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See detailMacromolecular engineering of poly(ε-caprolactone) based on macrocyclic units
Lecomte, Philippe ULg; Li, Haiying; Riva, Raphaël ULg et al

Poster (2007, May 24)

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See detailMacromolecular engineering of polylactones and polylactides. 11. Synthesis and use of alkylaluminium dialkoxides and dithiolates as promoters of hydroxy telechelic poly(epsilon-capprolactone) and alph,omega-dihydroxy triblock copolymers containing outer polyester blocks
Dubois, Philippe; Degée, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1993), 26(11), 2730-2735

Diethylaluminum dialkoxides (Et2AlOXOAlEt2, where X is either an aliphatic radical or a polymer chain) and related dithiolates have been investigated as potential initiators for the ring-opening ... [more ▼]

Diethylaluminum dialkoxides (Et2AlOXOAlEt2, where X is either an aliphatic radical or a polymer chain) and related dithiolates have been investigated as potential initiators for the ring-opening polymerization of ε-caprolactone. Hydroxy telechelic poly(ε-caprolactone) and alpha,omega-dihydroxypoly(ε-caprolactone-b-X-b-ε-caprolactone) have been accordingly prepared and characterized. A hydroxy group is selectively attached at both ends as demonstrated by IR and H-1 NMR spectroscopies and confirmed by titration of the derivatized alpha,omega-dicarboxylic acid (co)polymers. Polymerization of epsilon-caprolactone is living and yields linear polyester chains of a predictable molecular weight and of quite a narrow molecular weight distribution. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 12. Study of the depolymerizatin reactions of poly(ε-caprolactone with functional aluminum alkoxide end groups
Dubois, Philippe; Barakat, Ibrahim; Jérôme, Robert ULg et al

in Macromolecules (1993), 26(17), 4407-4412

Ring-opening polymerization of epsilon-caprolactone has been initiated with functional aluminum alkoxides in toluene at 25-degrees-C. Degradation of ''living'' polyester chains by transesterification ... [more ▼]

Ring-opening polymerization of epsilon-caprolactone has been initiated with functional aluminum alkoxides in toluene at 25-degrees-C. Degradation of ''living'' polyester chains by transesterification reactions has been studied in relation to temperature, solvent polarity, average molecular weight, and structure of the initiator, i.e., the nature of the functional group and the number of alkoxides per Al atom. Degradation products, particularly cyclic oligomers, have been isolated by supercritical fluid extraction (SFE) and characterized by GC-MS. The effect of Lewis bases on transesterification reactions has been investigated and discussed in reference to the ''coordination-insertion'' mechanism. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 14. A 13C and 27Al NMR study of the effect of γ-butyrolactone on the structure of aluminum isopropoxide in toluene
Ropson, Nathalie; Dubois, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1993), 26(24), 6378-6385

Solutions of Al isopropoxide in toluene have been investigated by C-13 and Al-27 NMR spectroscopy. Since Al(OiPr)3 is currently used as an initiator for the living polymerization of epsilon-caprolactone ... [more ▼]

Solutions of Al isopropoxide in toluene have been investigated by C-13 and Al-27 NMR spectroscopy. Since Al(OiPr)3 is currently used as an initiator for the living polymerization of epsilon-caprolactone, special attention has been paid to the effect of the monomer on the coordinative structure of Al(OiPr3) in toluene. Gamma-butyrolactone (BL) has been chosen as a nonpolymerizable model, representative of epsilon-caprolactone. The NMR spectra have been recorded at various concentrations of gamma-butyrolactone and temperatures. As a rule, Al(OiPr)3 is coordinatively aggregated in toluene in such a way that tetrameric and trimeric species are in equilibrium. Upon the addition of BL, this equilibrium is shifted toward the formation of an octahedric [Al(OiPr)3.3BL] mixed tetramer coexisting with [Al(OiPr)3]4 tetramers, the external tetrahedric Al atoms of which are coordinated with extra BL molecules. In the presence of a large excess of BL, only the mixed tetramer persists, which suggests that the single [Al(OiPr)3.3M] species would be the actual initiator for the ring-opening polymerization of cyclic monomers M, such as epsilon-caprolactone, lactides, glycolide, and cyclic anhydrides. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 17. Cryometric andviscosimetric analysis of the species active in the ring-opening polymerization of lactones, lactides, and cyclic anhydrides as initiated by aluminum triisopropoxide
Ropson, Nathalie; Dubois, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1994), 27(27), 5950-5956

