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The development of green, sustainable, biomass-based adhesives as alternatives to petroleum-based adhesives has emerged as a critical strategy in addressing environmental pollution and resource depletion. Cellulose represents an abundant and sustainable biomass material. However, the high density of hydroxyl groups along the cellulose molecular chains results in strong hydrophilicity, which limits its application in the adhesive sector. Crafting high water-resistance adhesives from cellulose is a task that is both promising and challenging. In this study, cellulose was modified to generate tosyl cellulose (TC), which was subsequently crosslinked with polyamines of varying degrees of branching. The effects of polyamine branching and the mass ratio of polyamine to tosyl cellulose on the performance of the TC-PA adhesive were investigated. The structure of the TC-PA adhesive was characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The results indicated successful synthesis of the TC-PA adhesive, with the reaction between TC and polyamines leading to the formation of macromolecules. The introduction of TC significantly lowered the curing temperature of the polyamines. Consequently, this novel cellulose-based adhesive demonstrates excellent water resistance and potential for broad applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The adsorption potential of activated carbon (AC) is determined to a large extent by an interplay between its surface functional groups and target pollutants like volatile organic compounds (VOCs). Herein, we present a new approach to improve such property through the creation of nanodisk-like material by modifying the surface and morphology of AC with branched polyamine (BPA). The formulated AC-BPA possesses large number of surface functional moieties (e.g., amine, –COOH, –OH, and Cl−) to facilitate physical, chemical, and reactive adsorption to tackle a common air pollutant such as formaldehyde (FA). Despite its reduction in surface area (relative to AC), AC-BPA was demonstrated to have a significantly large potential for reactive adsorption and catalytic oxidation (RACO) against FA with high adsorption capacity (82.3 mg g−1) and partition coefficient (PC = of 0.64 mol kg−1 Pa−1) under dry condition. Interestingly, a noticeable enhancement in its performance is attained by the presence of moisture (e.g., 100 % RH) as evidenced by adsorption capacity of 144.3 mg g−1 (PC of 1.25 mol kg−1 Pa−1). This can be attributed to its rich heteroatom content (e.g., COO− and Cl−), possibly inducing partial ionization of water molecules and generating secondary active sites for FA adsorption. In-situ diffuse reflectance infrared Fourier-transform spectroscopy revealed that AC-BPA catalyzed the chemical transformation of FA into methylol adducts, H 2 O, and CO 2. These findings indicate that FA adsorption is primarily influenced by surface functional groups rather than by surface area. This study is expected to pave the way for designing metal-free high-performance RACO materials against FA under ambient conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing formaldehyde-free and excellent water resistance has constantly been at the center of attention of wood adhesives. In addition to enhancing the adhesive itself, the modification of wood interface can also improve its bonding strength and water resistance. In this study, aqueous solutions of NaIO 4 and NaClO 2 have been sprayed onto the surface of poplar veneer evenly. An activated wood interface equipped with -CHO and -COOH was prepared. Traditional polyurethane adhesives are primarily two-component, with excessive manufacturing cost, complicated production and use procedures. In this study, a single component high branched polyurethane adhesive (GI) was synthesized via a A 2 +B 3 oligomerization method by using glycerol and isophorone diisocyanate (IPDI). Using branched polyamine (PA 4 N) as a modifier, GI was modified to GI-PA 4 N , which was used as an adhesive and then hot pressed with the activated wood to make three-layer plywood. The bonding interface was equipped with urethane bonds, urea-based chemical bonds, amide bonds, Schiff bonds and hydrogen bond, which considerably enhanced the stability and water resistance of the bonding interface. FT-IR and XPS confirmed the existence of -CHO and -COOH at the interface of the activated wood, and characterized the synthesis mechanism and bonding mechanism of GI-PA 4 N. The results indicated that when the mass ratio of polyurethane to polyamine was 4:1, the overall performance of the adhesive was the best. The dry bonding strength increased from 1.92 MPa to 3.63 MPa, and the wet bonding strength increased from 1.77 MPa to 3.13 MPa, much higher than the minimum requirement of GB/T 17657–2013 (0.7 MPa). A formaldehyde-free, high-performance plywood with excellent water resistance was successfully prepared using wood interfacial activation and branched polyamine modification. [Display omitted] • An activated wood interface equipped with -CHO and -COOH was prepared. • A highly branched GI-PA 4 N adhesive with cross-linked network was synthesized. • The dry and wet bonding strength increased by 78% and 23%, respectively. • This work offers an effective method for producing high-performance materials. [ABSTRACT FROM AUTHOR]

Abstract: The molecular topology of amine curing agents is expected to greatly affect the curing reaction and properties of the epoxy resins, yet the exact influence still remains little understood. Herein we find out two representative aliphatic amines: linear propanediamine (PDA) and branched N,N,N′,N′-tetra(3-aminopropyl)-1,3-propanediamine (TAPA), and use them to cure diglycidyl ether of bisphenol A (DGEBA). The curing reaction, dynamic mechanical properties, and thermal stability of DGEBA/PDA and DGEBA/TAPA are systematically investigated and compared. Differential scanning calorimetry (DSC) confirms TAPA and PDA have very close reactivity much higher than that of commercial Jeffamine T-403 with the branched molecular structure. The curing kinetic analysis shows TAPA causes the higher isothermal conversion at the lower temperature (e.g., 40°C), the autocatalysis and diffusion-associated kinetics feature the isothermal reactions, and the extended Kamal model turns out to be able to well predict the curing rate. Then, the isoconversional analysis with the Vyazovkin methods demonstrates compared to PDA, TAPA leads to the lower effective activation energy at the very beginning due to its catalytic tertiary amino groups, but the reversed trend emerges in the deep-conversion stage, especially, in the glass-transition regime, owing to its flexible aliphatic molecular chains. Furthermore, the isothermal conversion at the higher temperatures is predicted from the nonisothermal experiments. Finally, dynamic mechanical analysis (DMA) shows cured DGEBA/TAPA exhibits the higher glass- and β-relaxation temperatures and crosslink density than DGEBA/PDA, and thermogravimetric analysis (TGA) reveals TAPA-cured epoxy has the excellent thermal stability with the higher char yield. [Copyright &y& Elsevier]

A pentavalent branched-chain polyamine, N 4 -bis(aminopropyl)spermidine 3(3)(3)4, is a unique polycation found in the hyperthermophilic archaeon Thermococcus kodakarensis, which grows at temperatures between 60 and 100 °C. We studied the effects of this branched-chain polyamine on DNA structure at different temperatures up to 80 °C. Atomic force microscopic observation revealed that 3(3)(3)4 induces a mesh-like structure on a large DNA (166 kbp) at 24 °C. With an increase in temperature, DNA molecules tend to unwind, and multiple nano-loops with a diameter of 10-50 nm are generated along the DNA strand at 80 °C. These results were compared to those obtained with linear-chain polyamines, homocaldopentamine 3334 and spermidine, the former of which is a structural isomer of 3(3)(3)4. These specific effects are expected to neatly concern with its role on high-temperature preference in hyperthermophiles., (© 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)