bulk polymerization of lactides initiated by aluminium
- -
。 22. Effect of the Phenly Ring Substituent on Stereoselectivity in the Ring-Opening Polymerization of the rac-Lactide initiated by Salen Aluminum Complexes, Colloid and Polymer Science. 2015, 293, 12, 3449–3457. 。 21.
Get price
Ring-Opening Polymerization of Lactides by (Pyrazol-1 ...
The ring-opening polymerization of lactides can be cata- ... bulk of the pyrazolyl ligand in 1 ... active than the aluminium alkoxide catalyst reported by Zhong et al.27 which displays apparent rate constant of 0.902 day–1 in the L-LA polymerization reactions. 4.3. Order of Reaction With Respect to Initiator
Get price
2020
31. Synthesis of biodegradable and biorenewable polylactides initiated by aluminum complexes bearing m-xylylenediamine derivatives via the ring-opening polymerization of lactides, New J. Chem., 2019,43, 6943-6950. 。 30.
Get price
Synthesis, characterization of bulky aluminium alkoxide ...
Nov 01, 2011· The result also indicates that the polymerization is initiated through the insertion of the 2-propanoxy group from 2 into ε-CL, giving an aluminium alkoxide intermediate, which further reacts with excess lactones giving polyesters . Additionally, the "immortal" character of polymerization, which means the growing chain can exchange with ...
Get price
Single site catalysts for stereoselective ring-opening ...
Rac-3 initiated and catalyzed the polymerization of rac-LA to form a stereoblock PLA material with a P i value of 0.93 at 85% conversion of rac-LA. Notably, this excellent stereocontrol was still maintained even in a bulk polymerization. At 130 °C, the poly(rac-LA) prepared by using rac-3 has a P i value of 0.88.
Get price
DFT study of lactide ring-opening polymerizations by ...
The initiation of the ring-opening polymerization (ROP) of l-lactide, d-lactide and meso-lactide (namely, LLA, DLA and mLA, respectively) initiated by aluminium trialkoxide complex with formulae Al(OR) 3 (R = Me, i Pr and s Bu) are investigated using DFT calculations. The results show that all Al(OR) 3 >/lactide systems initiate through a coordination-insertion mechanism, involving the rate ...
Get price
- -
。 22. Effect of the Phenly Ring Substituent on Stereoselectivity in the Ring-Opening Polymerization of the rac-Lactide initiated by Salen Aluminum Complexes, Colloid and Polymer Science. 2015, 293, 12, 3449–3457. 。 21.
Get price
Bulk Ring-Opening Polymerization of Lactides Initiated by ...
Ferric alkoxides (Fe(OR)3), where R = Et, nPr, iPr, and nBu, were used as initiators for bulk ring-opening polymerization of lactides. It was showed that these ferric alkoxides were efficient initiators for the ring-opening polymerization of lactides with higher than 90% of monomer conversions polymerized at 130 °C for 36 h. Maximum molecular weights were achieved at 1/1000 of [I]/[M] mole ...
Get price
Stereo block copolymers of L- and D-lactides — University ...
T1 - Stereo block copolymers of L- and D-lactides. AU - Yui, Nobuhiko. AU - Dijkstra, Pieter J. AU - Feijen, Jan. PY - 1990. Y1 - 1990. N2 - Sequential diblock copolymers composed of L- and D-lactic acid residues were synthesized through a living ring-opening polymerization of L- and D-lactide initiated by aluminium tris(2-propanolate).
Get priceThe polymerization mechanism of lactide initiated with ...
Oct 27, 2011· Additionally, we performed lactide polymerization initiated with Zn(acac) 2, conducted in bulk at 130 °C (Table 2, row 5). The highmolecular polylactide (M n = 81 kDa – based on NMR measurement) with molecular mass dispersion M w /M n = 1.7 was obtained. However, despite the long reaction time, the final yield of reaction was relatively low ...
Get price
Ring-Opening Polymerization of Lactides by (Pyrazol-1 ...
The ring-opening polymerization of lactides can be cata- ... bulk of the pyrazolyl ligand in 1 ... active than the aluminium alkoxide catalyst reported by Zhong et al.27 which displays apparent rate constant of 0.902 day–1 in the L-LA polymerization reactions. 4.3. Order of Reaction With Respect to Initiator
Get price
Synthesis of high‐molecular‐weight poly(L‐lactide ...
The bulk polymerization of L, L ‐dilactide was studied as a function of polymerization temperature (T p), time and concentration of catalyst (tin 2‐ethylhexanoate).Poly(L ‐lactide) (PLLA), with the highest value of intrinsic viscosity ([η] = 13 dl · g −1; M̄ v ≈ 1 · 10 6) and heat of fusion (ΔH m = 64,7 J · g −1), was synthesized at a low catalyst concentration (0,015 wt ...
Get price
Ring-Opening Polymerization of L-lactide Initiated by ...
Background: The synthesis of the aliphatic polyesters obtained by the ring opening polymerization has been achieved using as initiators a large am...
Get price
Polymerization of l,l-Lactide Initiated by Aluminum ...
Bulk Ring-Opening Polymerization of Lactides Initiated by Ferric Alkoxides. Macromolecules 2005, 38 (11), 4611-4617. DOI: 10.1021/ma047545o. Haiyan Ma and, Jun Okuda. Kinetics and Mechanism of l-Lactide Polymerization by Rare Earth Metal Silylamido Complexes: Effect of Alcohol Addition.
Get price
Highly Isoselective Ring-Opening Polymerization of rac ...
