Synthesis of poly(ε-caprolactone)-poly(L-lactide) block copolymers by melt or solution sequential copolymerization using nontoxic dibutylmagnesium as initiator

Wei, Zhiyong; Yu, Fengyun; Wang, Pei; Qu, Chen; Qi, Min

doi:10.1007/s00289-008-0964-0

Cited by 27 publications

(21 citation statements)

References 22 publications

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“…The experiment results demonstrate that LA behaves much more reactive than CL, consequently leading to a poly(LA-grad-CL) copolymer with gradient structure. 13 C NMR spectra reveal the formation of CLC linkage within the poly(LA-grad-CL), indicating the occurrence of transesterification. By calculating the average sequences lengths of copolymers, we found that the copolymer's structure can be greatly influenced by monomer composition, and the transesterification results in a more random copolymer structure.…”

Section: Discussionmentioning

confidence: 98%

“…1 H NMR and 13 C NMR spectra were recorded on a Bruker DRX-500 MHz NMR spectrometer using CDCl 3 as solvent. 13 C NMR measurements were confirmed to be quantitative with a pulse width of 30°, a spectral width of 236.8 ppm, an acquisition time of 0.7 s, and a delay of 3 s between pulses. 6 The thermogravimetric analysis(TGA) was conducted on Perkin Elmer Pyris Diamond thermogravimertic /differential thermol analyser(TG/DTA).…”

Section: Materials and Measurementsmentioning

confidence: 99%

“…[5][6][7][8][9] In this respect, the properties of PLA and PCL are complementary to each other, so the biodegradability and permeability of the copolymer synthesized from CL and LA monomers can be tailored by changing the copolymer composition, chemical structure, and molecular weight to meet the requirements of various applications. 10 Since it is of great significance to synthesize copolymers from LA and CL, a number of reports have been focused on producing both random 5,9,11,12 and block 4,9,13,14 copolymers with desirable properties.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Ring-opening polymerization of l-lactide and ε-caprolactone catalyzed by versatile tri-zinc complex: Synthesis of biodegradable polyester with gradient sequence structure

Lin

Wang

et al. 2016

European Polymer Journal

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Section: Discussionmentioning

confidence: 98%

Section: Materials and Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ring-opening polymerization of l-lactide and ε-caprolactone catalyzed by versatile tri-zinc complex: Synthesis of biodegradable polyester with gradient sequence structure

Lin

Wang

et al. 2016

European Polymer Journal

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“…Polymeric materials with adjustable degradation and mechanical properties were obtained through blending or copolymerization (10)(11)(12)(13). During the last decades, many researches have been focused on producing both random (14)(15)(16) and block (17)(18)(19)(20)(21)(22) copolymers from e-CL and LLA to provide copolymers with desirable properties.…”

Section: Introductionmentioning

confidence: 99%

Benzo-12-crown-4 modifiedN-heterocyclic carbene for organocatalyst: Synthesis, characterization and degradation of block copolymers of ϵ-caprolactone withL-lactide

Wang

Niu

Jiang

et al. 2016

Journal of Macromolecular Science, Part A

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A set of poly(L-lactide)-poly(e-caprolactone) diblock copolymers (AB) and poly(L-lactide)-poly(e-caprolactone)-poly(L-lactide) triblock copolymers (ABA) with predictable molecular weights and relatively narrow distributions were synthesized by ring-opening polymerization of successively added e-caprolactone (e-CL) and L-lactide (LLA) using 4-methyl benzo-12-crown-4 imidazol-2-ylidene as catalyst. The effects of polymerization conditions, such as reaction time, temperature, monomer/catalyst molar ratio and monomer concentration on the copolymerization have been discussed in detail. The resulting copolymers were characterized by 1 H-NMR, 13 C-NMR, IR, GPC and DSC methods which confirmed the successful synthesis of block copolymers of LLA and e-CL. Hydrolytic degradation of the polymers showed that the PLLA-PCL-PLLA copolymer exhibited faster degradation as compared with the PCL homopolymer in alkaline medium at 37 C.

