Effects of Immobilized Ionic Liquid on Properties of Biodegradable Polycaprolactone/LDH Nanocomposites Prepared by In Situ Polymerization and Melt-Blending Techniques

Abstract

The high capacity of calcinated layered double hydroxides (LDH) to immobilize various active molecules together with their inherent gas/vapor impermeability make these nanoparticles highly promising to be applied as nanofillers for biodegradable polyester packaging. Herein, trihexyl(tetradecyl)phosphonium decanoate ionic liquid (IL) was immobilized on the surface of calcinated LDH. Thus, the synthesized nanoparticles were used for the preparation of polycaprolactone (PCL)/LDH nanocomposites. Two different methods of nanocomposite preparation were used and compared: microwave-assisted in situ ring opening polymerization (ROP) of ε-caprolactone (εCL) and melt-blending. The in situ ROP of εCL in the presence of LDH nanoparticles with the immobilized IL led to homogenous nanofiller dispersion in the PCL matrix promoting formation of large PCL crystallites, which resulted in the improved mechanical, thermal and gas/water vapor barrier properties of the final nanocomposite. The surface-bonded IL thus acted as nanofiller surfactant, compatibilizer, as well as thermal stabilizer of the PCL/LDH nanocomposites. Contrary to that, the melt-blending caused a partial degradation of the immobilized IL and led to the production of PCL nanocomposites with a heterogenous nanofiller dispersion having inferior mechanical and gas/water vapor barrier properties.

A Brief Review on the Influence of Ionic Liquids on the Mechanical, Thermal, and Chemical Properties of Biodegradable Polymer Composites

“…Meanwhile, the LDH/PCL composite films were fabricated by employing [P6, 6,6,14][C9H19CO2] ionic liquid as a modifier [26]. The mechanical, thermal, and chemical properties of the composite films and their components were characterized by using a universal testing machine, thermal gravimetric analyzer, differential scanning calorimeter, Fourier transform infrared spectrometer, and X-ray diffractometer.…”

“…Meanwhile, the LDH/PCL composite films were fabri [P6, 6,6,14][C9H19CO2] ionic liquid as a modifier [26]. The mechanical, properties of the composite films and their components were ch universal testing machine, thermal gravimetric analyzer, differen ter, Fourier transform infrared spectrometer, and X-ray diffracto properties, such as the tensile strength, elongation at break, and Y composite film containing [P6, 6,6,14][C9H19CO2]-modified LDH, inc such as the infrared absorption bands of the C=O stretching vibrations, of the composite fibers, shifted to lower wavenumber regions in comparison to the C=O stretching vibration of the neat PLA.…”

“…Thus, it can be deduced that the employment of [P6, 6,6,14][Cl] ionic liquid prohe MMT/PBS composite with a high tensile strength and high glass transition teme, and its components have a good interaction. eanwhile, the LDH/PCL composite films were fabricated by employing [C9H19CO2] ionic liquid as a modifier [26]. The mechanical, thermal, and chemical ties of the composite films and their components were characterized by using a al testing machine, thermal gravimetric analyzer, differential scanning calorimerier transform infrared spectrometer, and X-ray diffractometer.…”

“…Furthermore, the thermal properties, such as the decomposition temperature of the composite film containing [P 6,6,6,14 ][C 9 H 19 CO 2 ]-modified LDH increased by up to 4.7% in comparison to the neat PCL film. This was due to the improvement in the thermal stability of the composite film, which correlated with the formation of much larger PCL crystallites in the composite film [ 26 ]. In addition, the melting temperature of the composite film increased by up to 6.2% compared to the neat PCL film.…”

“…This is due to their biodegradability, renewability, economy, and availability [15]. On the other hand, inorganic materials, such as multiwalled carbon nanotubes [16][17][18][19] graphene oxide [20,21] graphene [22,23] layered double hydroxide [24][25][26][27] montmorillonite [28,29] ammonium polyphosphate [30] and zinc oxide [31] have been used as inorganic fillers. Figure 1 shows the chemical structures of cellulose, starch, chitin, multiwalled carbon nanotubes, graphene oxide, and ammonium polyphosphate.…”