Effect of glycerol on the mechanical and temperature-sensing properties of pectin films

Abstract

Temperature-sensitive films embedded in electronic skins (e-skins) can provide temperature feedback to robots, high-tech prostheses, and wearable devices for health care monitoring. Pectin-based films have shown a temperature response at least two orders of magnitude higher than previously reported temperature-sensing materials. However, they are not easily stretchable and tearable, which limit their applications as e-skins that require repetitive bending and mechanical stresses. Here, we show how the addition of glycerol as a plasticizer in the fabrication of pectin-based films improves their mechanical properties. We report how the enhancement of the mechanical performance is accompanied by a decrease in the temperature responsivity. Through thermogravimetric analysis, we show that this reduction in responsivity can be associated with water retention due to the addition of the plasticizer. The link between the water content and the temperature response demonstrates that a dehydrated status of pectin is crucial to record its high temperature responsivity. Combining electrical and thermal characterization with the tensile strength test, we estimate the optimal concentration of glycerol for improving the mechanical properties without compromising the temperature response of the pectin films.

Optimization of citron peel pectin and glycerol concentration in the production of edible film using response surface methodology

“…The ANOVA analysis showed that elongation at break is significantly (P < 0.05) affected by the pectin and glycerol concentrations in all the studied terms ( Table 3 ). The elongation at break results of the pectin film agree with the finding reported by a previous study [ 35 ] that the effect of glycerol on the mechanical properties of pectin film. Sartori [ 36 ] suggested the increase in elongation at break is due to the increased polymer chain mobility in the presence of glycerol as pectin concentration increased the elongation of films enhanced and decreased at a high level of pectin.…”

Flexible biomimetic block copolymer composite for temperature and long-wave infrared sensing

“…Under these conditions, conduction through water channels dominates the transport, suppressing the effect of ions, which is mainly responsible for the large temperature-dependent impedance changes. As the film is dried, removing unbound water from the chain, the response increases markedly, indicating the growing portion of Ca 2+ -mediated transport ( 25 ). However, further dehydration results in a decreased response due to loss of conduction paths.…”

“…Recent investigations of plant cell wall components reported that pectin, a structurally and functionally complex acid-rich polysaccharide (22), has a remarkable response to temperature (23)(24)(25). Pectin consists mostly of repeating units of D-galacturonic acid (Fig.…”

Mechanical and Thermal Properties of Bioplastic Film Obtained From Orange Peel

“…With the increase in glycerol, pectinglycerol interactions increase, which favors the availability of hydrophilic regions along the main chain of pectin, causing an increase in hydrophilicity and mobility of the chains. This triggers more water molecules to be linked to the interior of the polysaccharide matrix, promoting its plasticizing effect (Costanza et al, 2019). As shown below in the thermogravimetric analysis, the water content in the bioplastic lms increased with the glycerol content.…”

“…As can be seen, the rst presents a shift to the left, while the second is within the common interval of decomposition. This degradation behavior may be due to structural differences within the polymeric matrix, caused by the heterogeneous distribution of the hydrogen bonds of the pectin-pectin interactions, which may bene t from the heterogeneous dispersion of the glycerol molecules, possibly caused by the high brous content of the sample (Costanza et al, 2019;Darni et al, 2017).…”