Synthesis and cationic ring-opening polymerization of mono- and bifunctional spiro orthoesters containing ester groups and depolymerization of the obtained polymers: An approach to chemical recycling for polyesters as a model system

Yoshida, Kohei; Sanda, Fumio; Endō, Takeshi

doi:10.1002/(sici)1099-0518(19990715)37:14<2551::aid-pola28>3.0.co;2-p

Cited by 19 publications

(9 citation statements)

References 14 publications

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“…acid, succinic acid, and 1,4-cyclohexanedicarboxylic acid were reported by Yoshida et al 109 They found that the resulting thermoset could be depolymerized to regenerate the original monomers. Similar structures containing bicyclo orthoester moieties were explored by Hitomi et al 110 By grafting the functional groups on the polymer side chains, they were able to de-cross-link the thermosets leading to regeneration of the starting linear polymers.…”

Section: Triggered Degradation With Matrix Recyclingmentioning

confidence: 88%

A Review on the Potential and Limitations of Recyclable Thermosets for Structural Applications

et al. 2019

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The outstanding performance of conventional thermosets arising from their covalently cross-linked networks directly results in a limited recyclability. The available commercial or close-to-commercial techniques facing this challenge can be divided into mechanical, thermal, and chemical processing. However, these methods typically require a high energy input and do not take the recycling of the thermoset matrix itself into account. Rather, they focus on retrieving the more valuable fibers, fillers, or substrates. To increase the circularity of thermoset products, many academic studies report potential solutions which require a reduced energy input by using degradable linkages or dynamic covalent bonds. However, the majority of these studies have limited potential for industrial implementation. This review aims to bridge the gap between the industrial and academic developments by focusing on those which are most relevant from a technological, sustainable and economic point of view. An overview is given of currently used approaches for the recycling of thermoset materials, the development of novel inherently recyclable thermosets and examples of possible applications that could reach the market in the near future.

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Section: Triggered Degradation With Matrix Recyclingmentioning

confidence: 88%

A Review on the Potential and Limitations of Recyclable Thermosets for Structural Applications

et al. 2019

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“…Although the polymer was isolated in 52 % yield at 0 °C, the equilibrium shifts at a higher temperature (30 °C) to the side of the monomer 41 (19 % yield of polymer). In this case, the polymer network could be recycled to a bifunctional monomer 70…”

Section: Equilibrium (Dynamic) Polymerizationsmentioning

confidence: 99%

Dynamic Covalent Chemistry

Rowan,

Cantrill,

Cousins

et al. 2002

Angew. Chem. Int. Ed.

2,426

1,334

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Dynamic covalent chemistry relates to chemical reactions carried out reversibly under conditions of equilibrium control. The reversible nature of the reactions introduces the prospects of “error checking” and “proof‐reading” into synthetic processes where dynamic covalent chemistry operates. Since the formation of products occurs under thermodynamic control, product distributions depend only on the relative stabilities of the final products. In kinetically controlled reactions, however, it is the free energy differences between the transition states leading to the products that determines their relative proportions. Supramolecular chemistry has had a huge impact on synthesis at two levels: one is noncovalent synthesis, or strict self‐assembly, and the other is supramolecular assistance to molecular synthesis, also referred to as self‐assembly followed by covalent modification. Noncovalent synthesis has given us access to finite supermolecules and infinite supramolecular arrays. Supramolecular assistance to covalent synthesis has been exploited in the construction of more‐complex systems, such as interlocked molecular compounds (for example, catenanes and rotaxanes) as well as container molecules (molecular capsules). The appealing prospect of also synthesizing these types of compounds with complex molecular architectures using reversible covalent bond forming chemistry has led to the development of dynamic covalent chemistry. Historically, dynamic covalent chemistry has played a central role in the development of conformational analysis by opening up the possibility to be able to equilibrate configurational isomers, sometimes with base (for example, esters) and sometimes with acid (for example, acetals). These stereochemical “balancing acts” revealed another major advantage that dynamic covalent chemistry offers the chemist, which is not so easily accessible in the kinetically controlled regime: the ability to re‐adjust the product distribution of a reaction, even once the initial products have been formed, by changing the reaction's environment (for example, concentration, temperature, presence or absence of a template). This highly transparent, yet tremendously subtle, characteristic of dynamic covalent chemistry has led to key discoveries in polymer chemistry. In this review, some recent examples where dynamic covalent chemistry has been demonstrated are shown to emphasise the basic concepts of this area of science.

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“…In the presence of Bronsted and Lewis acids, SOEs polymerize by cationic double-ring opening reaction, yielding poly(ether ester)s ( Figure 10 B). For the polymerization of seven-membered SOEs at low temperatures, single ring-opening polymerization upon the formation of poly(cyclic orthoester)s was reported [ 62 ]. At temperatures above 100 °C, the poly(cyclic orthoester)s undergo isomerization yielding poly(ether ester)s.…”

Section: Expanding Oxacyclesmentioning

confidence: 99%

Expanding Monomers as Anti-Shrinkage Additives

Marx

Wiesbrock

2021

Polymers

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Commonly, volumetric shrinkage occurs during polymerizations due to the shortening of the equilibrium Van der Waals distance of two molecules to the length of a (significantly shorter) covalent bond. This volumetric shrinkage can have severe influence on the materials’ properties. One strategy to overcome this volumetric shrinkage is the use of expanding monomers that show volumetric expansion during polymerization reactions. Such monomers exhibit cyclic or even oligocyclic structural motifs with a correspondingly dense atomic packing. During the ring-opening reaction of such monomers, linear structures with atomic packing of lower density are formed, which results in volumetric expansion or at least reduced volumetric shrinkage. This review provides a concise overview of expanding monomers with a focus on the elucidation of structure-property relationships. Preceded by a brief introduction of measuring techniques for the quantification of volumetric changes, the most prominent classes of expanding monomers will be presented and discussed, namely cycloalkanes and cycloalkenes, oxacycles, benzoxazines, as well as thiocyclic compounds. Spiroorthoesters, spiroorthocarbonates, cyclic carbonates, and benzoxazines are particularly highlighted.

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Synthesis and cationic ring-opening polymerization of mono- and bifunctional spiro orthoesters containing ester groups and depolymerization of the obtained polymers: An approach to chemical recycling for polyesters as a model system

Cited by 19 publications

References 14 publications

A Review on the Potential and Limitations of Recyclable Thermosets for Structural Applications

A Review on the Potential and Limitations of Recyclable Thermosets for Structural Applications

Dynamic Covalent Chemistry

Expanding Monomers as Anti-Shrinkage Additives

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