Al((OPr)-Pr-i)(3), which is one of the most efficient initiators for the living ring-opening polymerization (ROP) of lactones, lactides, and cyclic anhydrides, is known to be coordinatively associated in ... [more ▼]

Al((OPr)-Pr-i)(3), which is one of the most efficient initiators for the living ring-opening polymerization (ROP) of lactones, lactides, and cyclic anhydrides, is known to be coordinatively associated in apolar solvents. In the present study, the effect of cyclic monomers on the coordinative structure of Al((OPr)-Pr-i)(3) in benzene was investigated by cryometry. gamma-Butyrolactone (gamma-BL), a nonpolymerizable lactone, was first studied as a model monomer. The cryometric Job diagram for the gamma-BL/Al((OPr)-Pr-i)(3) system in benzene established formation of a trisolvated six-coordinate [Al((OPr)-Pr-i)(3).3 gamma-BL] complex. This is in perfect agreement with the hexacoordinated Al atoms as reported by Al-27 NMR. The extension of the cryometric study to a polymerizable lactone, e.g., delta-valerolactone (delta-VL), confirmed that the single [Al((OPr)-Pr-i)(3).3M] species is the actual initiator for the ring-opening polymerization. Al-27 NMR shows that the same conclusion holds when other cyclic monomers, such as lactides and glutaric anhydride, are considered. The induction period of time that is usually observed in the ROP of lactones, lactides, and cyclic anhydrides may now be attributed to the dissociation of the Al((OPr)-Pr-i)(3) aggregates upon the addition of the cyclic monomer. Toluene solutions of living poly(epsilon-CL) and polylactide chains as initiated by Al((OPr)-Pr-i)(3) were also investigated by viscosimetry. The mean association degree ((DA)) over bar of the living chains was calculated from the intrinsic viscosity compared to the value measured for the parent hydrolyzed and purified polyester. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 18. Synthesis of star-branched aliphatic polyesters bearing various functinal end groups
Tian, Dong; Dubois, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1994), 27(15), 4134-4144

Three-arm star-branched aliphatic polyesters have been synthesized by an appropriate termination reaction of the living chains prepared by ring-opening polymerization with aluminum alkoxides. The use of ... [more ▼]

Three-arm star-branched aliphatic polyesters have been synthesized by an appropriate termination reaction of the living chains prepared by ring-opening polymerization with aluminum alkoxides. The use of functional aluminum alkoxides, Et2AlOCH2X with X = CH2CH2CH=CH2 and (CH2)10Br, has led to X functional end-capped star-branched polyesters. Trimesic acid trichloride has proved to be an efficient termination agent for the living poly(epsilon-caprolactone) [PCL] chains ended with a reactive aluminum alkoxide group. A quantitative end functionalization has been reported for bromide and 1-pentene end-capped star-branched PCL. The bromide end groups have been converted into azido end groups, which have been subsequently reduced to the expected primary amine end-capped star-branched PCL by catalytic transfer hydrogenation in DMF. In contrast to living PCL, reaction of trimesic acid chloride with the aluminum alkoxide end group of living poly(L,L)lactide [P(L,L)LA] and living poly(epsilon-caprolactone-b-(L,L)lactide) [P(CL-b-(L,L)LA] chains has produced star-branched polyesters within a very poor yield. This result is more likely due to a steric effect of the methyl group in a-position of the terminal aluminum alkoxide. This drawback has been overcome to some extent by initiating the living polymerization of (L,L)LA with primary amine end-capped star-branched PCL in the presence of triethylaluminum. Formation of a hydroxyl end-capped star-branched poly(epsilon-caprolactone-b-(L,L)lactide) diblock copolymer has accordingly been reported. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 19. Kinetics of ring-opening polymerization of epsilon-caprolactone initiated with functional aluminum alkoxides
Dubois, Philippe ULg; Ropson, Nathalie; Jérôme, Robert ULg et al

in Macromolecules (1996), 29(6), 1965-1975

End-functional aliphatic polyesters have been synthesized by ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) and lactides (LA). Polymerization initiated with any of the functional ... [more ▼]

