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Feeding behaviour is modulated by both environmental cues and internal physiological states. Appetite is commonly boosted by the pleasant smell (or appearance) of food and destroyed by a bad taste. In reality, animals sense multiple environmental cues at the same time and it is not clear how these sensory inputs are integrated and a decision is made to regulate feeding behaviour accordingly. Here we show that feeding behaviour in Caenorhabditis elegans can be either facilitated by attractive odours or suppressed by repellents. By identifying mutants that are defective for sensory-mediated feeding regulation, we dissected a central flip-flop circuit that integrates two contradictory sensory inputs and generates bistable hormone output to regulate feeding behaviour. As feeding regulation is fundamental to animal survival, we speculate that the basic organizational logic identified here in C. elegans is likely convergent throughout different phyla.

The use of soybean oil or its derivatives to toughen polylactide (PLA) usually leads to limited toughening efficiency, due to the incompatibility between toughening agents and parent PLA. Herein, we report a dynamic vulcanization method to toughen PLA using sebacic acid cured epoxidized soybean oil (VESO), a fully sustainable and biodegradable component. A series of sebacic acid cured epoxidized soybean oil precursors (SEPs) were prepared with different carboxyl/epoxy equivalent ratio (R), which consequently dictates the chemical structure and the morphology of PLA/VESO blends after the dynamic vulcanization. We demonstrated that the chemical structure of VESO plays a critical role in the compatibility, morphology, and toughness of the PLA/VESO blends. By optimizing the R-value, supertoughened PLA blends can be obtained, as evidenced by the significant improvement in the tensile toughness (up to 150.6 MJ/m3) and the impact strength (up to 542.3 J/m). The results of the toughening mechanism from the morphology study confirm that the chemical structure of VESO is the key indicator of the toughening efficiency. For the PLA/VESO blends, at optimized R-value, the fracture energy can be dissipated efficiently through shear yielding of the PLA matrix induced by internal VESO cavitation to achieve supertoughness.

Epoxidized soybean oil (ESO)-derived epoxy thermosets are usually limited by their poor mechanical properties and non-reprocessability. Herein, we report sustainable epoxy vitrimers synthesized facilely by curing ESO with vanillin-derived Schiff base (VSB) dynamic hardener with 1,2-dimethylimidazole as an accelerator. The phenolic hydroxyl of VSB showed high reactivity toward the epoxy group of ESO with a curing activation energy of 108.9 kJ•mol −1 . The network rigidness and cross-link density of the epoxy vitrimers are adjustable by simply changing the feed ratio of flexible ESO and rigid VSB, which enables us to tailor the mechanical properties of the vitrimers easily over a wide range from soft to tough and hard. The dynamic Schiff base bonds provide the epoxy vitrimer with excellent reprocessability, weldability, reconfigurability, and programmability, which facilitates the recycling and processing of the cured epoxy materials. With tunable mechanical properties, reprocessability, and multifunctionality, the ESO-derived epoxy vitrimers are of great potential as alternatives to traditional epoxy thermosets.

In this study, we report the curing of ESO with biobased dicarboxylic acids (DCAs) with different carbon chain-lengths to synthesize fully sustainable polymers. Both non-isothermal and isothermal curing processes analysis indicated that the curing rate and activation energy decreased with increasing chain-length of DCAs. The optimum-COOH/epoxy molar ratio is 0.7 for preparation of ESO/DCA cured product with maximum degree of crosslinking. Addition of 4-N, N-dimethylaminopyridine (DMAP) as a catalyst can efficiently accelerate the curing rate and reduce activation energy. We systemtically studied the effect of chain-length of DCAs on the physical properties of cured products, and found that with increase in chain-length of DCAs, the glass transition temperature of the cured ESO/DCA decreased, the tensile strength and Young's modulus increased while elongation at break decreased, due to the decreased crosslinking density resulted from the increased chain-length between crosslinking sites. All cured ESO/DCA showed excellent thermal stability with initial decomposition temperature of higher than 340 °C.

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A novel biobased epoxy vitrimer (Gte-VA) with desirable mechanical properties was synthesized from glycerol triglycidyl ether (Gte) and an imine-containing hardener (VA), which was also a biobased compound from vanillin and 4aminophenol. The biobased epoxy vitrimer shows Young's modulus of 1.6 GPa and tensile strength of 62 MPa, which is close to the value of amine-cured bisphenol A diglycidyl ether. In addition, it shows excellent reprocessability, recyclability, and UV shielding performance and can be used as a matrix to prepare carbon fiber (CF)-reinforced composites. Based on the amine− imine reversible exchange reaction of the imine bonds, the CF fabric could be recycled without damage from the composite, after degrading the resin in an amine solution. Especially, after recombining the degraded resin with recycled carbon fiber fabric, a regenerated carbon fiber reinforced composite with similar mechanical properties to the original composite can be obtained, achieving full recycling of the carbon fiber reinforced composite. This work will open a door to the development of simple procedures of high-performance biobased epoxy vitrimer and its application in fully recycled carbon fiber reinforced composite.