Citric acid-based degradable polyester elastomers coated with silver nanowires for sustainable soft sensors

Abstract

Although soft electronic materials are of significant importance for flexible electronic devices, most of them are derived from commercial polymer elastomers, such as polydimethylsiloxane, polyurethane and Ecoflex. In this work, citric acid-based degradable polyester elastomers are prepared by a melt polycondensation process, utilizing citric acid, 1,8-octanediol and poly(ethylene glycol) (PEG) as monomers. Furthermore, poly(1,8-octanediol citrate acid) (POC)-PEG/silver nanowire (AgNW) conductive polyester elastomers (CPEs) are prepared by introducing a AgNW layer on the surface of the POC-PEG films. Scanning electron microscopy images reveal that the thickness of the AgNW layer is on the scale of several micrometers and the AgNWs form a continuous conductive network. Upon mechanical stimuli, POC-PEG exhibits recoverable deformation and induces variation in the AgNW conductive network, resulting in a conversion of strain to detectable resistance. When tensile strain is applied, the POC-PEG/AgNW CPEs achieve a gauge factor of 231.6, a response range of 0%-50%, a low response time of 35 ms and high stability. Moreover, the POC-10PEG/AgNW CPE also responds to bending deformation with a gauge factor of 3667.5, a response range of 0%-8.4%, a low response time of 62 ms and high stability. On the basis of strain sensitivity, wireless sensors are further assembled by integrating the POC-PEG/AgNW CPEs into a Bluetooth signal transmission system. Various human motions and physiological activities are successfully monitored using the wireless sensors. The results demonstrate that degradable citric acid-based polyester elastomers/AgNW CPEs are promising materials for next-generation sustainable and flexible electronic devices.

Transient Flexible Multimodal Sensors Based on Degradable Fibrous Nanocomposite Mats for Monitoring Strain, Temperature, and Humidity

“…For PBT/POC-PEG75, the elongation at break and tensile strength were 160% and 2.9 MPa, respectively. Compared with the previous POC-PEG elastomers, which exhibited a tensile strength of 0.6 MPa, 30 the strength of PBT/ POC-PEG mats was obviously increased.…”

“…Magnesium nitrate [Mg(NO 3 ) 2 , AR], potassium carbonate [(K 2 CO 3 ), AR], sodium chloride (NaCl, AR), sodium hydroxide (NaOH, AR), and dichloromethane (DCM, AR) were purchased from Tianjin Damao Chemical Reagent Factory. POC-PEG prepolymers 30 and AgNWs 32 were prepared according to previously reported methods. Deionized water was homemade and used throughout the whole experiment.…”

“…PBT is a typical degradable polymer, and the degradability of the POC-PEG component has been demonstrated in previous work. 30 It can be expected that the flexible multimodal sensors assembled from AgNWs/PBT/ POC-PEG mats will also exhibit degradability. The flexible multimodal sensors can be used as transient sensors, and the deserted sensors could be degraded.…”

“…The degradability occurs under alkaline aqueous conditions with a mass loss of 30% after 30 days. 29 In previous work, 30 citrate-based polyester elastomers (POC-PEGs) have been prepared and further functionalized with AgNWs. Flexible sensors assembled from POC-PEG−AgNWs composites exhibit excellent strain-sensing performances, and such sensors can be rapidly degraded.…”

Recent Developments in Synthesis, Properties, Applications and Recycling of Bio-Based Elastomers

“…Finally, it is essential to consider that other renewable resources such as polylactic acid (PLA) [ 92 ] and citric acid [ 97 ] are still undergoing investigation to be considered excellent components to produce polyester and polyether elastomers. Indeed, Nagarajan et al [ 92 ] evaluated the production of a thermoplastic copolyester elastomer using PLA and Hytrel, a commercial thermoplastic polyester elastomer, to produce a more environmentally friendly material based on the substitution of the bio-based Hytrel into several compositions with the PLA being the optimal the formulation with 70/30.…”