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Andrzej Duda - One of the best experts on this subject based on the ideXlab platform.
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Kinetics and mechanism of ε-caprolactone and l,l-lactide Polymerization coinitiated with zinc octoate or aluminum acetylacetonate: The next proofs for the general alkoxide mechanism and synthetic applications
Polymer, 2007Co-Authors: Adam Kowalski, Katarzyna Majerska, Jan Libiszowski, Andrzej Duda, Stanisław PenczekAbstract:Following our previous papers on mechanism of cyclic esters' Polymerization coinitiated by tin(II) octoate [tin(II) bis-(2-ethylhexanoate), (Sn(Oct) 2)] in the presence of either the low molar mass coinitiator (an alcohol, hydroxy acid, or H 2 O) or a macromolecule fitted with a hydroxy end group (ROH), the present work deals with 3-caprolactone (CL) and L,L-lactide (LA) Polymerizations coinitiated with zinc octoate (Zn(Oct) 2) or aluminum acetylacetonate (Al(Acac) 3). A series of kinetic measurements revealed that similarly as in the Sn(Oct) 2 coinitiated process, these Polymerizations proceed by simple monomer insertion into the .MteOR bond, reversibly formed in the reaction eMteL þ ROH # .eMteOR þ LH (where Mt ¼ Sn, Zn or Al; L ¼ Oct or Acac), taking place throughout the whole Polymerization process. MtL n itself does not play an active role in the Polymerization. Applicability of the commercially available Zn(Oct) 2 or Al(Acac) 3 for the ali-phatic polyester (10 3 M n 4 Â 10 5) synthesis is also discussed.
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Kinetics of the ring-opening Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones. Comparison of chemical and enzymatic Polymerizations
Macromolecules, 2002Co-Authors: Andrzej Duda, Stanisław Penczek, Adam Kowalski, Hiroshi Uyama, Shiro KobayashiAbstract:The kinetics of bulk Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones initiated with a zinc 2-ethylhexanoate/butyl alcohol system at 100 °C was studied and compared with that of lipase-catalyzed Polymerization. Instantaneous concentrations of the lactone monomers were determined on the basis of the relative intensities of signals in the 1H NMR spectra (500 MHz, CDCl3 as a solvent, room temperature) from the ω-methylene protons (-(CH2)x-1CH2OC(O)-) (where x ) 4, 5, 7, 10, 11, 14, and 15) in the lactone monomer and the polyester repeating units, respectively. Linearity of the semilogarithmic kinetic dependencies (ln([lactone]0/[lactone]) vs time), revealed a first order of propagation in monomer for all of the Polymerizations studied. This kinetic behavior, pointing to the constant concentration of the involved active centers and thus to the practical elimination of termination side reaction, allowed the relative Polymerization rates to be determined. The following order of Polymerization rates has been obtained: 2500:330:21:0.9:1.0:0.9:1.0 for the 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones, respectively. The order of rates of the enzymatic Polymerization, determined earlier in an independent paper, shows an inverted dependence on the ring size, namely 0.10:0.13:0.19:0.74:1.0 for the 7-, 12-, 13-, 16-, and 17-membered lactones, respectively. The resulting difference in the orders of lactone reactivities in chemical and enzymatic Polymerizations is explained in terms of a difference in factors controlling Polymerization rates in both processes. The ring strain, which decreases with increasing lactone size, is partially released in the transition state of the elementary reaction of the polyester chain growth, which eventually leads to faster propagation for more strained monomers in chemical polymeriza- tions. In enzymatic Polymerizations, the rate-determining step involves formation of the lactone-lipase complex. The latter reaction is promoted by the hydrophobicity of the lactone monomer, which is higher for the larger lactone rings.