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“…Figure 4 The 1 H NMR spectrum of diblock copolymer (PCL-block-PLLA) obtained by method A (Table 3, Entry 1; CDCl 3 , 400 MHz) [124] , 说明在聚合过程中酯交换副反应很少. [14,125] .…”

Section: 镁络合物催化 L-丙交酯与 ε-己内酯共聚mentioning

confidence: 99%

Non-symmetric β-Diketiminate Magnesium Complexes as Initiators for Ring-Opening Polymerization/Copolymerization of Lactide, ε-Caprolactone

布美热木·克力木¹,

Keram²

2018

Acta Chim. Sinica

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Magnesium silylamido complexes 1～7 bearing non-symmetric β-diketiminate ligands were synthesized via the reactions of corresponding proligands HL 1～7 with one equivalent of Mg[N(SiMe 3 ) 2 ] 2 at 80 ℃ in toluene. All complexes were characterized by 1 H NMR, 13 C NMR and elemental analysis. The monomeric nature of complexes 1 and 5 in the solid state was further confirmed by X-ray diffraction studies. In both complexes, the metal center is tri-coordinated by the β-diketiminate ligand and one silylamido group. The very close bond lengths of two Mg-N bonds as well as close C-N distances of the chelate ring indicate significant delocalization. The apparent deviation of the magnesium center from the ligand backbone plane suggests a certain η n -coordination nature of the ligand to the metal center. These magnesium silylamido complexes showed good catalytic activities for the ring-opening polymerization of rac-lactide under ambient conditions, and could polymerize 300 equivalents of rac-lactide to high molecular weight polymers within short time in THF. The solvent effect played a critical role during the polymerization process. All complexes showed higher catalytic activity in THF than in toluene. Taking complex 2 as an example, a monomer conversion of 96% could be achieved within 10 min in THF, whereas a conversion of 80% could only be achieved within extended polymerization time of 210 min in toluene (Table 1, Entries 6 and 9, [LA] 0 /[Mg] 0 ＝100). Upon the addition of isopropanol, the activities of magnesium silylamido complexes 1～7 increased significantly. For instance, when the polymerization runs were carried in THF in the presence of isopropanol, the reaction time could be reduced to 10～20 min even with a high molar ratio of [LA] 0 /[Mg] 0 ＝300. Moreover, the type and location of the substituent(s) on the N-aryl group of the β-diketiminate ligand exerts a significant influence on the catalytic activity of the corresponding complex toward the polymerization of rac-lactide. In the absence of excess isopropanol, the introduction of sterically demanding substituent to the ortho-position of N-aryl ring leads to a decrease of the polymerization activity; but the influence of electron-withdrawing group is different in different solvents (toluene or THF). These magnesium complexes could produce heterotactic polymers in THF (P r ＝0.64～0.80) and atactic polymers in toluene (P r ＝0.45～0.58). Magnesium complexes 1～7 also displayed high catalytic activities for the ring-opening polymerization (ROP) of ε-caprolactone, among them complexes bearing β-diketiminate ligand with bulky ortho-substituted N-aryl rings showed higher activities. Generally, the ROPs of ε-caprolactone initiated by these magnesium silylamido complexes were not well-controlled, giving moderately distributed polymers (M w /M n ＝1.37～1.67). Additionally, diblock copolymers of L-lactide and ε-caprolactone were obtained by using 2 as the initiator via both sequential feeding of two monomers (in either order) and the one-pot method. The formation of ...

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Synthesis of poly(ε-caprolactone)-poly(L-lactide) block copolymers by melt or solution sequential copolymerization using nontoxic dibutylmagnesium as initiator

Cited by 27 publications

References 22 publications

Ring-opening polymerization of l-lactide and ε-caprolactone catalyzed by versatile tri-zinc complex: Synthesis of biodegradable polyester with gradient sequence structure

Ring-opening polymerization of l-lactide and ε-caprolactone catalyzed by versatile tri-zinc complex: Synthesis of biodegradable polyester with gradient sequence structure

Benzo-12-crown-4 modifiedN-heterocyclic carbene for organocatalyst: Synthesis, characterization and degradation of block copolymers of ϵ-caprolactone withL-lactide

Non-symmetric β-Diketiminate Magnesium Complexes as Initiators for Ring-Opening Polymerization/Copolymerization of Lactide, ε-Caprolactone

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