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Renewable Vitrimer—A Novel Route Towards Reprocessable and Recyclable Thermosets from Biomass-Derived Building Block
Published in Anandhan Srinivasan, Selvakumar Murugesan, Arunjunai Raj Mahendran, Progress in Polymer Research for Biomedical, Energy and Specialty Applications, 2023
Arunjunai Raj Mahendran, Mohammed Khalifa, Günter Wuzella, Herfried Lammer
In another study, lignin-derived vanillin-based vitrimers have been synthesized by introducing imine covalent bonds into its structure and its reprocessing ability and reusability characteristics have been investigated. The polyschiff vitrimers film was prepared by dissolving dialdehyde in dichloromethane followed by the addition of diethylenetriamine and tris(2-aminoethyl)amine. The resultant mixture was prepared in the form of film through solution cast process to obtain polyschiff vitrimer. Tris(2-aminoethyl)amine cross-linker to diethylenetriamine ratio was tuned to achieve vitrimer with various degrees of cross-linking network. With the increase in diethylenetriamine ratio, the degree of cross-linking increased in poyimine films. As a result, Tg increased from 48°C to 64°C. Also, degradation temperature was in the range of 350 to 370°C, which is directly linked with the degree of the cross-linking network. Addition to this, tensile strength of the polyimine film was in the range of ~47 MPa to ~57 MPa.
Non-Isocyanate-Based Waterborne Polyurethanes
Published in Ram K. Gupta, Ajay Kumar Mishra, Eco-Friendly Waterborne Polyurethanes, 2022
The first NIPU hydrogels were obtained and characterized by Gennen et al. [35]. Polyhydroxyurethanes were obtained in bulk by the reaction of poly(ethylene glycol) dicyclic carbonate with tris(2-aminoethyl)amine (TAEA) and selected diamine (m-xylylenediamine (mXDA), 1,8-diaminooctane (ODA) or 2,2′-(ethylenedioxy)diethylamine (EDDA)). The formulation was mixed at 60°C for 10 min and then cured at the same temperature for 24 h. Obtained PHUs (after removing unreacted monomers) were immersed in water for 168 h to prepare hydrogels. Mechanical and swelling properties of prepared PHU hydrogels are affected by the crosslinking ratio, which depends on the amount of TAEA in the monomers formulation (Table 24.6). It was also proved that hydrogels can be successfully reinforced by the incorporation of nanoclay Cloisite 30B (in the amount from 1 to 15 wt.%) into the monomer formulation before polymerization. An increasing amount of nanofiller resulted in increasing tensile properties and decreasing equilibrium water content and absorption.
Self-assembled Peptide Nanostructures and Their Applications
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Ghosh et al. have reported a short tetrapeptide PWWP (derived from an anti-microbial peptide indolicdin), which upon self-assembly formed vesicular structure (Figure 2.16) (Ghosh et al. 2007b). The same group also designed a tripodal dipeptide derivative, in which tris(2-aminoethyl)amine(tren) was used as the scaffold for the conjugation of three ditryptophan dipeptide units. The synthetic triskelion ditryptophan conjugate showed rapid self-organization into spherical nanostructures upon incubation in methanol/water mixture at 37°C for 7 days (Ghosh et al. 2007a). The molecular modeling structures suggested that the indole aromatic ring-induced π–π stacking played a crucial role in the self-assembly process.
Mechanistic insight on the water exchange mechanism of [Zn(tren)H2O]2+ and related complexes from a DFT study
Published in Journal of Coordination Chemistry, 2022
Basam M. Alzoubi, Dušan Ćoćić, Ralph Puchta, Rudi Van Eldik
Zinc(II) plays an important role in bioinorganic systems and is widely used in intracellular studies [1, 2]. The concentration of Zn2+in vivo is in the range from 10−9 M in the cytoplasm to 10−2 M in some vesicles [3]. A large number of enzymes and proteins contain divalent zinc [4]. The hydrolytic zinc enzymes (e.g. alkaline phosphatase (AP)) use external water molecules to react with electrophilic substrates as nucleophiles [5, 6] and form tetrahedral coordination structures [7]. Tripodal amine ligands such as tris(2-aminoethyl)amine (tren) [8] contain four N donor atoms and form trigonal bipyramidal configurations with an additional water molecule bound to the Zn(II) center [5, 9]. The zinc complex [Zn(tren)H2O]2+ is a structural model for the binding mode of coordinated water-like substrates in the active site of zinc enzymes [5]. The ligand tren offers the possibility to tailor steric and electronic properties by substituting the equatorial N-atoms [10].