End-functional aliphatic polyesters have been synthesized by ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) and lactides (LA). Polymerization initiated with any of the functional aluminum alkoxides of the general structure Et(3-p)Al(OCH(2)X)(p), where p = 1 and 3, obeys a living ''coordination-insertion'' mechanism, under suitable conditions (temperature, concentration, and solvent), with the formation of alpha-functional chains of a predictable molecular weight. A kinetic study has emphasized the importance of the cyclic monomer (epsilon-CL or LA) and the key role of the initiator structure: the number of functional alkoxides per aluminum and the nature of the functional group (X = CH2Br, (CH2)(2)CH=CH2, (CH2)(2)NEt(2)). Activation enthalpy and entropy have been calculated for the epsilon-CL polymerization initiated by several aluminum alkoxides at various temperatures. The effects of solvent (toluene or tetrahydrofuran) and purification of the aluminum monoalkoxides by distillation under reduced pressure have also been considered. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 20. Effect of monomer, solvent, and initiator on the ring-opening polymerization as initiated with aluminum alkoxides
Ropson, Nathalie; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Macromolecules (1995), 28(23), 7589-7598

Structure and coordinative association of the propagating species have been studied by H-1, Al-27, and C-13 NMR and viscosimetry in case of epsilon-caprolactone (E-CL) and lactides (LA) polymerization ... [more ▼]

Structure and coordinative association of the propagating species have been studied by H-1, Al-27, and C-13 NMR and viscosimetry in case of epsilon-caprolactone (E-CL) and lactides (LA) polymerization initiated by aluminum alkoxides. In toluene, aluminum triisopropoxide, a commonly used initiator, forms tetrameric (A(4)) and/or trimeric (A(3)) aggregates, which are dissociated upon the addition of the cyclic monomer. Actually, LA is responsible for the complete deaggregation of both A(3) and A(4) into single species (A(1)) trisolvated by the monomer (Al coordination number, CN = 6), whereas A(3) is selectively deaggregated by epsilon-CL. This behavior is consistent with the higher stability of A(4) compared to A(3). Whatever the monomer, three chains are initiated by the active A(1) species. When conversion of epsilon-CL is complete, the active aluminum trialkoxide sites are solvated by one (CN = 4) and more probably three (CN = 6) carbonyl groups of the attached poly-epsilon-caprolactone chains. At the complete LA conversion, only one carbonyl group of the polylactide chains is coordinated to Al (CN = 4). In THF, there is a competition between monomer and solvent for coordination to Al, which explains why polymerization is slower in THF than in toluene. In both toluene and THF, diethylaluminum monoalkoxide forms cyclic trimers that are solvated by the monomer (epsilon-CL) at least on the NMR time scale. Nevertheless, a fractional kinetic order in initiator is observed which gives credit to a fast reversible dissociation of the epsilon-CL-solvated trimers. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 21. Controlled synthesis of low molecular weight polylactide macromonomers
Barakat, Ibrahim; Dubois, Philippe ULg; Grandfils, Christian ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1996), 34(3), 497-502

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See detailMacromolecular engineering of polylactones and polylactides. 22. Copolymerization of ε-caprolactone and 1,4,8-trioxaspiro[4.6]-9-undecanone initiated by aluminum isopropoxide
Tian, Dong; Dubois, Philippe ULg; Jérôme, Robert ULg

in Macromolecules (1997), 30(9), 2575-2581

Novel biodegradable and biocompatible polyesters have been prepared by random copolymerization of ε-caprolactone (ε-CL) and 1,4,8-trioxaspiro[4.6]-9-undecanone (TOSUO) initiated by Al(OiPr)3. Copolyesters ... [more ▼]

