Cross-Linked Gold Nanoparticles on Polyethylene: Resistive Responses to Tensile Strain and Vapors

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• 作者：Natalia Olichwer ; Elisabeth W. Leib ; Annelie H. Halfar ; Alexey Petrov ; Tobias Vossmeyer
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2012
• 出版时间：November 28, 2012
• 年：2012
• 卷：4
• 期：11
• 页码：6151-6161
• 全文大小：605K
• 年卷期：v.4,no.11(November 28, 2012)
• ISSN：1944-8252

文摘

In this study, coatings of cross-linked gold nanoparticles (AuNPs) on flexible polyethylene (PE) substrates were prepared via layer-by-layer deposition and their application as strain gauges and chemiresistors was investigated. Special emphasis was placed on characterizing the influence of strain on the chemiresistive responses. The coatings were deposited using amine stabilized AuNPs (4 and 9 nm diameter) and 1,9-nonanedithiol (NDT) or pentaerythritol tetrakis(3-mercaptopropionate) (PTM) as cross-linkers. To prepare films with homogeneous optical appearance, it was necessary to treat the substrates with oxygen plasma directly before film assembly. SEM images revealed film thicknesses between 60 and 90 nm and a porous nanoscale morphology. All films showed ohmic I-V characteristics with conductivities ranging from 1 脳 10^鈥? to 1 脳 10^鈥? 惟^鈥? cm^鈥?, depending on the structure of the linker and the nanoparticle size. When up to 3% strain was induced their resistance increased linearly and reversibly (gauge factors: 20). A comparative SEM investigation indicated that the stress induced formation and extension of nanocracks are important components of the signal transduction mechanism. Further, all films responded with a reversible increase in resistance when dosed with toluene, 4-methyl-2-pentanone, 1-propanol or water vapor (concentrations: 50鈥?0 000 ppm). Films deposited onto high density PE substrates showed much faster response-recovery dynamics than films deposited onto low density PE. The chemical selectivity of the coatings was controlled by the chemical nature of the cross-linkers, with the highest sensitivities (1 脳 10^鈥? ppm^鈥?) measured with analytes of matching solubility. The response isotherms of all film/vapor pairs could be fitted using a Langmuir鈥揌enry model suggesting selective and bulk sorption. Under tensile stress (1% strain) all chemiresistors showed a reversible increase in their response amplitudes (30%), regardless of the analytes鈥?permittivity. Taking into consideration the thermally activated tunneling model for charge transport, this behavior was assigned to stress induced formation of nanocracks, which enhance the films鈥?ability to swell in lateral direction during analyte sorption.

Keywords:

gold; nanoparticle; film; coating; polyethylene; chemiresistor; rain+gauge&qsSearchArea=searchText">strain gauge