Nov 16, 2020· The crystal structures of rac3 and rac5 are also identified by single crystal X-ray diffraction. In the presence of i PrOH initiator, these aluminum complexes catalyze the ring-opening polymerization (ROP) of rac-lactide (rac-LA) in a controlled manner and produce polymers with high to excellent isoselectivity (Pm up to 0.93).
Get priceBulk Ring-Opening Polymerization of Lactides Initiated by ...
Request PDF | Bulk Ring-Opening Polymerization of Lactides Initiated by Ferric Alkoxides | Ferric alkoxides (Fe(OR)3), where R = Et, nPr, iPr, and nBu, were used as initiators for bulk ring ...
Get price
Ring-Opening Polymerization of Lactides by (Pyrazol-1 ...
The ring-opening polymerization of lactides can be cata- ... bulk of the pyrazolyl ligand in 1 ... active than the aluminium alkoxide catalyst reported by Zhong et al.27 which displays apparent rate constant of 0.902 day–1 in the L-LA polymerization reactions. 4.3. Order of Reaction With Respect to Initiator
Get price
Bulk solvent-free melt ring-opening polymerization (ROP ...
Aug 01, 2011· As to the needed catalysts for the bulk solvent-free melt ROP of l-lactide, two kinds of typical catalysts have been reported: one is the metal complexes containing the characteristic initiators (alkoxide), and the ROP mechanism is the same as that in solution polymerization, and generally recognized to proceed via the reaction pathway shown in ...
Get price
Ring opening polymerisation of L-lactide initialed by ...
Polylactides were prepared by ring-opening polymerization (ROP) in bulk using as catalyst either stannous 2-ethylhexanoate at a monomer to catalyst ratio of 2000, or ferrous acetate (Fe(OAc)2) at ...
Get price
Ring‐Opening Polymerization of Lactide with Group 3 Metal ...
Sagnik K. Roymuhury, Debashis Chakraborty, Venkatachalam Ramkumar, Synthesis and characterization of group 4 metal alkoxide complexes containing imine based bis-bidentate ligands: effective catalysts for the ring opening polymerization of lactides, epoxides and polymerization of ethylene, Dalton Transactions, 10.1039/C5DT01092F, 44, 22, (10352 ...
Get price
Bulk polymerization of lactides initiated by aluminium ...
Bulk polymerization of lactides initiated by aluminium isopropoxide, 3a). ... and Robert Jérôme. Abstract. The thermal stability of poly(L-lactide) and L/D-lactide stereocopolymers polymerized in bulk with aluminium isopropoxide as initiator was investigated by thermogravimetric analysis, and time and température dependence of molecular ...
Get price
Bulk polymerization of lactides initiated by aluminium ...
Abstract. A high increase in the bulk polymerization rate of L,L-lactide and racemic D,L-lactide is observed when aluminium isopropoxide is added with an equimolar amount of a Lewis base, such as triphenylphosphine (P(Φ)3) and better 4-picoline (C6H7N).
Get price
[PDF] The mechanism of the ring-opening polymerization of ...
To obtain more insight in the ring-opening polymerization of lactones, complex formation of the initiators tetraphenyltin, stannous octoate, tin tetrachloride, aluminium bromide and triisobutylaluminium (TIBA), and the monomers L(−)-lactide, D,L-lactide and glycolide was studied by i.r.-spectroscopy. When equimolar benzene or toluene solutions of initiators and monomers were combined, only ...
Get price
Bulk Ring-Opening Polymerization of Lactides Initiated by ...
adshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A
Get price
New catalysis for fast bulk ring-opening polymerization of ...
[en] The ring-opening polymerization of lactides has been studied in bulk using either 2-ethylhexanoic acid tin(II) salt, Sn(Oct)2, or aluminum triisopropoxide, Al(OiPr)3, as the initiator over a wide range of temperature and monomer-to-initiator molar ratio, A high increase in the bulk polymerization rate has been observed when the initiator ...
Get priceBulk Ring-Opening Polymerization of Lactides Initiated by ...
May 01, 2005· adshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A
Get priceRecent advances in the synthesis of aliphatic polyesters ...
Polymerization is then initiated by any nucleophile, e.g., water or alcohol, present in the polymerization medium as impurities or as compound added on purpose. In the second mechanism, the organometallic plays the role of initiator and the polymerization proceeds through an 'insertion-coordination' mechanism (Scheme 5). Metal
Get price
Syntheses of Biodegradable Polylactides Catalyzed by ...
rac-lactides. catalyzed by aluminum hemi-Salen complexes ... The kinetics of the polymerization data indicated that the rate of polymerization initiated by complex 3 had first-order dependency on ...
Get price
DFT study of lactide ring-opening polymerizations by ...
Jul 01, 2020· The initiation of the ring-opening polymerization (ROP) of l-lactide, d-lactide and meso-lactide (namely, LLA, DLA and mLA, respectively) initiated by aluminium trialkoxide complex with formulae Al(OR) 3 (R = Me, i Pr and s Bu) are investigated using DFT calculations. The results show that all Al(OR) 3 >/lactide systems initiate through a coordination-insertion mechanism, involving the rate ...
Get priceMechanistic Insight into the Ring-Opening Polymerization ...
The reactivity and the reaction conditions of the ring-opening polymerization of ε-caprolactone (ε-CL) and L-lactide (LA) initiated by aluminum ketiminate complexes have been shown differently. Herein, we account for the observation by studying the mechanisms on the basis of density functional theory (DFT) calculations. The calculations show that the ring-opening polymerization of &epsilon ...
Get price
Bulk Ring-Opening Polymerization of Lactides Initiated by ...
Ferric alkoxides (Fe(OR)3), where R = Et, nPr, iPr, and nBu, were used as initiators for bulk ring-opening polymerization of lactides. It was showed that these ferric alkoxides were efficient ...
Get price