Novel biodegradable and biocompatible polyesters have been prepared by random copolymerization of ε-caprolactone (ε-CL) and 1,4,8-trioxaspiro[4.6]-9-undecanone (TOSUO) initiated by Al(OiPr)3. Copolyesters of molecular weight (Mn) up to 104 and containing up to 90 mol % TOSUO repeating units have been prepared. The copolymer molecular weight is controlled by the molar ratio of the consumed comonomers and the initiator. The TOSUO constitutive units have been quantitatively deacetalized into ketones, which have also been efficiently reduced into hydroxyl groups without any apparent chain degradation. Therefore, poly(ε-caprolactone) (PCL) with well-defined content of ketone or hydroxyl pendent groups have been made available. The ε-CL and TOSUO comonomer units are randomly distributed within the copolymers, as assessed by the 13C-NMR sequence analysis. Indeed, the reactivity ratios (rC and rT) have been calculated from the average length of the ε-CL sequences (LC) and the TOSUO sequences (LT) and found to be 1.3 (rC) and 1.0 (rT), respectively. There is an interesting parallelism between the crystallinity and the average length of the ε-CL sequences. Copolyesters containing a molar fraction of TOSUO units smaller than 0.15 are semicrystalline, whereas the incorporation of larger amounts of TOSUO units results in amorphous copolyesters. Conversion of the ethylene acetal pendent groups into ketones and ultimately into hydroxyl pendent groups results in increasing glass transition temperature (Tg), melting temperature (Tm), and melting enthalpy (ΔHm). The thermal stability depends on the copolyester composition, since it decreases as the molar fraction of TOSUO units is increased. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 23. Synthesis and characterization of biodegradable and biocompatible homopolymers and block copolymers based on 1,4,8-trioxal [4.6] spiro-9-undecanone
Tian, Dong; Dubois, Philippe ULg; Jérôme, Robert ULg

in Macromolecules (1997), 30(7), 1947-1954

Homopolymers of 1,4,8-trioxa[4.6]spiro-9-undecanone (TOSUO) and block copolymers of TOSUO and ε-caprolactone (ε-CL) have been synthesized with aluminum isopropoxide as an initiator in toluene at 25 °C ... [more ▼]

Homopolymers of 1,4,8-trioxa[4.6]spiro-9-undecanone (TOSUO) and block copolymers of TOSUO and ε-caprolactone (ε-CL) have been synthesized with aluminum isopropoxide as an initiator in toluene at 25 °C. The homopolymerization is first order with respect to both monomer and initiator, and the end-group analysis agrees with a coordination−insertion mechanism based on the acyl-oxygen cleavage of the TOSUO ring. Living poly(ε-caprolactone) (PCL) and poly(1,4,8-trioxa[4.6]spiro-9-undecanone) (PTOSUO) chains are very efficient macroinitiators for the polymerization of TOSUO and ε-CL, respectively, with formation of block copolymers of a narrow molecular weight distribution. Size-exclusion chromatography (SEC) and 13C-NMR confirm the blocky structure of the copolymers, in agreement with DSC, which shows two glass transitions characteristic of the amorphous phase of PCL and PTOSUO, respectively. The ethylene ketal pendent groups of the PTOSUO block have been successfully converted to ketones and hydroxyl pendent groups without scission of the polyester backbone. These new materials have potential for applications in medicine, surgery, and tissue engineering. [less ▲]

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See detailMacromolecular Engineering of polylactones and polylactides. 3. Synthesis, characterization and applications of poly(ε-caprolactone) macromonomers
Dubois, Philippe; Jérôme, Robert ULg; Teyssié, Philippe

in Macromolecules (1991), 24(5), 977-981

Well-defined omega-methacryloylpoly(epsilon-caprolactone) (or PCL) macromonomers have been prepared by using an aluminum alkoxide that bears a methacrylic double bond. The initiator results from the ... [more ▼]

Well-defined omega-methacryloylpoly(epsilon-caprolactone) (or PCL) macromonomers have been prepared by using an aluminum alkoxide that bears a methacrylic double bond. The initiator results from the equimolar reaction of triethylaluminum with 2-hydroxyethyl methacrylate (HEMA). The coordination-insertion type of polymerization is living and yields exclusively linear macromonomers of a predictable molecular weight with a narrow molecular weight distribution. IR and H-1 NMR studies show that the methacryloyl group associated with the active alkoxy group of the initiator is selectively attached to one chain end. Should the living polymerization be terminated by methacryloyl chloride, and a alpha,omega-dimethacryloyl-PCL, i.e. a alpha,omega-macromonomer is obtained. PCL macromonomers and HEMA are easily copolymerized in the presence of AIBN, resulting in a hydrophilic poly(HEMA) backbone grafted with hydrophobic PCL subchains. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 4. Mechanism and kinetics of lactide homopolymerization by aluminum isopropoxide
Dubois, Philippe; Jacobs, R.; Jérôme, Robert ULg et al

in Macromolecules (1991), 24(9), 2266-2270

Aluminum isopropoxide is an effective initiator for the polymerization of lactides in toluene at 70-degrees-C. The ring-opening polymerization proceeds through a "coordination-insertion" mechanism and ... [more ▼]