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and 17-Membered Lactones . Comparison of Chemical and Enzymatic Polymerizations
Macromolecules, 2002Co-Authors: Andrzej Duda, Stanisław Penczek, Adam Kowalski, Hiroshi Uyama, Shiro KobayashiAbstract:The kinetics of bulk Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones initiated with a zinc 2-ethylhexanoate/butyl alcohol system at 100 °C was studied and compared with that of lipase-catalyzed Polymerization. Instantaneous concentrations of the lactone monomers were determined on the basis of the relative intensities of signals in the 1H NMR spectra (500 MHz, CDCl3 as a solvent, room temperature) from the ω-methylene protons (-(CH2)x-1CH2OC(O)-) (where x ) 4, 5, 7, 10, 11, 14, and 15) in the lactone monomer and the polyester repeating units, respectively. Linearity of the semilogarithmic kinetic dependencies (ln([lactone]0/[lactone]) vs time), revealed a first order of propagation in monomer for all of the Polymerizations studied. This kinetic behavior, pointing to the constant concentration of the involved active centers and thus to the practical elimination of termination side reaction, allowed the relative Polymerization rates to be determined. The following order of Polymerization rates has been obtained: 2500:330:21:0.9:1.0:0.9:1.0 for the 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones, respectively. The order of rates of the enzymatic Polymerization, determined earlier in an independent paper, shows an inverted dependence on the ring size, namely 0.10:0.13:0.19:0.74:1.0 for the 7-, 12-, 13-, 16-, and 17-membered lactones, respectively. The resulting difference in the orders of lactone reactivities in chemical and enzymatic Polymerizations is explained in terms of a difference in factors controlling Polymerization rates in both processes. The ring strain, which decreases with increasing lactone size, is partially released in the transition state of the elementary reaction of the polyester chain growth, which eventually leads to faster propagation for more strained monomers in chemical polymeriza- tions. In enzymatic Polymerizations, the rate-determining step involves formation of the lactone-lipase complex. The latter reaction is promoted by the hydrophobicity of the lactone monomer, which is higher for the larger lactone rings.
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Living Polymerization with reversible chain transfer and reversible deactivation: The case of cyclic esters
Macromolecular Rapid Communications, 2000Co-Authors: Stanisław Penczek, Tadeusz Biela, Andrzej DudaAbstract:Polymerization of cyclic esters at the properly chosen conditions can be treated as living Polymerization, in agreement with the tentative definition of the Nomenclature Commission of IUPAC (Macromolecular Division) requiring that no irreversible transfer or irreversible termination take place. For these processes the most kinetic or structural (end group) studies do not reveal any deviation. However, since in these Polymerizations reversible transfer to backbones of macromolecules and/or reversible deactivation take place, the molar mass distribution can be Poissonian only at certain conditions. These processes have been studied quantitatively and the corresponding rate constants were determined. Thus, the importance of these processes could be established by comparing the rate constants of propagation. In this way, Polymerizations of cyclic esters were used to illustrate the meaning and scope of the definition of "living Polymerization", a process from which irreversible transfer and deactivation are absent and in which living polymers are formed, i.e. composed of macromolecules that do not irreversibly loose their ability to grow
Shiro Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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enzymatic ring opening Polymerization and polycondensation for the green synthesis of polyesters
Polymers for Advanced Technologies, 2015Co-Authors: Shiro KobayashiAbstract:Enzyme-catalyzed polyester synthesis has been briefly reviewed with focusing on the studies achieved mainly by our group. This article describes the polyester synthesis based on the reaction mode catalyzed by enzyme with using lipase in major and protease in minor. First, ring-opening Polymerization of cyclic esters (lactones), where the macrolide monomers showed a higher polymerizability by lipase catalyst than smaller ring-sized lactones. This tendency is the reverse with the anionic and metal (Zn) catalyzed Polymerizations, which was explained from the specific mechanism of the enzymatic reaction. Chemoselective and enantioselective as well as end-functionalizing Polymerizations were mentioned. Second, condensation Polymerization (polycondensation), where two modes of reactions using oxyacid or its ester as monomer and carboxylic acid or its ester and diol as monomers were shown. Third, ring-opening addition–condensation Polymerization, where carboxylic anhydride and diol monomers were reacted involving dehydration. Finally, advantageous aspects of enzymatic polyester synthesis are described in terms of conducting green polymer chemistry. Copyright © 2015 John Wiley & Sons, Ltd.
