Nanotechnology measurements of the Young's modulus of polymeric materials

Making use of atomic force microscopy (AFM) —known as the state-of-the-art technology for handling matter on an atomic and molecular scale—, this paper describes the use of a nanotechnology technique for characterizing properties of polymeric materials. AFM measurement on two materials (polyamide and polystyrene) allowed to compare the performance of two distinct multi-asperity adhesion models based on the JKR (Johnson-Kendall-Robert) and DMT (Derajaguin- Muller-Toporov) theories, when assessing the Young’s Modulus (modulus of elasticity) of the investigated materials. Experimental results confirm that the JKR model processed through a MatLab algorithm produces more reliable results of the Young’s Modulus than the DMT model built-in in the AFM software

Sulfated and carboxylated nanocellulose for Co+2 adsorption

Regarding metals adsorption from aqueous solutions, nanocellulose emerges as a potential material, due to the many functionalization possibilities and enhanced surface contact area (nanostructured nature). In the present work, sulfated and carboxylated nanocellulose samples were obtained through sulfuric acid hydrolysis (S-CNC) and oxidation by TEMPO (CNF). The obtained nanofibers were characterized through multiple techniques, which XRD data indicated the presence of a-cellulose crystals, with crystallinity indexes equal to 72.3% (S-CNC) and 69.3% (CNF). Expressive morphological differences were revealed, whiskers particles for S-CNC, and elongated nanofibrils for CNF, with average thickness of 9.99 and 5.61 nm, respectively. The desired functionalization with carboxylate groups was evidenced based on FTIR data (CNF). A significant and homogeneous presence of sulfur was evidenced through SEM/EDS (S-CNC). The synthesized nanofibers were next applied to cobalt (Coþ2 ) adsorption from aqueous solutions at room temperature. On both cases, expressive maximum cobalt recoveries have been achieved, 90% (CNF) and 87% (S-CNC), for contact times higher than 30 and 45 min, respectively. The adsorptive capacities evaluated through ICP-OES from liquid phase data (87 mg g 1 S-CNC; 90 mg g 1 CNF) were both significantly higher than the values determined through LA-ICP-MS (10.5 mg Co g 1 S- CNC; 31.5 mg Co g 1 CNF)

Aerobic oxidation of 5-hydroxymethylfurfural to 5-hydroxymethyl-2-furancarboxylic acid and its derivatives by heterogeneous NHC-catalysis

The application of the oxidative system composed of a heterogeneous triazolium pre-catalyst, iron(II) phthalocyanine and air is described for the selective conversion of 5-hydroxymethylfurfural (HMF) into the added-value 5-hydroxymethyl-2-furancarboxylic acid (HMFCA). The disclosed one-pot two-step procedure involved sequential oxidative esterifications of HMF to afford a polyester oligomer having hydroxyl and carboxyl terminal groups (Mw = 389–1258), which in turn was hydrolyzed by a supported base (Ambersep 900 OH) to yield HMFCA in 87% overall yield. The same strategy was adopted for the effective synthesis of ester and amide derivatives of HMFCA by nucleophilic depolymerization of the oli- gomeric intermediate with methanol and butylamine, respectively. The utilization of the disclosed oxi- dative system for the direct conversion of HMF and furfural into their corresponding ester, amide, and thioester derivatives is also reported

One‐Pot Synthesis of Carboxymethylcellulose‐Templated Copper‐NPs for Heterocatalytic Huisgen‐Click Reactions on Lignocellulosic Bamboo Slices

We demonstrated the one-pot synthesis of copper nanoparticles (mainly as Cu0; CuNPs) mediated by carboxymethylcellulose in water and their heterocatalytic activity when supported on lignocellulosic bamboo slices (CuNPs-BSs). The real-time monitoring of CuNPs formation was performed by time-domain NMR under different temperatures and concentrations of copper precursor. Several 1,4-disubstituted 1,2,3-triazoles were synthesized in organic and aqueous solution at 70 °C. The unprecedented CuNPs-BSs were reused several times with minimal leaching (1.14 ppm) of the copper nanocatalyst

Fabrication of Lignocellulose-Based Microreactors: Copper- Functionalized Bamboo for Continuous-Flow CuAAC Click Reactions

The fabrication of a new copper-functionalized lignocellulosic microreactor (Cu-LμR) from bamboo culms is herein described together with its operation to perform a copper(I)-catalyzed 1,3-dipolar cycloaddition between azide and terminal alkyne (CuAAC). The bio-microfluidic device showed an easy prototyping and fast functionalization with copper ions. All reactions were carried out in flow regime with aqueous-methanol solvent and minimal leaching of copper, yielding a series of model 1,4-disubstitued triazole derivatives with good efficiency in a low-resource setting