Aluminum isopropoxide is an effective initiator for the polymerization of lactides in toluene at 70-degrees-C. The ring-opening polymerization proceeds through a "coordination-insertion" mechanism and selective rupture of the acyl oxygen bond of the monomer. A kinetic study has shown that the polymerization is first order in both the monomer and initiator. The polymerization is typically "living" until a molecular weight of ca. 90 000 is reached. At higher temperatures (100-degrees-C), inter- and intramolecular transesterification reactions are responsible for a limitation in the molecular weight of the growing chains. In toluene, at 70-degrees-C, each alkoxide of the aluminum isopropoxide participates in the polymerization. Any molecular weight below 90 000 can accordingly be predicted on the basis of the monomer/Al molar ratio, and the polydispersity is rather narrow (1.1-1.4). [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 5. Synthesis and characterization of diblock copolymers based on poly-ε-caprolactone and poly(L,L or D,L)lactide by aluminum alkoxides
Jacobs, C.; Dubois, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1991), 24(11), 3027-3034

Aluminum isopropoxide is known to be an effective initiator for the ring-opening polymerization of lactides (D,L and L,L) and epsilon-caprolactone (epsilon-CL). For a question of mutual reactivity, the ... [more ▼]

Aluminum isopropoxide is known to be an effective initiator for the ring-opening polymerization of lactides (D,L and L,L) and epsilon-caprolactone (epsilon-CL). For a question of mutual reactivity, the sequential polymerization of these two comonomers can only be achieved when epsilon-CL is first polymerized followed by the lactide. Formation of a large amount of homo PLA is however observed and has been attributed to a great difference in the mean degree of association of aluminum alkoxides in toluene in the presence of epsilon-CL and LA. In toluene, the mean number (n) of active sites per Al(O(i)Pr)3 molecule jumps from 1 to 3 when epsilon-CL is substituted by LA. The addition of a small amount of an alcohol, like 2-propanol, is effective in preventing the aluminum alkoxide from associating, and n is then 3 whatever the monomer used. 2-Propanol participates in the polymerization of epsilon-CL and LA as supported by a decrease in the molecular weight of the final polymer in relation to the molar amount of added alcohol. This means that the alcohol molecules are rapidly exchanged with the alkoxide groups on Al. Under such conditions, the formation of pure diblock copolymers P(epsilon-CL-b-LA) is reported. Another successful strategy for the synthesis of the diblock copolymer consists in using an Al derivative that bears only one alkoxide group to initiate the polymerization of the two cyclic esters. In this regard, a diethylaluminum alkoxide is of great value, particularly the ethoxide one. A third, conceptually similar, approach to the synthesis of P(epsilon-CL-b-LA) copolymers relates to the reaction of a performed hydroxy-terminated PCL with triethylaluminum and the use of that macroinitiator in the ring-opening polymerization of the lactide. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 7. Structural analysis of copolyesters of epsilon-caprolactone and L- of D,L-lactide initated by Al(OiPr)3
Vanhoorne, Pierre; Dubois, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1992), 25(1), 37-44

Copolymerization of mixtures of epsilon-caprolactone (epsilon-CL) and D,L- or L-lactide has been initiated by aluminum isopropoxide. On the basis of the monomer reactivity ratios and assuming that no side ... [more ▼]

Copolymerization of mixtures of epsilon-caprolactone (epsilon-CL) and D,L- or L-lactide has been initiated by aluminum isopropoxide. On the basis of the monomer reactivity ratios and assuming that no side reaction occurs, tapered copolymers should be formed particularly when D,L-lactide is the comonomer rather than L-lactide. The sequential distribution of the comonomers has been analyzed by an original method based on the quantitative measurement of the carbonyl C-13 signals. Comparison of the experimental and the theoretical distributions clearly shows that transesterification reactions occur during copolymerization through both intra- and intermolecular mechanisms. Gel permeation chromatography and differential scanning calorimetry data support that conclusion. The D,L-lactide-based copolymers have however a more blocky structure than those containing L-lactide, and they are also less sensitive to transesterification reactions. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 8. Ring-opening polymerization of ε-caprolactone initiated by primary amines and trialkylaluminum
Dubois, Philippe; Degée, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1992), 25

