with good control. Kinetic studies of ROP of lactides and caprolactone in solution conditions have been investigated and showed a first kinetic order in monomer. Significant activities were also observed for (ROP) of butyrolactone and trimethylene carbonate. Block copolymers of caprolactone and lactides were successfully synthesized with these catalytic systems by sequential polymerization techniques. The complexes were also tested as initiators for the production of random copolymers containing caprolactone and lactides and a reverse order of reactivity was observed between lactide and caprolactone compared to homopolymerization

Titanium Complexes Based on Aminodiol Ligands for the Ring-Opening Polymerization of epsilon-Caprolactone, rac-beta-Butyrolactone, and Trimethylene Carbonate

Several titanium complexes based on aminodiol ligands were tested as initiators for the ring-opening polymerization (ROP) of epsilon-caprolactone under solution and bulk conditions. All complexes were found to be efficient under both conditions. For bulk polymerization at 70 degrees C, high activities were observed (113.3-156.2 g(poly) mmol(cat)(-1) h(-1)) together with controlled molar mass distribution. Kinetic studies revealed controlled polymerization, and the chain propagation was first order with respect to monomer conversion. One complex was also tested for the ROP of rac-beta-butyrolactone and the end-group analysis suggested that ring opening occurs through acyl-oxygen bond cleavage via coordination-insertion mechanism. The microstructure analysis of polymer by (13)C NMR indicates atactic polymer. Another complex was also found to be efficient initiator for the ROP of trimethylene carbonate under solution and bulk conditions. Again, end-group analysis suggests coordination- insertion mechanism

Synthetic Design of Polyester Electrolytes Guided by Hydrophobicity Calculations

Partition coefficients (LogP) help to quantify hydrophobicity, which can be used to guide the design of polymer electrolytes with targeted properties. Thus, this study combined synthetic experiments and molecular modeling to produce polyester electrolytes that solubilize lithium salts. These polyester electrolytes were derived from natural sources and polymerized with different ratios of polyols (diglycerol, glycerol, and diethylene glycol) and citric acid in the presence of lithium salts (LiTf and LiTFSI). The Fisher esterification produced homogeneous, cross-linked films with high optical transparency, whereas the lithium salts increased glass transition temperatures. The LogP values of monomers and the resulting polyesters were predicted using cheminformatics tools and indicate changing diglycerol to glycerol or diethylene glycol alters the hydrophobicity. Comparison of different molecular modeling methods with predicted LogP values demonstrate that LogP values are a reliable means of tailoring physical and chemical properties of these polymer electrolytes. Additionally, LogP values greatly benefit from being extremely less expensive from a computational standpoint as well as more convenient for calculating precursory quantitative information

Block and Random Copolymerization of epsilon-Caprolactone, L-, and rac-Lactide Using Titanium Complex Derived from Aminodiol Ligand

A series of di- and triblock copolymers [poly(L-lactide-b-epsilon-caprolactone), poly(D, L-lactide-b-epsilon-caprolactone), poly (epsilon-caprolactone-b-L-lactide), and poly(epsilon-caprolactone-b-L-lactide-b-epsilon-caprolactone)] have been synthesized successfully by sequential ring-opening polymerization of epsilon-caprolactone (epsilon-CL) and lactide (LA) either by initiating PCL block growth with living PLA chain end or vice versa using titanium complexes supported by aminodiol ligands as initiators. Poly(trimethylene carbonate-b-epsilon-caprolactone) was also prepared. A series of random copolymers with different comonomer composition were also synthesized in solution and bulk of epsilon-CL and D, L-lactide. The chemical composition and microstructure of the copolymers suggest a random distribution with short average sequence length of both the LA and epsilon-CL. Transesterification reactions played a key role in the redistribution of monomer sequence and the chain microstructures. Differential scanning calorimetry analysis of the copolymer also evidenced the random structure of the copolymer with a unique T-g