Bio-based polyhydroxyamides (PHAs) are promising functional materials that have the potential to be utilized in various fields. However, the complex steps required for synthesizing high-performance PHAs limit their large-scale manufacture and further applications. To address this challenge, a novel and simple strategy was proposed for preparing strong PHAs with tunable adhesion, sensitive humidity response, and unique fluorescence properties by using bio-based monomers via melt polycondensation. These PHAs are thermally stable and possess tunable mechanical properties. The multiple hydrogen bonds endow PHAs with excellent adhesive properties. The overlapping shear strength was 24.6 MPa when using stainless steel plates. The humidity response of PHAs can be controlled by adjusting the water absorption content, and the hygroscopic-induced crystallization endows PHAs with excellent shape re-editing and shape memory properties. The presence of abundant amide bonds in PHAs promotes the formation of amide cluster-induced luminescence in these PHAs. The combination of sustainable raw materials and high-performance PHAs presents various opportunities for the development of new functional polyamides toward strong sustainable adhesives.
The synthesis of highly important α-hydroxycarboxylic acid anilides via copper-catalyzed chemoselective C–N coupling reactions of α-hydroxyamides and aryl halides is described. This highly selective N-arylation process demonstrates wide substrate scope, cost savings and easy operation. In addition, the chirality of l-3-phenyllactamide is preserved during the reaction.
Zhe Li,Zenghui Tan,Yajun Xu,Wei Wei,Xiaojie Li,Jingcheng Liu
Lignin with increased polyhydroxyl content (LOH) was prepared via a one-pot synthesis using enzymatically hydrolyzed lignin (EHL) as the raw material. The modified structure and hydroxyl content of LOH were analyzed using FT-IR, 1 H NMR, and 31 P NMR. LOH was blended with zinc oxide (ZnO), polyester resin and hydroxyl alkyl amide (HAA) to prepare polyester powder coatings. The anti-UV properties of the coating were significantly enhanced by the addition of LOH and ZnO. The coating exhibits exceptional adhesion, rating at level 0, and achieves a pencil hardness of 7H. The gel time for the coating is 195 s, and it has a 5-degree Celsius increase in melting temperature, which greatly enhances its storage stability. Considering a range of factors, the formula LOH7.5 % has been identified as the optimal composition. The results of this study demonstrate an easy approach to developing sustainable lignin-based powder coatings with excellent properties.
Diglycerol and dimer acid (DA) are used as precursors for the solvent- and catalyst-free synthesis of fully biobased non-isocyanate polyurethanes to replace toxic isocyanates and petroleum-based reactants. Linear polyhydroxy(amide-urethane)s (L-NIPHAUs) were synthesized via the melt aminolysis copolymerization between diglycerol dicarbonate (DGDC) and diamino-telechelicoligoamides (DAPAhs) from DA and hexamethylenediamine (HDA). By changing the DA/HDA molar ratios, the structures of DAPAhs and L-NIPHAUs were regulated in a simple and straightforward manner. Atomic force microscopy (AFM) and dynamic mechanical analysis (DMA) of the L-NIPHAUs reveal that the huge polarity difference between the hard segments (HSs) and soft segments (SSs) leads to nanophase separation. The N-amidohexylene-diglycerolbis(hydroxyurethane)-N′-amidohexylene and N-amido-hexylene-N′-amido segments form double HSs, while the bulky nonpolar DA residues serve as SSs. L-NIPHAUs also exhibit semicrystalline structures with good thermal stability evidenced by wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). They possess Tm ranging from 94 to 110 °C and tunable mechanical properties with a tensile strength of 7.3–12.1 MPa and strain at break of 311–858%. Introducing DA segments increases the hydrophobicity of L-NIPHAUs and the water contact angle and decreases the surface energy. L-NIPHAUs also show excellent solvent resistance in organic solvents, thanks to their intramolecular hydroxyurethane hydrogen bonding, three-dimensional inherent intermolecular hydrogen bonding networks, and the modification of bulky nonpolar DA SSs.
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