Preparation and characterization of nanocomposites made from chemoenzymatically prepared polyester urethanes and functionalized multiwalled carbon nanotubes

Abstract

Multiwalled carbon nanotubes (MWNTs) were functionalized with four different functional groups and used as nanofillers to reinforce biodegradable polyurethanes (PU), in an effort to explore their effect on the thermal and mechanical properties of the obtained nanocomposites. The PU were synthesized via one step process, by the reaction between a αω‐telechelic polyester diol (obtained by biocatalysis from ε‐caprolactone and diethylene glycol), and hexamethylene diisocyanate. The MWNTs were synthesized via a chemical vapor deposition process using ethanol as a carbon source. Functionalization with (i) hydroxyl and carboxyl groups OH‐COOH; (ii) aliphatic amine: ethylene diamine; (iii) aromatic amine: 4‐amine benzoic acid (4AB); or (iv) aromatic amine and carboxyl acid: 4‐amine benzoic acid, hidroxyl, and carboxyl groups (4AB‐OH‐COOH) were achieved. Nanocomposites were obtained by adding functionalized CNTs during the polymerization reaction between αω‐telechelic diol and the isocyanate. Three different percentages of functionalized CNTs were tried: (a) 0.25; (b) 0.5; or (c) 1%wt. The structural, morphological, and mechanical features of MWNTs/PU nanocomposites were studied by FT‐IR, differential scanning calorimetry, field emission scanning electron microscopy, TGA, wide angle X‐ray diffraction, solid‐state NMR, and mechanical properties. A better interfacial adhesion was observed for nanocomposites containing 0.5% wt of filler, compared to the neat PU. POLYM. COMPOS., 39:E697–E709, 2018. © 2016 Society of Plastics Engineers

Synthesis, characterization, and mechanical performance of various functionalized carbon nanotubes‐polyurethanes nanocomposites

“…On the contrary, for both types of nanocomposites, unidirectional tensile tests and TGA results show that CNTs f improves some of their mechanical properties (highlighting the toughness of nanocomposites prepared by two‐step method) and its thermal stability. Interfacial adhesion, thermal, and mechanical properties of the nanocomposites studied were a function of the amount of CNTs added, in contrast to the behavior observed for the nanocomposites studied in our previous report, where the effect of the amount of CNTs on these properties was not important . In general, mechanical properties of nanocomposites prepared by two‐step show better properties than those observed in nanocomposites prepared by one‐step.…”

“…On the other hand, for nanocomposites prepared by a two‐step approach, CNTs OH, COOH , CNTs et diam , or CNTs 4AB are also covalently attached to some PU chains, also via a chemical reaction where terminal isocyanate groups participated. In contrast, in our previous study on nanocomposites, it was not found evidence of formation of covalent bonds between the chemical groups of PU matrix and functionalized CNTs …”

“…Differences in thermal and mechanical properties of synthesized nanocomposites are discussed in terms of the type of functionalized CNTs used. Striking differences are observed for the nanocomposites hereby obtained, compared to those previously reported by our group …”

“…We recently reported the synthesis and characterization of nanocomposites obtained from linear polyester urethanes obtained by a one‐step procedure. Polyester‐urethanes were prepared using hexamethylene diisocyanate and a PCL‐diol . In this article, a novel approach is tried: the effect of a two‐steps procedure is contrasted with the properties obtained using a one‐step approach.…”

“…Synthesis of PU was made by a one‐step process. Obtained nanocomposites were tough plastics with elastomeric properties, showing high thermal stability and degradability under alkaline conditions . These materials are being used to prepare thin porous membranes using the phase inversion method .…”