Catalyst‐Free Vitrimer Cross‐Linked by Biomass‐Derived Compounds with Mechanical Robustness, Reprocessability, and Multishape Memory Effects

Abstract

Vitrimerization of thermoset polymers plays an important role in addressing resource recovery and reuse. Vitrimer elastomers with good mechanical properties often require well-designed crosslinking agents or fillers, but this increases processing complexity or reduces vitrimer dynamic properties. In this report, a simple green strategy to build a strong vitrimer elastomer is designed. Commercially available epoxidized natural rubber (ENR) is cross-linked with biomass-derived D-Fructose 1,6-bisphosphoric acid to get a vitrimer elastomer cross-linked by 𝜷-hydroxy phosphate ester bonds and has abundant hydrogen bonds. Hydrogen bonds can preferentially break and dissipate energy under external forces, which makes the sample robust. The topological network can be reformed at high temperatures through the dynamic exchange of 𝜷-hydroxy phosphate ester bonds, which gives the material malleability and recyclability. In addition, through the strategy of combining reprocessing and welding, multiple shape memory effects can be achieved in one postprocessing step. Considering that a variety of commercially available epoxy polymers are easily available, it is believed that this strategy can be a simple and versatile way to enable commercial epoxy polymers to achieve green crosslinking through biomass crosslink agents, which results in robust and recyclable vitrimers based on 𝜷-hydroxy phosphate bonds.

Biodegradable-Renewable Vitrimer Fabrication by Epoxidized Natural Rubber and Oxidized Starch with Robust Ductility and Elastic Recovery

“…However, the intensity of the 13 C characteristic peak attributed to OST (C 1∼6 ) decreased significantly, indicating that a large amount of OST is significantly degraded and removed from ENR. In addition, the retention of the 13 C characteristic peak of the ester bond at 178 ppm after enzymatic hydrolysis confirmed that α-amylase degraded OST by attacking the 1,4-glycosidic bond rather than the ester bond. − …”

RNA-inspired phosphate diester dynamic covalent networks

“…Previous studies assumed these moieties to show associative network rearrangement, but did not investigate this further. 37,38 Variable temperature 31 P solid-state NMR (VT 31 P SSNMR) experiments were conducted to verify the dissociative network rearrangement as indicated by our rheology experiments. PEG-dP-TEA was allowed to equilibrate in the spectrometer at 60 °C, after which the temperature was increased to 120 °C with intervals of 20 °C.…”

“…35,36 Using β-hydroxy containing phosphate diesters in DCNs is therefore a promising approach to obtain dynamic, yet hydrolytically stable materials. The usage of βand γ-hydroxy containing phosphate esters has been reported by other groups, 37,38 but mechanistic aspects of diester transesterification in these materials were not studied in detail. Furthermore, the used synthetic method is known to yield a mixture of phosphate mono-, di-and triesters, complicating mechanistic studies.…”

Green and Catalyst-Free Cross-Linking of Bio-Based Elastomers toward Robust, Reprocessable Abilities and Improved Thermal Aging Resistance Enabled by β-Hydroxyl Esters

“…33 These elastomeric vitrimers were endowed with good malleability and reprocessability in the presence of a transesterification catalyst at high temperature. Bai et al 34 reported that ENR was crosslinked with biobased D-fructose 1,6-bisphosphoric acid under the catalysis of DMI, producing exchangeable β-hydroxy phosphate ester bonds. The obtained material had good recyclability and multiple shape memory behavior.…”