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chemistry of 2 oxazolines a crossing of cationic ring opening Polymerization and enzymatic ring opening polyaddition
Journal of Polymer Science Part A, 2010Co-Authors: Akira Makino, Shiro KobayashiAbstract:Chemistry of 2-oxazolines is involved in the polymer synthesis fields of cationic ring-opening Polymerization (CROP) and enzymatic ring-opening polyaddition (EROPA), although both Polymerizations look like a quite different class of reaction. The key for the Polymerization to proceed is combination of the catalyst (initiator) and the design of monomers. This article describes recent developments in polymer synthesis via these two kinds of Polymerizations to afford various functional polymers having completely different structures, poly(N-acylethylenimine)s via CROP and 2-amino-2-deoxy sugar unit-containing oligo and polysaccharides via EROPA, respectively. From the viewpoint of reaction mode, an acid-catalyzed ring-opening polyaddition (ROPA) is considered to be a crossing where CROP and EROPA meet. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1251–1270, 2010
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Recent developments in lipase-catalyzed synthesis of polyesters
Macromolecular Rapid Communications, 2009Co-Authors: Shiro KobayashiAbstract:Polyester synthesis by lipase catalyst involves two major Polymerization modes: i) ring-opening Polymerization of lactones, and, ii) polycondensation. Ring-opening Polymerization includes the finding of lipase catalyst; scope of reactions; Polymerization mechanism; ring-opening Polymerization reactivity of lactones; enantio-, chemo- and regio-selective Polymerizations; and, chemoenzymatic Polymerizations. Polycondensation includes Polymerizations involving condensation reactions between carboxylic acid and alcohol functional groups to form an ester bond. In most cases, a carboxylic acid group is activated as an ester form, such as a vinyl ester. Many recently developed Polymerizations demonstrate lipase catalysis specific to enzymatic Polymerization and appear very useful. Also, since lipase-catalyzed polyester synthesis provides a good opportunity for conducting "green polymer chemistry", the importance of this is described.
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Kinetics of the ring-opening Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones. Comparison of chemical and enzymatic Polymerizations
Macromolecules, 2002Co-Authors: Andrzej Duda, Stanisław Penczek, Adam Kowalski, Hiroshi Uyama, Shiro KobayashiAbstract:The kinetics of bulk Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones initiated with a zinc 2-ethylhexanoate/butyl alcohol system at 100 °C was studied and compared with that of lipase-catalyzed Polymerization. Instantaneous concentrations of the lactone monomers were determined on the basis of the relative intensities of signals in the 1H NMR spectra (500 MHz, CDCl3 as a solvent, room temperature) from the ω-methylene protons (-(CH2)x-1CH2OC(O)-) (where x ) 4, 5, 7, 10, 11, 14, and 15) in the lactone monomer and the polyester repeating units, respectively. Linearity of the semilogarithmic kinetic dependencies (ln([lactone]0/[lactone]) vs time), revealed a first order of propagation in monomer for all of the Polymerizations studied. This kinetic behavior, pointing to the constant concentration of the involved active centers and thus to the practical elimination of termination side reaction, allowed the relative Polymerization rates to be determined. The following order of Polymerization rates has been obtained: 2500:330:21:0.9:1.0:0.9:1.0 for the 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones, respectively. The order of rates of the enzymatic Polymerization, determined earlier in an independent paper, shows an inverted dependence on the ring size, namely 0.10:0.13:0.19:0.74:1.0 for the 7-, 12-, 13-, 16-, and 17-membered lactones, respectively. The resulting difference in the orders of lactone reactivities in chemical and enzymatic Polymerizations is explained in terms of a difference in factors controlling Polymerization rates in both processes. The ring strain, which decreases with increasing lactone size, is partially released in the transition state of the elementary reaction of the polyester chain growth, which eventually leads to faster propagation for more strained monomers in chemical polymeriza- tions. In enzymatic Polymerizations, the rate-determining step involves formation of the lactone-lipase complex. The latter reaction is promoted by the hydrophobicity of the lactone monomer, which is higher for the larger lactone rings.
