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Cross-linked poly(ε-caprolactone) (PCL)-based polyesterurethane (PUR) systems have been synthesized through Diels-Alder reactions by reactive extrusion. The Diels-Alder and retro-Diels-Alder reactions proved to be useful for enhancing the molecular motion of PCL-based systems, and therefore their crystallization ability, in the design of cross-linked semicrystalline polymers with one-way and two-way shape-memory properties. Successive reactions between α,ω-diol PCL (PCL(2) ), furfuryl alcohol, and methylene diphenyl 4,4'-diisocyanate straightforwardly afforded the α,ω-furfuryl PCL-based PUR systems, and subsequent Diels-Alder reactions with N,N-phenylenedimaleimide afforded the thermoreversible cycloadducts. The cross-linking density could be modulated by partially replacing PCL-diol with PCL-tetraol. Interestingly, the resulting PUR systems proved to be semicrystalline cross-linked polymers, the melting temperature of which (close to 45 °C) represented the switching temperature for their shape-memory properties. Qualitative and quantitative measurements demonstrated that these PUR systems exhibited one-way and two-way shape-memory properties depending on their cross-linking density.

Soda lignin was functionalized with tert-butyldimethylsilyl groups by the reaction with tert-butyldimethylsilyl chloride. The reaction conditions leading to a quantitative derivatization of lignin, hydroxyl groups were determined by 31 P and 1 H NMR and compared with those of acetylation. The functionalization was also confirmed by FTIR and size exclusion chromatography. The silylation enhances the thermal stability and lowers the T g of lignin as compared to the acetylation. In addition, the silylated lignins are soluble in a wider range of organic solvents, including solvents of low polarity and show a clear hydrophobic character with a contact angle with water higher than 100°. Neat, acetylated, and silylated lignins were then blended with low density polyethylene, and injection molded materials were analyzed with tensile tests, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). This study reveals the higher compatibility of the silylated lignin with the polyolefin matrix and hence the great potential of the silylated lignin for a use as an additive in apolar polymer matrices.

This work describes new fully bio-based vitrimers prepared from isosorbide, a renewable sugar-based chemical. Isosorbide was reacted with 4-hydroxypropionic acid, paraformaldehyde, mono-ethanolamine, and/or furfurylamine via consecutive solvent-free Fischer esterification and Mannich-like ring-closure reactions. The two-step synthesis led to the formation of a ditelechelic benzoxazine-terminated isosorbide monomer, containing ester bonds and aliphatic hydroxyl and/or furan groups. The atom economy factor yields 85%. The structural features of the resulting products were substantiated by spectroscopic techniques. The ringopening polymerization was monitored by rheological and differential scanning calorimetry (DSC) measurements. Very high T g values afforded by the isosorbide substructure were measured (from 143 to 193 °C), which increase with furan ring content. Internally catalyzed transesterification reactions conferred fast dynamic exchanges (τ* = 300 s at 180 °C). Self-healing and chemical and mechanical recycling were also demonstrated. Finally, the degradability of the sugar-based polybenzoxazine vitrimers was demonstrated as well. The materials were highly stable in pH-neutral water, even at 80 °C for 60 days, but owing to the isosorbide structure, pronounced degradation was observed under acidic or alkaline conditions. In summary, isosorbide is a suitable building block for the design of degradable and 100% recyclable high-T g polybenzoxazine vitrimers.

Asymmetric di-benzoxazine monomers from naturally occurring phenolic compounds – cardanol and vanillin – were synthesized to obtain a processable and self-supported bio-thermoset with valuable properties. Such strategy constitutes an efficient and versatile route for the elaboration of biobased thermoset from a wide range of phenolic compounds derived from renewable resources.