Fully Biobased Vitrimers: Future Direction toward Sustainable Cross‐Linked Polymers

Abstract

Improving the sustainability of polymer networks is a crucial challenge in polymer science due to their important role in industry. Their traditional syntheses conflict with several principles of green chemistry as the employed monomers are petroleum-based, their production involves the use of toxic reagents, and their permanently cross-linked structures impede their chemical recycling and reshaping. The development of vitrimers represents a unique solution to address the issue of polymer network end-of-life by enabling reprocessability while maintaining good thermomechanical properties and solvent resistance. Although over the last decades biomass has proved to be an excellent feedstock for the production of permanently cross-linked polymers, the field of biobased vitrimers is still in its infancy. In this review, a comprehensive overview of vitrimers synthesized from biobased monomers is presented. The emphasis is set on the compatibility of the biomass structure with the nature of the dynamic covalent chemistry, as well as the sustainability of the synthetic approaches. Implementing renewable feedstocks and recyclability in the production of polymer networks paves the way for the development of the next generation of sustainable materials.

Fully biomass-derived vitrimeric material with water-mediated recyclability and monomer recovery

“…34,35 For instance, many reports of bio-derived CANs have surfaced in recent years in an effort to utilise renewable feedstock. 36 In these examples, there have been efforts to demonstrate the material's recyclability by mechanical reprocessing or chemical degradation; 37,38 some have even examined polymer biodegradability. 39 However, to date, very limited works have demonstrated the full recovery and isolation of monomers from CANs.…”

Biobased covalent adaptable networks: towards better sustainability of thermosets

“…A series of fruitful achievements has been accomplished for biobased CANs, but they have not been reviewed systematically, although some review papers have been published on biobased vitrimers. 72 Therefore, a comprehensive review is highly desired to summarize the current progress in biobased CANs to facilitate future research. Herein, we present a review of biobased CANs.…”

Recyclable Vitrimers from Biogenic Poly(itaconate) Elastomers

“…27−30 However, the most common vitrimers make use of a design based on dynamic transesterification reactions. 10,20,31,32 These structures are popular due to accessible monomers and a facile reaction control by the variation of the required Lewis acid catalyst.…”

“…With the proper structural design or catalyst loading, these permanently cross-linked networks can be reprocessed. − Vitrimer materials behave in a similar way to silica, providing a weak and gradual change of viscosity as a function of temperature, which is based on the bond exchange dynamics and their constant stress relaxation. Moreover, at high temperatures and constant deformation, these systems show a gradual transition from a thermoset or an elastomer to a viscous liquid. ,,− Various vitrimer systems that include transalkylation, transamination, or disulfide exchange have been reported so far. − However, the most common vitrimers make use of a design based on dynamic transesterification reactions. ,,, These structures are popular due to accessible monomers and a facile reaction control by the variation of the required Lewis acid catalyst.…”

“…The use of petrochemical monomers is constantly growing, which represents a significant challenge due to the limited availability of fossil resources. Therefore, increasing efforts are aimed at the development of materials from sustainable feedstocks. ,,,− Various biobased elastomers and thermosets have evolved from renewable platform chemicals like itaconic acid, eugenol, lignin, or vegetable oils. ,,− To combine recyclability and renewability, various biobased vitrimers that rely on transesterification reactions have been developed. These systems are typically epoxy-based and make use of a polyester backbone. ,, This vitrimer chemistry exhibits a simultaneous polymerization and cross-linking process without the use of any initial prepolymer system or a cross-linker, which limits the tunability of the material properties and its applicability for specific applications. , To the best of our knowledge, there is no literature report for side-chain-modified itaconic acid-based or molecularly dissolved vitrimer prepolymer systems, and previous itaconic acid-based vitrimer networks were obtained via epoxy ring-opening polymerization or polycondensation chemistry. , To account for this shortcoming, we herein introduce the use of functionalized itaconic acid vinyl monomers and their polymerization using free radical copolymerization to obtain a cross-linkable prepolymer.…”