Macrocycles, 1. Macrocyclic polymerizations of (thio)lactones – stepwise ring expansion and ring contraction

Kricheldorf, Hans R.; Lee, Soo‐Ran; Schittenhelm, Nicole

doi:10.1002/(sici)1521-3935(19980201)199:2<273::aid-macp273>3.3.co;2-4

Cited by 64 publications

(11 citation statements)

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“…I studied the reactions of several less common monomers with the cyclic dibutyl tin alkylene oxides 1a or 1c 28–30. The reactions of γ‐thiobutyrolactone proved to be particularly interesting.…”

Section: Homopolymerizationsmentioning

confidence: 99%

“…However, this thiolactone makes a one‐step insertion into SnO bonds because in this way a thermodynamically more stable SnS bond is formed (eq 9). 28 The structure of the cyclic reaction products 23a – 23c was proven not only by 1 H, 13 C, and 119 Sn NMR spectroscopy but also by mass spectrometry. When the freshly prepared hot solution of spirocyclic initiator 16a was treated with an excess of γ‐thiobutyrolactone, spirocycle 24 was obtained, the structure of which was proven by NMR spectroscopy and fast atom bombardment mass spectrometry.…”

Section: Homopolymerizationsmentioning

confidence: 99%

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Biodegradable polymers with variable architectures via ring‐expansion polymerization

Kricheldorf

2004

J. Polym. Sci. A Polym. Chem.

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107

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Kinetically controlled ring‐expansion polymerizations (REPs) are defined syntheses generating cyclic oligomers and polymers without linear intermediates and without equilibration reactions. This review reports syntheses of cyclic metal alkoxides and their use as initiators for REPs of lactones, cyclic diesters, and cyclocarbonates. In addition to homopolyesters, telechelic oligoesters or polyesters, random copolyesters, and A–B–A triblock copolymers can be prepared by these REPs. The in situ combination of REPs with condensation (mostly acylation) reactions allows a broad variation of end groups. The in situ combination of REPs with polycondensation enables various chain‐extension reactions, including the syntheses of multiblock copolymers. With spirocyclic initiators, four‐armed stars with functional end groups may be prepared. The in situ combination of REPs with condensation reactions of trifunctional or multifunctional reagents makes a broad variety of networks accessible. The average segment lengths may be controlled via the monomer/initiator ratios of the REP. All materials produced via the aforementioned REP processes are biodegradable and nontoxic, and this allows for biomedical and pharmaceutical applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4723–4742, 2004

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Section: Homopolymerizationsmentioning

confidence: 99%

Section: Homopolymerizationsmentioning

confidence: 99%

Biodegradable polymers with variable architectures via ring‐expansion polymerization

Kricheldorf

2004

J. Polym. Sci. A Polym. Chem.

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107

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“…catalyzed ROP of tCL from alcohol or thiol initiators in solvent or bulk, 11,12 and a ring-expansion polymerization technique has also been demonstrated. 13 A recent report of the ROP of ε -thiocaprolactone, tCL, used a lipase typically employed in esterification 14,15 to yield poly( ε -thionocaprolactone) (PtCL) with higher M w / M n than poly( ε -caprolactone) (PCL) generated under identical conditions. This report demonstrates the extension of mild techniques for the ROP of esters to thioesters.…”

Section: Introductionmentioning

confidence: 99%

Poly(thioester) by Organocatalytic Ring-Opening Polymerization

Bannin

Kiesewetter

2015

Macromolecules

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Organocatalysts typically used for the ring-opening polymerization (ROP) of cyclic ester monomers are applied to a thiolactone, ε-thiocaprolactone (tCL). In the absence of an H-bond donor, a nucleophilic polymerization mechanism is proposed. Despite the decreased ability of thioesters and thiols (versus esters and alcohols) to H-bond, H-bonding organocatalysts—a thiourea in combination with an H-bond accepting base—are also effective for the ROP of tCL. The increased nucleophilicity of thiols (versus alcohols) is implicated in the increased Mw/Mn of the poly(thiocaprolactone) versus poly(caprolactone), but deleterious transesterification is suppressed in the presence of a thiourea. The thioester monomer, tCL, is shown to be thermodynamically similar to ε-caprolactam but kinetically similar to ε-caprolactone.

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“…Figure shows an example for the ring‐expansion reaction. Here, the molecular weights are difficult to control because they are not related to the monomer/initiator ratio . Furthermore, the remaining tin species raise several issues regarding the polymer hydrolysis and toxicity, given their potential applications.…”

Section: Generalization Of Existing Synthetic Stylesmentioning

confidence: 99%

“…Therefore, it is necessary to remove the retaining tin species while maintaining the cyclic structures. In this regard, a couple of methods have been developed, either to exchange the tin groups with other links or further cross link the branch chains to form a new macrocycle …”

Section: Generalization Of Existing Synthetic Stylesmentioning

confidence: 99%

Advanced Developments in Cyclic Polymers: Synthesis, Applications, and Perspectives

Zhu

Hosmane

2015

ChemistryOpen

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Due to the topological effect, cyclic polymers demonstrate different and unique physical and biological properties in comparison with linear counterparts having the same molecular-weight range. With advanced synthetic and analytic technologies, cyclic polymers with different topologies, e.g. multicyclic polymers, have been reported and well characterized. For example, various cyclic DNA and related structures, such as cyclic duplexes, have been prepared conveniently by click chemistry. These types of DNA have increased resistance to enzymatic degradation and have high thermodynamic stability, and thus, have potential therapeutic applications. In addition, cyclic polymers have also been used to prepare organic–inorganic hybrids for applications in catalysis, e.g. catalyst supports. Due to developments in synthetic technology, highly pure cyclic polymers could now be produced in large scale. Therefore, we anticipate discovering more applications in the near future. Despite their promise, cyclic polymers are still less explored than linear polymers like polyolefins and polycarbonates, which are widely used in daily life. Some critical issues, including controlling the molecular weight and finding suitable applications, remain big challenges in the cyclic-polymer field. This review briefly summarizes the commonly used synthetic methodologies and focuses more on the attractive functional materials and their biological properties and potential applications.

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Macrocycles, 1. Macrocyclic polymerizations of (thio)lactones – stepwise ring expansion and ring contraction

Cited by 64 publications

References 0 publications

Biodegradable polymers with variable architectures via ring‐expansion polymerization

Biodegradable polymers with variable architectures via ring‐expansion polymerization

Poly(thioester) by Organocatalytic Ring-Opening Polymerization

Advanced Developments in Cyclic Polymers: Synthesis, Applications, and Perspectives

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