Kinetics of Anionic Polymerization of ε-Caprolactone (εCL). Propagation of Poly-ε=CL-K<sup>+</sup>Ion Pairs

Sosnowski, S.; Slomkowski, S.; Penczek, Stanisław

doi:10.1080/00222338308060806

Cited by 33 publications

(4 citation statements)

References 9 publications

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“…Alkali metal alkoxide and amide bases have been routinely applied as initiators in the ring-opening polymerization (ROP) of epoxides, − thiolactones, , cyclic esters, − and cyclic carbonates. − These conditions typically involved either long reaction times , or lead to uncontrolled reactions . For example, Sipos, et al demonstrated that polymerization of l -lactide (L-LA) using potassium tert -butoxide (KO t Bu) is characterized by poor initiator efficiency, leading to broad dispersity ( D̵ > 1.4) and long reaction times to reach high conversion (83% at 22 h).…”

Section: Introductionmentioning

confidence: 99%

Ultrafast and Controlled Ring-Opening Polymerization with Sterically Hindered Strong Bases

et al. 2020

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The controlled anionic ring-opening polymerization of lactones and siloxanes is carried out in continuous-flow reactors. Anionic ring-opening polymerization of cyclic esters with strong, soluble bases such as potassium tert-butoxide (KOtBu) is typically performed as batch reactions, leading to broad dispersity and poor control over the molecular weight (M n) mainly because of transesterification reactions. Although reactions with strong bases give rise to “uncontrolled” polymerizations, a variety of transition metal-based and organocatalysts have been developed with the goal of reliably controlling the dispersity and M n. Herein, we show that the rapid mixing and short residence times accessible with a continuous-flow apparatus can enable the controlled polymerization of low-reactivity monomers such as δ-valerolactone and ε-caprolactone on millisecond time scales using a base [such as KOtBu or potassium bis(trimethylsilyl)amide (KHMDS)] in conjunction with a primary alcohol. These reactions exhibit characteristics capable of producing narrow dispersity with predictable molecular weights and can rapidly generate well-defined block copolymers with residence times below 0.1 s.

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Section: Introductionmentioning

confidence: 99%

Ultrafast and Controlled Ring-Opening Polymerization with Sterically Hindered Strong Bases

et al. 2020

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“…ε-Caprolactone (CL) is a cyclic lactone monomer that can be polymerized by anionic , or cationic , polymerization so that polymers with controlled structure and functionality can be synthesized. CL modification can be conducted directly at the α-carbon by electrophilic substitution via formation of an anion using a strong base or by synthesizing functionalized CL using Baeyer–Villiger oxidation.…”

Section: Introductionmentioning

confidence: 99%

Thermoresponsive Semicrystalline Poly(ε-caprolactone) Networks: Exploiting Cross-linking with Cinnamoyl Moieties to Design Polymers with Tunable Shape Memory

Garle

Kong

Ojha

et al. 2012

ACS Appl. Mater. Interfaces

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The overall goal of this study was to synthesize semicrystalline poly(ε-caprolactone) (PCL) copolymer networks with stimuli-responsive shape memory behavior. Herein, we investigate the influence of a cinnamoyl moiety to design shape memory polymer networks with tunable transition temperatures. The effect of various copolymer architectures (random or ABA triblock), the molecular weight of the crystalline domains, PCL diol, (M(w) 1250 or 2000 g mol(-1)) and its composition in the triblock (50 or 80 mol %) were also investigated. The polymer microstructures were confirmed by NMR, DSC, WAXS and UV-vis spectroscopic techniques. The thermal and mechanical properties and the cross-linking density of the networks were characterized by DSC, tensile testing and solvent swelling, respectively. Detailed thermomechanical investigations conducted using DMA showed that shape memory behavior was obtained only in the ABA triblock copolymers. The best shape memory fixity, R(f) of ~99% and shape recovery, R(r) of ~99% was obtained when PCL diol with M(w) 2000 g mol(-1) was incorporated in the triblock copolymer at a concentration of 50 mol %. The series of triblock copolymers with PCL at 50 mol % also showed mechanical properties with tunable shape memory transition temperatures, ranging from 54 °C to close to body temperature. Our work establishes a general design concept for inducing a shape memory effect into any semicrystalline polyester network. More specifically, it can be applied to systems which have the highest transition temperature closest to the application temperature. An advantage of our novel copolymers is their ability to be cross-linked with UV radiation without any initiator or chemical cross-linker. Possible applications are envisioned in the area of endovascular treatment of ischemic stroke and cerebrovascular aneurysms, and for femoral stents.

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“…More systematic kinetic studies were reported only for anionic − or pseudoanionic (covalent) polymerization of ε-caprolactone, − allowing determination of the absolute rate constants for ion pairs, free ions, and covalent species. We were able to find only two papers reporting the kinetics of chemically initiated polymerization of macrolides. , Therefore, we have performed the comparative kinetic measurements for the 6-, 7-, 9-, 12-, 13, 16, and 17-membered lactones (cf.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of the Ring-Opening Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-Membered Lactones. Comparison of Chemical and Enzymatic Polymerizations

et al. 2002

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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 - 1CH 2 OC(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 polymerizations. 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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Kinetics of Anionic Polymerization of ε-Caprolactone (εCL). Propagation of Poly-ε=CL-K⁺Ion Pairs

Cited by 33 publications

References 9 publications

Ultrafast and Controlled Ring-Opening Polymerization with Sterically Hindered Strong Bases

Ultrafast and Controlled Ring-Opening Polymerization with Sterically Hindered Strong Bases

Thermoresponsive Semicrystalline Poly(ε-caprolactone) Networks: Exploiting Cross-linking with Cinnamoyl Moieties to Design Polymers with Tunable Shape Memory

Kinetics of the Ring-Opening Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-Membered Lactones. Comparison of Chemical and Enzymatic Polymerizations

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Kinetics of Anionic Polymerization of ε-Caprolactone (εCL). Propagation of Poly-ε=CL-K+Ion Pairs

Cited by 33 publications

References 9 publications

Ultrafast and Controlled Ring-Opening Polymerization with Sterically Hindered Strong Bases

Ultrafast and Controlled Ring-Opening Polymerization with Sterically Hindered Strong Bases

Thermoresponsive Semicrystalline Poly(ε-caprolactone) Networks: Exploiting Cross-linking with Cinnamoyl Moieties to Design Polymers with Tunable Shape Memory

Kinetics of the Ring-Opening Polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-Membered Lactones. Comparison of Chemical and Enzymatic Polymerizations

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Kinetics of Anionic Polymerization of ε-Caprolactone (εCL). Propagation of Poly-ε=CL-K⁺Ion Pairs