Whenever added with triethylaluminum, primary amines have been found to be effective initiators for epsilon-caprolactone polymerization in both toluene and THF at 40°C. The IR and NMR analysis of the ... [more ▼]

Whenever added with triethylaluminum, primary amines have been found to be effective initiators for epsilon-caprolactone polymerization in both toluene and THF at 40°C. The IR and NMR analysis of the polyester has supported a polymerization mechanism proceeding through a "coordination-insertion" pathway and the selective rupture of the acyl-oxygen bond of the monomer. The alkylaluminum activates the carbonyl group of the monomer and accordingly favors the nucleophilic addition of the amine, which is the actual initiation step. Propagation is typically a living process, and the molecular weight distribution is controlled by both AlEt3/amine molar ratio and solvent As an extension of that mechanism, diethylaluminum omega-amino alkoxide has been prepared on purpose and successfully used as an initiator for the synthesis of α,ω-dihydroxypoly(ε-caprolactone). [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. 9. Synthesis, characterization, and applications of omega-primary amine poly(ε-caprolactone)
Degée, Philippe; Dubois, Philippe; Jérôme, Robert ULg et al

in Macromolecules (1992), 25

The synthesis and use of functional diethylaluminum alkoxides (Et2AlORX) as initiators for the ring-opening polymerization of ε-caprolactone have been investigated as a possible strategy to prepare omega ... [more ▼]

The synthesis and use of functional diethylaluminum alkoxides (Et2AlORX) as initiators for the ring-opening polymerization of ε-caprolactone have been investigated as a possible strategy to prepare omega-primary amino poly(ε-caprolactone) (PCL). In a first approach, an initiator containing ethylphthalimide as the functional-RX group has been synthesized. That protected amino group has been successfully attached at the end of PCL chains. The conversion of the phthalimide end group into a primary amine has however failed, whatever the experimental conditions. In an alternative approach, an alkyl bromide has been considered as the functional group to be attached to PCL chains, via the appropriate initiator. The end functionalization was quantitative and the bromo end group converted into an azido group which was subsequently reduced to the expected primary amine. Omega-primary amino PCL has proved to be an effective macroinitiator for the ring-opening polymerization of γ-benzylglutamate N-carboxy anhydride with the formation of a poly(caprolactone-b-peptide) diblock copolymer. [less ▲]

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See detailMacromolecular engineering of polylactones and polylactides. XXV. Synthesis and characterization of bioerodible amphiphilic networks and their use as controlled drug delivery systems
Barakat, Ibrahim; Dubois, Philippe ULg; Grandfils, Christian ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1999), 37(14), 2401-2411

Well-defined ,-methacryloyl poly--caprolactone (PCL) and poly(d,l)-lactide P(D,L)LA dimacromonomers have been synthesized by living ring-opening polymerization of the parent monomers initiated by ... [more ▼]

Well-defined ,-methacryloyl poly--caprolactone (PCL) and poly(d,l)-lactide P(D,L)LA dimacromonomers have been synthesized by living ring-opening polymerization of the parent monomers initiated by diethylaluminum 2-hydroxyethylmethacrylate (Et2AlO(CH2)2OC(O)C(CH3)CH2) and terminated by reaction of the propagating Al alkoxide groups with methacryloyl chloride. These dimacromonomers have been copolymerized with a hydrophilic comonomer, i.e., 2-hydroxyethylmethacrylate, in bulk at 65°C by using benzoyl peroxide as a free-radical initiator. The swelling ability of the amphiphilic PHEMA/PCL or P(D,L)LA networks has been investigated in both aqueous and organic media. Effect of network composition and molecular weight of the dimacromonomer on the swelling kinetics and the equilibrium solvent uptake has been studied. Lipophilic dexamethasone acetate and the hydrophilic sodium phosphate counterpart have been incorporated into the amphiphilic gels and their release has been studied in relation to the gel characteristics. [less ▲]

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