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and 17-Membered Lactones . Comparison of Chemical and Enzymatic Polymerizations
Macromolecules, 2002Co-Authors: Andrzej Duda, Stanisław Penczek, Adam Kowalski, Hiroshi Uyama, Shiro KobayashiAbstract:The kinetics of bulk Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones initiated with a zinc 2-ethylhexanoate/butyl alcohol system at 100 °C was studied and compared with that of lipase-catalyzed Polymerization. Instantaneous concentrations of the lactone monomers were determined on the basis of the relative intensities of signals in the 1H NMR spectra (500 MHz, CDCl3 as a solvent, room temperature) from the ω-methylene protons (-(CH2)x-1CH2OC(O)-) (where x ) 4, 5, 7, 10, 11, 14, and 15) in the lactone monomer and the polyester repeating units, respectively. Linearity of the semilogarithmic kinetic dependencies (ln([lactone]0/[lactone]) vs time), revealed a first order of propagation in monomer for all of the Polymerizations studied. This kinetic behavior, pointing to the constant concentration of the involved active centers and thus to the practical elimination of termination side reaction, allowed the relative Polymerization rates to be determined. The following order of Polymerization rates has been obtained: 2500:330:21:0.9:1.0:0.9:1.0 for the 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones, respectively. The order of rates of the enzymatic Polymerization, determined earlier in an independent paper, shows an inverted dependence on the ring size, namely 0.10:0.13:0.19:0.74:1.0 for the 7-, 12-, 13-, 16-, and 17-membered lactones, respectively. The resulting difference in the orders of lactone reactivities in chemical and enzymatic Polymerizations is explained in terms of a difference in factors controlling Polymerization rates in both processes. The ring strain, which decreases with increasing lactone size, is partially released in the transition state of the elementary reaction of the polyester chain growth, which eventually leads to faster propagation for more strained monomers in chemical polymeriza- tions. In enzymatic Polymerizations, the rate-determining step involves formation of the lactone-lipase complex. The latter reaction is promoted by the hydrophobicity of the lactone monomer, which is higher for the larger lactone rings.
Stanisław Penczek - One of the best experts on this subject based on the ideXlab platform.
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Kinetics and mechanism of ε-caprolactone and l,l-lactide Polymerization coinitiated with zinc octoate or aluminum acetylacetonate: The next proofs for the general alkoxide mechanism and synthetic applications
Polymer, 2007Co-Authors: Adam Kowalski, Katarzyna Majerska, Jan Libiszowski, Andrzej Duda, Stanisław PenczekAbstract:Following our previous papers on mechanism of cyclic esters' Polymerization coinitiated by tin(II) octoate [tin(II) bis-(2-ethylhexanoate), (Sn(Oct) 2)] in the presence of either the low molar mass coinitiator (an alcohol, hydroxy acid, or H 2 O) or a macromolecule fitted with a hydroxy end group (ROH), the present work deals with 3-caprolactone (CL) and L,L-lactide (LA) Polymerizations coinitiated with zinc octoate (Zn(Oct) 2) or aluminum acetylacetonate (Al(Acac) 3). A series of kinetic measurements revealed that similarly as in the Sn(Oct) 2 coinitiated process, these Polymerizations proceed by simple monomer insertion into the .MteOR bond, reversibly formed in the reaction eMteL þ ROH # .eMteOR þ LH (where Mt ¼ Sn, Zn or Al; L ¼ Oct or Acac), taking place throughout the whole Polymerization process. MtL n itself does not play an active role in the Polymerization. Applicability of the commercially available Zn(Oct) 2 or Al(Acac) 3 for the ali-phatic polyester (10 3 M n 4 Â 10 5) synthesis is also discussed.
