The aim of this work was to develop polylactic acid (PLA) based porous films with suitable properties to be used as sensors and absorbers. The formulation was designed to make the films porous, ductile, and conductive and characterized by surface functionalization. The phase inversion method was used to impart porosity to the polymer film. Polycaprolactone (PCL) and graphite, in the form of graphite nanoplatelets (GNP), were added to increase the elongation at break of the polymer matrix and to make the systems conductive, respectively. To optimize the formulation, the effect of polymer concentration in the initial solution on the viscosity, porosity, and morphology was investigated. FE-SEM measurements showed that the phase inversion method allowed limiting the aggregation of both PCL domains and GNP, whose flakes were found to adhere well to the polymer matrix and to have a nucleating effect, as evidenced by DSC measurements. A simple aminolysis reaction was performed using a diamine, i.e., ethylenediamine, to generate surface amino functionalities. In particular, the extent of functionalization as a function of reaction time was investigated by using FT-IR spectroscopic measurements. By combining these results with the stability of the polymer film, which tends to lose its structural integrity due to the erosion caused by the aminolysis reaction, the optimal contact time with the aqueous solution of ethylenediamine was found. Mechanical measurements showed that the presence of PCL increased the elongation at break of films by 3 times compared to neat PLA. Finally, the films developed starting from the optimized formulations based on PLA/PCL blends, containing GNP and surface functionalized, proved to be effective electrodes for the voltammetric determination of ascorbic acid. In addition, it is of utmost relevance that both amino functionalization and GNP conferred high capacity to the films to retain fluorescein, a model dye.
Multifunctional Porous Films Based on Polylactic Acid/Polycaprolactone Blend and Graphite Nanoplateles
Damonte G.;Spotorno R.;Monticelli O.
2022-01-01
Abstract
The aim of this work was to develop polylactic acid (PLA) based porous films with suitable properties to be used as sensors and absorbers. The formulation was designed to make the films porous, ductile, and conductive and characterized by surface functionalization. The phase inversion method was used to impart porosity to the polymer film. Polycaprolactone (PCL) and graphite, in the form of graphite nanoplatelets (GNP), were added to increase the elongation at break of the polymer matrix and to make the systems conductive, respectively. To optimize the formulation, the effect of polymer concentration in the initial solution on the viscosity, porosity, and morphology was investigated. FE-SEM measurements showed that the phase inversion method allowed limiting the aggregation of both PCL domains and GNP, whose flakes were found to adhere well to the polymer matrix and to have a nucleating effect, as evidenced by DSC measurements. A simple aminolysis reaction was performed using a diamine, i.e., ethylenediamine, to generate surface amino functionalities. In particular, the extent of functionalization as a function of reaction time was investigated by using FT-IR spectroscopic measurements. By combining these results with the stability of the polymer film, which tends to lose its structural integrity due to the erosion caused by the aminolysis reaction, the optimal contact time with the aqueous solution of ethylenediamine was found. Mechanical measurements showed that the presence of PCL increased the elongation at break of films by 3 times compared to neat PLA. Finally, the films developed starting from the optimized formulations based on PLA/PCL blends, containing GNP and surface functionalized, proved to be effective electrodes for the voltammetric determination of ascorbic acid. In addition, it is of utmost relevance that both amino functionalization and GNP conferred high capacity to the films to retain fluorescein, a model dye.
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