Facile synthesis of “digestible”, rigid-and-flexible, bio-based building block for high-performance degradable thermosetting plastics

Abstract

A bio-sourced, low-toxic monomer was facilely synthesized and used to build controlled degradable, strong and tough thermosetting plastics.

High-Performance, Biobased, Degradable Polyurethane Thermoset and Its Application in Readily Recyclable Carbon Fiber Composites

“…The six-membered heterocyclic structure in HMDO is considered to have a certain ability to reduce the initial thermal decomposition rate of plastics in the presence of air. 15 The mechanical properties can also be affected by the flexibility of chain segment and their cross-link density. As can be seen in Figure 3, PU-HMDO has a little lower tensile strength (68 MPa) and tensile modulus (1638 MPa) and a little higher elongation at break (7.9%) than PU-BPA.…”

“…Herein, a biobased degradable PU thermoset was facilely prepared by reacting a biobased diol containing monocyclic acetal structure 15 with trifunctional isocyanate. The thermal and mechanical performance, degradability, and chemical stability of the PU thermoset were systematically studied.…”

“…Preparation of PU-HMDO and PU-BPA. First, 10 g (0.0442 mol) of (2-(4-hydroxy-3-methoxyphenyl)-1,3-dioxan-5-ol) HMDO (synthesized according to the method in our previous work 15 ) (or 10 g (0.0438 mol) of BPA) and 16.36 g (0.0324 mol) (or 16.21 g (0.0321 mol)) of HDI trimer with the molar ratio of hydroxyl group (−OH) to isocyanate group (−NCO) of 1:1.1 were dissolved in 50 g of DMF (or acetone) (solid content is 34.5 wt % for the PU-HMDO system in DMF and 34.4 wt % for the PU-BPA system in acetone) and then evaporated by rotary evaporator to remove DMF at 80 °C (or at 50 °C to remove acetone) (the removal of DMF in the obtained solution is proved in Figure S1). After the DMF (or acetone) was removed, a transparent mixture was obtained and then placed into a 5 cm × 5 cm × 0.4 mm mold.…”

Design of controllable degradable epoxy resin: High performance and feasible upcycling

“…A large amount of hydroxypropyl amine groups in cured DVPM-DGEBA could increase the formation of intraor inter-molecular hydrogen bonds with the methoxyl groups and lead to the increase of glassy modulus. 32,39 The decrease of storage modulus is mainly caused by the breakage of hydrogen bonds in the crosslinked networks, 17,39 which accelerates chain movements and decrease the rigidity of segment structure at higher temperature. As shown in Figure 2D, the existence of hydrogen bonds was confirmed by non-isothermal FT-IR spectra, and the signals for hydroxyl group shifted to the higher wavenumber as the temperature increased, due to the breaking of hydrogen bond.…”

“…Recently, the introduction of labile bonds or units (complex chemical structure including labile bonds), including ester bonds, 8–10 disulfide linkages, 11,12 Schiff‐base, 13–15 acetal linkages, 16–19 and hexahydro‐s‐triazine structures, 20–22 has been regarded as a feasible approach to synthesize degradable or recyclable epoxy resins. However, epoxy resins containing labile bonds will disorderly degrade into complex organic compounds under acidic or basic condition, which makes it difficult to separate and purify degradation products.…”