Ring opening polymerisations of cyclic esters and carbonate by rare-earth LnCp3

Agarwal, Seema; Puchner, Mario

doi:10.1016/s0014-3057(02)00141-6

Cited by 43 publications

(26 citation statements)

References 21 publications

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“…Only a few reports mention the homopolymerization of carbonate using similar rare-earth initiating species, essentially of TMC, [18][19][20][21][22][23] and also of dimethyl-or ethylene-substituted carbonates. [21,[24][25][26][27][28][29][30] Poly(trimethylene carbonate (PTMC) exhibiting quite high molar-mass distributions (1.4-2.45) have been synthesized from homoleptic trivalent rareearth complexes, such as the cyclopentadienyl [LnA C H T U N G T R E N N U N G (h-C 5 H 5 ) 3 ] (Ln = Ce, Pr, Sm, Gd, Er), the guanidinate [LnA C H T U N G T R E N N U N G {R 2 NC-A C H T U N G T R E N N U N G (NR') 2 } 3 ] (R= iPr, Ph, Cy; R' = (CH 2 ) 5 , iPr, Ph; Ln = Nd, Sm, Yb), the alkoxide LnA C H T U N G T R E N N U N G (OAr) 3 (Ar = 2,6-di-tert-butyl-4-methylphenolate; Ln = Sc, La), or the halides LnX 3 (Ln = La, Nd, Sm, Gd, Dy, Yb; X = Cl, Br), at temperatures ranging from 0 to 80 8C.…”

Section: A C H T U N G T R E N N U N G (Ch 2 ) 3 Oc(o)hmentioning

confidence: 99%

Unprecedented Polymerization of Trimethylene Carbonate Initiated by a Samarium Borohydride Complex: Mechanistic Insights and Copolymerization with ε‐Caprolactone

Palard

Schappacher

Belloncle

et al. 2007

Chemistry A European J

107

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Poly(trimethylene carbonate) (PTMC) was synthesized through ring-opening polymerization by using a rare-earth borohydride initiator, [Sm(BH(4))(3)(thf)(3)]. This initiator shows a high activity to give high-molar-mass PTMCs with molar-mass distributions ranging from 1.2 to 1.4, and with a regular structure void of ether linkages. The polymers were characterized by (1)H and (13)C NMR spectroscopy, (1)H-(1)H COSY, (1)H-(13)C HMQC NMR spectroscopy, size-exclusion chromatography (SEC), viscosimetry, and MALDI-TOF MS analyses. A coordination-insertion mechanism was established based on detailed NMR characterizations, especially of the polymer chain end-functions. The monomer initially coordinates the samarium to give [Sm(BH(4))(3)(tmc)(3)], 1. The monomer then opens up through cleavage of the cyclic ester oxygen--acyl bond and inserts into the Sm--HBH(3) bond resulting in an alkoxide complex, [Sm{O(CH(2))(3)OC(O)HBH(3)}(3)], 2, or [Sm{O(CH(2))(3)OC(O)H}(3)], 2', which then propagates the polymerization of TMC to give the active polymer [Sm({O(CH(2))(3)OC(O)}(n)O(CH(2))(3)OC(O)HBH(3))(3)], 3 or [Sm(O(CH(2))(3)OC(O){O(CH(2))(3)OC(O)}(n)O(CH(2))(3)OC(O)H)(3)], 3'. Finally, acidic hydrolysis of 3 or 3' gives HO(CH(2))(3)OC(O)[O(CH(2))(3)OC(O)](n)O(CH(2))(3)OC(O)H, 4. This novel alpha-hydroxy,omega-formatetelechelic PTMC represents the first example of a formate-terminated polycarbonate. TMC and epsilon-caprolactone (CL) were copolymerized to afford both random PTMC-co-PCL and block PTMC-b-PCL copolymers that were characterized by (1)H NMR spectroscopy, SEC, and differential scanning calorimetry (DSC). The structure of the block copolymers depends on the order of addition of monomers: if CL is introduced first, dihydroxytelechelic HO-PTMC-b-PCL-OH polymers are formed, whereas introduction of TMC first or simultaneous addition of comonomers leads to hydroxyformatetelechelic HC(O)O-PTMC-b-PCL-OH analogues.

