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

Nanocomposites of functionalized carbon nanotubes (CNTsf) used as a reinforcement agent, and a polyurethane (PU), as a polymeric matrix were synthesized via in situ polymerization. Carbon nanotubes (CNTs) were chemically functionalized using four different chemical treatments to obtain (1) oxidized CNTs (CNTsOH, COOH), (2) CNTs containing aliphatic amine groups (CNTset diam), (3) CNTs attached to an aromatic amine group (CNTs4AB), and (4) CNTs containing a combination of aromatic amine, hydroxyl, and carboxyl functional groups (CNTs4AB, OH, COOH). The nanocomposites (prepared using 0.25, 0.5 or 1.0 wt % CNTsf) were synthesized by two processes: (1) one-step using a PU made from PCL-diol (alpha-omega-telechelic polyester diol) obtained by biocatalysis from epsilon-caprolactone (epsilon-CL) and diethylene glycol (DEG) and 4,4 '-methylenebis (cyclohexyl isocyanate) (H12MDI) in stoichiometric amounts, (2) two-step process (chain extended PU) using hexamethylene diamine (HMDA). Depending on the chemical route used to synthesized the nanocomposites, CNTsf form, in some cases, covalent bonds and hydrogen bonding with the soft and/or hard segments of the PU matrix. Also, the presence of CNTsf improves the thermal stability of the nanocomposites and some of their mechanical properties, compared to the pure PU properties. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47319.