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.

Keywords

Polyester elastomers / citric acid / AgNWs / strain sensitivity / degradable

References

[1] Patel S,Zhao M.Wearable electronics for skin wound monitoring and healing.Soft Sci2022;2:9

[2] Chen J,Chang X.Recent progress in essential functions of soft electronic skin.Adv Funct Mater2021;31:2104686

[3] Zhu J,Zhang M.Recent progress in flexible tactile sensor systems: from design to application.Soft Sci2021;1:3.

[4] Vallem V,Ozturk M,Dickey MD.Energy harvesting and storage with soft and stretchable materials.Adv Mater2021;33:e2004832

[5] Yu J,Deng Y.Recent progress in pressure and temperature tactile sensors: principle, classification, integration and outlook.Soft Sci2021;1:6

[6] Gui Q,Wang Y.Soft electronics based on liquid conductors.Adv Electron Mater2021;7:2000780

[7] Wolf MP,Hunziker P.PDMS with designer functionalities-properties, modifications strategies, and applications.Progr Polym Sci2018;83:97-134

[8] Qi D,Tian G,Huang Y.Stretchable electronics based on PDMS substrates.Adv Mater2021;33:e2003155

[9] Zhang K,Chen J,Jiang B.Self-healing and stretchable PDMS-based bifunctional sensor enabled by synergistic dynamic interactions.Chem Eng J2021;412:128734

[10] Yang Y,He P,Sun J.Ti3C2Tx MXene-graphene composite films for wearable strain sensors featured with high sensitivity and large range of linear response.Nano Energy2019;66:104134

[11] Cai Y,Wang G.A flexible ultra-sensitive triboelectric tactile sensor of wrinkled PDMS/MXene composite films for E-skin.Nano Energy2021;81:105663

[12] Wei Q,Pan H.MXene-sponge based high-performance piezoresistive sensor for wearable biomonitoring and real-time tactile sensing.Small Methods2022;6:e2101051

[13] Zhou Y,Ren M.Significant stretchability enhancement of a crack-based strain sensor combined with high sensitivity and superior durability for motion monitoring.ACS Appl Mater Interfaces2019;11:7405-14

[14] Zhang Y,Liu Y.Ultra-stretchable monofilament flexible sensor with low hysteresis and linearity based on MWCNTs/Ecoflex composite materials.Macro Mater Eng2021;306:2100113

[15] Yue X,Gao J.Wearable hydroxylated MWCNTs/ecoflex composite strain sensor with high comprehensive performance based on electron irradiation.Compos Sci Technol2022;226:109537

[16] Wang Y,Someya T.Electrospun nanofiber-based soft electronics.NPG Asia Mater2021;13:22

[17] Cho KW,Hong YJ.Soft bioelectronics based on nanomaterials.Chem Rev2022;122:5068-143

[18] Lyu Q,Yin J,Cheng W.Soft wearable healthcare materials and devices.Adv Healthc Mater2021;10:e2100577

[19] Kim MG,Brand O.Nanofabrication for all-soft and high-density electronic devices based on liquid metal.Nat Commun2020;11:1002 PMCID:PMC7035367

[20] Peng S,Wu S.Conductive polymer nanocomposites for stretchable electronics: material selection, design, and applications.ACS Appl Mater Interfaces2021;13:43831-54

[21] Mclellan K,Leung SN.Recent progress in transparent conductors based on nanomaterials: advancements and challenges.Adv Mater Technol2020;5:1900939

[22] Wang C,Huang Z.Materials and structures toward soft electronics.Adv Mater2018;30:e1801368

[23] Chiong JA,Lin Y,Bao Z.Integrating emerging polymer chemistries for the advancement of recyclable, biodegradable, and biocompatible electronics.Adv Sci (Weinh)2021;8:e2101233 PMCID:PMC8292855

[24] Zhang Q,Xu Y,Wang Z.Bio-based polyesters: recent progress and future prospects.Progress in Polymer Science2021;120:101430

[25] Davenport Huyer L,Wang Y.One-pot synthesis of unsaturated polyester bioelastomer with controllable material curing for microscale designs.Adv Healthc Mater2019;8:e1900245

[26] Chen CJ,Tseng PJ.Low-mass liquid crystalline materials blended in recycled thermoplastic polyester elastomer for corrosion inhibitor application.Polymers (Basel)2021;13:3188 PMCID:PMC8472966

[27] Satti SM.Polyester-based biodegradable plastics: an approach towards sustainable development.Lett Appl Microbiol2020;70:413-30

[28] Tang S,Wang R.Current trends in bio-based elastomer materials.SusMat2022;2:2-33

[29] Siehr A,Callaway T,Siegel RA.Implantable and degradable thermoplastic elastomer.ACS Biomater Sci Eng2021;7:5598-610

[30] De Hoe GX,Tiegs BJ.Sustainable polyester elastomers from lactones: synthesis, properties, and enzymatic hydrolyzability.J Am Chem Soc2018;140:963-73

[31] Wang D,Wang Z,Guo B.A bio-based, robust and recyclable thermoset polyester elastomer by using an inverse vulcanised polysulfide as a crosslinker.Polym Chem2022;13:485-91

[32] Wei T,Kang H.Tough Bio-based elastomer nanocomposites with high performance for engineering applications.Adv Eng Mater2012;14:112-8

[33] Kang H,Xue J.Preparation and characterization of high strength and noncytotoxic bioelastomers containing isosorbide.RSC Adv2014;4:19462

[34] Gao Y,Zhang L.Synthesis of bio-based polyester elastomers and evaluation of their in vivo biocompatibility and biodegradability as biomedical materials.Biomater Sci2022;10:3924-34

[35] Li B,Stewart IE,Wiley BJ.Synthesis and purification of silver nanowires to make conducting films with a transmittance of 99%.Nano Lett2015;15:6722-6

[36] Zhou H,Jin X.Intrinsically adhesive, highly sensitive and temperature tolerant flexible sensors based on double network organohydrogels.Chem Eng J2021;413:127544

[37] Zhou H,Zheng B.From glutinous-rice-inspired adhesive organohydrogels to flexible electronic devices toward wearable sensing, power supply, and energy storage.Adv Funct Materials2022;32:2108423

[38] Chang MH,Kim YS,Kim JY.Thin and long silver nanowires self-assembled in ionic liquids as a soft template: electrical and optical properties.Nanoscale Res Lett2014;9:330 PMCID:PMC4094401

[39] Peng Y,Yang C.Super tough and strong self-healing elastomers based on polyampholytes.J Mater Chem A2018;6:19066-74

[40] Yiming B,Han Z.A mechanically robust and versatile liquid-free ionic conductive elastomer.Adv Mater2021;33:e2006111

[41] Lu C,Wang J,Chu F.Integration of hydrogen bonding interaction and Schiff-base chemistry toward self-healing, anti-freezing, and conductive elastomer.Chem Eng J2021;425:130652

[42] Wang M,Jin X,Liu H.Multifunctional liquid-free ionic conductive elastomer fabricated by liquid metal induced polymerization.Adv Funct Mater2021;31:2101957

[43] Sun H,Zhai W.A highly sensitive and stretchable yarn strain sensor for human motion tracking utilizing a wrinkle-assisted crack structure.ACS Appl Mater Interfaces2019;11:36052-62

[44] Liu H,Du F,Li Z.Flexible and degradable paper-based strain sensor with low cost.ACS Sustain Chem Eng2017;5:10538-43