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Section: A C H T U N G T R E N N U N G (Ch 2 ) 3 Oc(o)hmentioning

confidence: 99%

Unprecedented Polymerization of Trimethylene Carbonate Initiated by a Samarium Borohydride Complex: Mechanistic Insights and Copolymerization with ε‐Caprolactone

Palard

Schappacher

Belloncle

et al. 2007

Chemistry A European J

107

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“…Such conditions induce side reactions such as transesterification and racemization, which hamper the control over the polymerization process. The scientific interest in well-defined architectures including telechelic-, block-, graft-, and star-shaped polymers has initiated major research efforts toward initiators to yield welldefined poly(lactide)s. The ROP of lactides have been investigated using various metal catalysts, including complexes of Sn, [5][6][7] Y, 8 Ln, [9][10][11][12][13] Fe, 14 Ca, 15 Ti, 16 Mg, 17 Al, [18][19][20] and Zn, [21][22][23][24][25] which generally proceeds by insertion of monomer into the metal-alkoxide bond. Some of these initiators have proved to be very attractive since they give rise to a controlled polymerization of lactide.…”

Section: Introductionmentioning

confidence: 99%

Zwitterionic ring opening polymerization of lactide by metal free catalysts: Production of cyclic polymers

Prasad

Stubbs

et al. 2011

J of Applied Polymer Sci

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Tailor made N-heterocyclic carbene (NHC) catalyst precursors namely (þ) and (À) 1-methyl-3-menthoxymethyl imidazolium chloride have been synthesized in high yield with a literature modified procedure. A reaction of catalyst precursor with potassium tert butoxide in situ generates the NHC catalyst. The zwitterionic ring opening polymerization of lactide (LA) mediated by a catalytic system composed of NHC catalyst at 25 C under argon atmosphere led to a cyclic poly(lactide) of a high molecular weight with a narrow molecular weight distribution. The cyclic poly(lactide) was characterized by NMR spectroscopy, Gel Permeation Chromatography (GPC) and Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The NHC catalysts are active for lactide polymerization in the presence of air and elevated temperatures at 55 C.

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“…Thus, physical properties should be improved by copolymerizations of lactide with other monomers in order to generate softer and tougher materials. For this purpose, cyclic carbonates are of great interest as comonomers because of the soft property of the resulting copolymers [11][12][13][14][15][16][17]. In our previous works, we studied synthesis and biodegradabilities of random copolymers of L-LA with (R)-, (S)-, or rac -1-methyltrimethylene carbonate polymerized by using a samarium initiator (C 5 Me 5 ) 2 SmMe(THF) (Sm1) [18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Sm complexes with Sn compounds for syntheses of copolymers composed of lactide and cyclic carbonates and their biodegradabilities

Nakayama

Yasuda

Yamamoto

et al. 2005

Reactive and Functional Polymers

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The comparison of organolanthanide complexes, (C 5 Me 5 ) 2 SmMe(THF) (Sm1) and [(C 5 Me 5 ) 2 Sm] 2 (PhC=C=C= CPh) (Sm2), with tin compounds, Bu 2 Sn(OMe) 2 (Sn1) and Bu 2 Sn(OCH 2 CH 2 CH 2 O) (Sn2), in the preparation of random, diblock, and triblock copolymers composed of L-lactide (L-LA) or D,L-LA and cyclic carbonates, trimethylene carbonate (TMC) or 2,2-dimethyltrimethylene carbonate (DTC) is reported. The biodegradabilities of the resulting copolymers with proteinase K and a compost were examined. The copolymerization of L-LA with cyclic carbonates by Sm1 or Sm2 afforded copolymers with relatively low melting points (<160 °C) due to the accompanying epimerization in comparison with those obtained with Sn1 or Sn2. In the degradation of the polymers with a compost, the copolymers based on D,L-LA were more degradable than those based on L-LA. On the other hand, the effect of the incorporated cyclic carbonate on its degradability was more drastic in the copolymers based on L-LA than those in the copolymers based on D,L-LA. The introduction of only a small amount of the cyclic carbonates into PLLA significantly enhanced the degradability of PLLA with a compost or proteinase K. In the enzymatic degradation of L-LA-containing polymers, the copolymerization of L-LA with TMC was also quite effective to improve the degradability of PLLA. Triblock copolymerization tends to be effective to enhance the degradability of PLLA.

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Ring opening polymerisations of cyclic esters and carbonate by rare-earth LnCp3

Cited by 43 publications

References 21 publications

Unprecedented Polymerization of Trimethylene Carbonate Initiated by a Samarium Borohydride Complex: Mechanistic Insights and Copolymerization with ε‐Caprolactone

Unprecedented Polymerization of Trimethylene Carbonate Initiated by a Samarium Borohydride Complex: Mechanistic Insights and Copolymerization with ε‐Caprolactone

Zwitterionic ring opening polymerization of lactide by metal free catalysts: Production of cyclic polymers

Comparison of Sm complexes with Sn compounds for syntheses of copolymers composed of lactide and cyclic carbonates and their biodegradabilities

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