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Kinetics of the ring-opening Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones. Comparison of chemical and enzymatic Polymerizations
Macromolecules, 2002Co-Authors: Andrzej Duda, Stanisław Penczek, Adam Kowalski, Hiroshi Uyama, Shiro KobayashiAbstract:The kinetics of bulk Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones initiated with a zinc 2-ethylhexanoate/butyl alcohol system at 100 °C was studied and compared with that of lipase-catalyzed Polymerization. Instantaneous concentrations of the lactone monomers were determined on the basis of the relative intensities of signals in the 1H NMR spectra (500 MHz, CDCl3 as a solvent, room temperature) from the ω-methylene protons (-(CH2)x-1CH2OC(O)-) (where x ) 4, 5, 7, 10, 11, 14, and 15) in the lactone monomer and the polyester repeating units, respectively. Linearity of the semilogarithmic kinetic dependencies (ln([lactone]0/[lactone]) vs time), revealed a first order of propagation in monomer for all of the Polymerizations studied. This kinetic behavior, pointing to the constant concentration of the involved active centers and thus to the practical elimination of termination side reaction, allowed the relative Polymerization rates to be determined. The following order of Polymerization rates has been obtained: 2500:330:21:0.9:1.0:0.9:1.0 for the 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones, respectively. The order of rates of the enzymatic Polymerization, determined earlier in an independent paper, shows an inverted dependence on the ring size, namely 0.10:0.13:0.19:0.74:1.0 for the 7-, 12-, 13-, 16-, and 17-membered lactones, respectively. The resulting difference in the orders of lactone reactivities in chemical and enzymatic Polymerizations is explained in terms of a difference in factors controlling Polymerization rates in both processes. The ring strain, which decreases with increasing lactone size, is partially released in the transition state of the elementary reaction of the polyester chain growth, which eventually leads to faster propagation for more strained monomers in chemical polymeriza- tions. In enzymatic Polymerizations, the rate-determining step involves formation of the lactone-lipase complex. The latter reaction is promoted by the hydrophobicity of the lactone monomer, which is higher for the larger lactone rings.
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and 17-Membered Lactones . Comparison of Chemical and Enzymatic Polymerizations
Macromolecules, 2002Co-Authors: Andrzej Duda, Stanisław Penczek, Adam Kowalski, Hiroshi Uyama, Shiro KobayashiAbstract:The kinetics of bulk Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones initiated with a zinc 2-ethylhexanoate/butyl alcohol system at 100 °C was studied and compared with that of lipase-catalyzed Polymerization. Instantaneous concentrations of the lactone monomers were determined on the basis of the relative intensities of signals in the 1H NMR spectra (500 MHz, CDCl3 as a solvent, room temperature) from the ω-methylene protons (-(CH2)x-1CH2OC(O)-) (where x ) 4, 5, 7, 10, 11, 14, and 15) in the lactone monomer and the polyester repeating units, respectively. Linearity of the semilogarithmic kinetic dependencies (ln([lactone]0/[lactone]) vs time), revealed a first order of propagation in monomer for all of the Polymerizations studied. This kinetic behavior, pointing to the constant concentration of the involved active centers and thus to the practical elimination of termination side reaction, allowed the relative Polymerization rates to be determined. The following order of Polymerization rates has been obtained: 2500:330:21:0.9:1.0:0.9:1.0 for the 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones, respectively. The order of rates of the enzymatic Polymerization, determined earlier in an independent paper, shows an inverted dependence on the ring size, namely 0.10:0.13:0.19:0.74:1.0 for the 7-, 12-, 13-, 16-, and 17-membered lactones, respectively. The resulting difference in the orders of lactone reactivities in chemical and enzymatic Polymerizations is explained in terms of a difference in factors controlling Polymerization rates in both processes. The ring strain, which decreases with increasing lactone size, is partially released in the transition state of the elementary reaction of the polyester chain growth, which eventually leads to faster propagation for more strained monomers in chemical polymeriza- tions. In enzymatic Polymerizations, the rate-determining step involves formation of the lactone-lipase complex. The latter reaction is promoted by the hydrophobicity of the lactone monomer, which is higher for the larger lactone rings.
