The design of high glass transition temperature (T g ) thermoset materials with considerable reparability is a challenge. In this study, a novel biobased triepoxy (TEP) is synthesized and cured with an anhydride monomer in the presence of zinc catalyst. The cured TEP exhibits a high T g (187 °C) and comparable strength and modulus to the cured bisphenol A epoxy. By adopting the vitrimer chemistry, the cross-linked polymer materials are imparted significant stress relaxation and reparability via dynamic transesterification. It is noted that the reparability is closely related to the repairing temperature, external force, catalyst content, and the magnitude of rubbery modulus of the sample. The width of the crack from the cured TEP can be efficiently repaired within 10 min. This work introduces the first high-T g biobased epoxy material with excellent reparability and provides a valuable method for the design of high-T g self-healing materials suitable for high service temperature.

This work introduces a simple and green method for the preparation of a fully biobased vitrimer material and demonstrates a potential application for recoverable adhesives.

This work presents a solvent-free, facile synthesis of a renewable, aromatic monomer, methacrylated eugenol (ME), from eugenol and methacrylic anhydride by the Steglich esterification reaction. The resulting ME was subsequently used as a reactive diluent to copolymerize with a commercial maleinated acrylated epoxidized soybean oil (MAESO) resin to form renewable MAESO–ME thermosets. The volatility of ME was examined, along with an analysis of viscosity and curing behavior of the MAESO–ME mixtures. The curing kinetics, thermo-mechanical properties, and thermal stabilities of the fully cured MAESO–ME thermosets with different ME proportions (0%, 20%, 40%, 60%, 80%, and 100%) were systematically investigated. The results indicated that ME monomer exhibited extremely low volatility (less than 3% mass loss after being held isothermally at 30 °C for 10 h), high biobased carbon content (BBC, 71.4%), and low viscosity (17.6 cP at 25 °C). Upon use with MAESO resin, viscosity of the system was considerably decreased. Compared with per equivalent of MAESO, ME-diluted systems exhibited higher reactivity, which resulted in improved curing extent and higher cross-link density of the MAESO–ME systems. The glass transition temperature (T g) of MAESO–ME thermosets greatly improved from 61.1 to 139.3 °C with increasing ME loading from 0% to 100%. Overall, the developed biobased ME monomer is shown to be an effective, sustainable reactive diluent to replace styrene for commercially available MAESO resin.

Tetrafunctional epoxy is an indispensable matrix for the aerospace industry, high-temperature adhesives, and encapsulation materials, where high service temperatures (>220 °C) are required. N,N,N′,N′-Tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) has long been the dominant candidate in those applications; however, fully cured TGDDM epoxy materials suffer from poor toughness, unwanted side reactions, and inadequate moisture resistance. A novel tetrafunctional epoxy, TFTE, is synthesized to address those issues, which have not been resolved for decades. TFTE can be prepared through a simple three-step procedure using readily available raw materials. Each step shows a high yield (>90%) and involves only mild reaction conditions. When TFTE is mixed with diglycidyl ether of bisphenol A (DGEBA) and cured with 4,4′-diaminodiphenylsulfone (DDS), the cured epoxy shows a T g value of 252 °C, a tensile strength of 80.0 MPa, and, more importantly, a higher toughness (29.8 kJ/m2) and better moisture resistance than the TGDDM/DDS system. In addition, the interfacial strength, thermal stability, and processability of TFTE/DGEBA are comparable to those of TGDDM. These excellent properties and processability make TFTE a potential replacement for TGDDM.

Developing vegetable oil-derived primary plasticizers for poly(vinyl chloride) (PVC) is still a challenge because of their insufficient compatibility. As described in this work, we report the synthesis of plasticizers through the esterification of polyethylene glycol methyl ether and dimer acid, in which dimer acid is renewable material prepared via a two-step reaction (1) the hydrolysis of fatty acids from soybean oil at 70 °C and (2) subsequent Diels–Alder reaction at 250 °C. The resulting plasticizers, dimer acid-derived polyethylene glycol methyl ether esters (DA-2n, 2n = 2, 4, 6 or 8 referring to the number of oxethyl units per molecule), were blended with PVC. It was found that the tensile properties, transparency, and thermal stability of plasticized PVC (PVC-DA-2n) increased significantly with an increase in the number of oxyethyl units. Fourier-transform infrared spectroscopy analysis revealed that its good compatibility can be attributed to the strong interaction between oxyethyl units and PVC. As the number of the oxyethyl units of plasticizer increased, the glass transition temperature (Tg) of the corresponding plasticized PVC samples decreased from 62.3 (PVC-DA-2) to 35.4 °C (PVC-DA-8). Owing to the excellent plasticization of DA-8, the performances of PVC-DA-8 were comparable or better than that of the PVC plasticized using commercial dioctyl terephthalate (DOTP). The simple but efficient method of this study provides a new avenue for the preparation of vegetable oil-based plasticizers for PVC.