Facile Mechanochemical Synthesis of Malleable Biomass-Derived Network Polyurethanes and Their Shape-Memory Applications

Abstract

Because of the environmental issues associated with thermoset or network polymers, recyclable polymers are highly in demand, and the use of sustainable biomass-derived ingredients is also becoming increasingly important. In this work, we utilized 2,5bis(hydroxymethyl)furan as a starting material to produce network polyurethanes (NPUs) under facile, solvent-free (solid-state) ball milling conditions. Urethane bonds may undergo thermally controlled transcarbamoylation, a reversible dynamic covalent bond exchange, enabling reshaping of NPUs. Taking advantage of this chemistry, we demonstrate the self-healing, reprocessing, and shapememory properties of biomass-derived NPU films using mesoerythritol as a cross-linking agent. Interestingly, in urethane-bondforming reactions, the relative reactivity of the secondary alcohol group of meso-erythritol over the primary one is remarkably different in the solid state, resulting in NPU films with much enhanced mechanical properties. Dynamic mechanical thermal and stress relaxation analyses indicate that the NPU films possess typical characteristics of vitrimers, such as constant cross-link density and Arrhenius-like reduction in viscosity at elevated temperatures, even though the dissociative exchange of urethane bonds may work here. Our mechanochemical approach is facile and scalable, enabling the preparation of sustainable and recyclable polymers from various biomass-derived chemicals.

Reprocessable, Self-Adhesive, and Recyclable Carbon Fiber-Reinforced Composites Using a Catalyst-Free Self-Healing Bio-Based Vitrimer Matrix

“…All these peaks confirm the degradation mechanism. Notably, the degradation products of the TOTGE–MDA vitrimer matrix are polyols, which can be used as potential cross-linking agents for bio-based polyurethanes, as previously reported. , …”

“…As the ratio of active hydrogen/epoxy groups increases from 0.6 to 1.0, the storage modulus ( E ′) of the TOTGE–MDA vitrimer at 25 °C increases from 1426 to 1964 MPa. The cross-link density is obtained by the value of E ″ ( T g + 30 °C) according to Flory’s ideal rubber elasticity theory. − As the ratio increases, the cross-link density of the TOTGE–MDA vitrimers increases from 0.87 × 10 –3 to 1.20 × 10 –3 mol/cm 3 (Table ). Generally, the gel content is proportional to the cross-link density of the network. , As the ratio increases from 0.6 to 1.0, the gel content increases from 94.1 ± 0.9 to 99.4 ± 0.2%, which also confirms an increase in the cross-link density.…”

“…Notably, the degradation products of the TOTGE−MDA vitrimer matrix are polyols, which can be used as potential cross-linking agents for bio-based polyurethanes, as previously reported. 49,64 Figure 7a shows the chemical degradation of the TOTGE− MDA−CF composite in EA. With increasing time, the solution changed from colorless to yellow, and finally the matrix was completely dissolved in EA, leaving behind only CFs.…”

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

“…Even if lignin, vegetable oils and sugar derivatives were used as polyols, the diisocyanate was in all cases petroleumbased. [116][117][118] For this reason, and the classification of isocyanates as CMR substances, these studies are not described this review.…”

Self-Healable and Recyclable Biomass-Derived Polyurethane Networks through Carbon Dioxide Immobilization

“…In this study, we prepared biomass-derived urethane-based network polymers using a FCD, a new platform derived from the direct immobilization of CO 2 into BHMF [2,[51][52][53]. The synthesized PCU network polymers were fabricated into films (Figure 1) and their thermal and thermomechanical properties were thoroughly characterized.…”