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Living Polymerization with reversible chain transfer and reversible deactivation: The case of cyclic esters
Macromolecular Rapid Communications, 2000Co-Authors: Stanisław Penczek, Tadeusz Biela, Andrzej DudaAbstract:Polymerization of cyclic esters at the properly chosen conditions can be treated as living Polymerization, in agreement with the tentative definition of the Nomenclature Commission of IUPAC (Macromolecular Division) requiring that no irreversible transfer or irreversible termination take place. For these processes the most kinetic or structural (end group) studies do not reveal any deviation. However, since in these Polymerizations reversible transfer to backbones of macromolecules and/or reversible deactivation take place, the molar mass distribution can be Poissonian only at certain conditions. These processes have been studied quantitatively and the corresponding rate constants were determined. Thus, the importance of these processes could be established by comparing the rate constants of propagation. In this way, Polymerizations of cyclic esters were used to illustrate the meaning and scope of the definition of "living Polymerization", a process from which irreversible transfer and deactivation are absent and in which living polymers are formed, i.e. composed of macromolecules that do not irreversibly loose their ability to grow
Chorng-shyan Chern - One of the best experts on this subject based on the ideXlab platform.
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Effect of living polystyrene costabilizer on styrene miniemulsion Polymerization
Journal of Polymer Research, 2015Co-Authors: Shao-en Yu, Chorng-shyan ChernAbstract:RAFT miniemulsion Polymerizations of styrene with living polystyrene (PS_lc) serving as both RAFT reagent and polymer costabilizer were investigated. The miniemulsion upon aging at 25 °C showed satisfactory stability against the Ostwald Ripening process. The rate of Polymerization for RAFT miniemulsion Polymerization initiated by oil-soluble AIBN is much slower than that for the water-soluble SPS counterpart. In addition to the predominant monomer droplet nucleation, much stronger particle nucleation taking place in the continuous aqueous phase (homogeneous nucleation) for the run with AIBN was observed. It is the different extents of homogeneous nucleation that is responsible for the quite different kinetic behaviors between the RAFT miniemulsion Polymerizations initiated by different types of initiator (AIBN versus SPS). Furthermore, increasing initial molar ratio of RAFT reagent to AIBN greatly enhances the characteristics of RAFT Polymerization (i.e., better control over polymer chain growth with the progress of Polymerization).
Yves Gnanou - One of the best experts on this subject based on the ideXlab platform.
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kinetics and mechanism of controlled free radical Polymerization of styrene and n butyl acrylate in the presence of an acyclic β phosphonylated nitroxide
Journal of the American Chemical Society, 2000Co-Authors: Didier Benoit, Sandra Grimaldi, Sophie Robin, Jeanpierre Finet, And Paul Tordo, Yves GnanouAbstract:This study investigates the kinetics of free radical Polymerization of styrene and n-butyl acrylate carried out in the presence of N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)] nitroxide (DEPN). With this stable radical as chain growth moderator, it is demonstrated that the Polymerization of these two monomers exhibits a controlled character. The mechanism of Polymerization is essentially the same as that described for other “living”/controlled radical Polymerizations: the chains form a large pool of dormant species that can be reversibly activated, and only a minute fraction of them propagate at a given time. Using dilatometry and electron spin resonance (ESR), the evolution of the concentration of polymeric radicals and that of DEPN could be measured as a function of time. It appears that these DEPN-mediated Polymerizations are driven toward a pseudo-stationary state that is reached after an initial period of a few minutes. During this pseudo-stationary phase, the concentration of polymeric r...
