Article pubs.acs.org/IECR
Functionalized Polycyclic Aromatic Polymers for High Temperature Wireless Chemical Memory Threshold Sensors Brad Leonhardt,† Praveenkumar Pasupathy,‡ Tanuj Trivedi,‡ Sheng Zhang,‡ Dean P. Neikirk,‡ and John G. Ekerdt*,† †
McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States Microelectronics Research Center, University of Texas at Austin, Austin, Texas 78712, United States
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S Supporting Information *
ABSTRACT: A pair of new polymers, poly(di-t-butylacenaphthylene) (pTBAcN) and poly(dipropylacenaphthylene) (pPAcN), were made via Friedel−Crafts alkylation of polyacenaphthylene. These polymers exhibit thermal stability beyond 250 °C and solubility in excess of 25 wt % in aliphatic hydrocarbons. Films of pPAcN over 10 μm thick were successively applied to planar surfaces via brush coating. Chemical memory for a passive wire resonant sensor was utilized to detect aliphatic hydrocarbons in high temperature environments. The coated threshold sensor showed a lower, stable resonant frequency before and after exposure to water at 130 °C for 3 h and showed an increased triggered resonant frequency after aliphatic exposure, consistent with an uncoated sensor device.
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INTRODUCTION Small sensor devices that allow wireless communication of data are of interest for many applications.1 Radio-frequency identification (RFID) devices are broadly used for wireless communication of static data, from powered medical devices to passive tags used in retail locations. Applying this concept of a passive, unpowered tag that can communicate wirelessly with a reader has been shown by Pasupathy et al.2 This technique uses a passive wireless resonant (PWR) sensor with a polymer layer covering its sense region immediately above the surface of the device. With the polymer layer in place, the ambient environment is excluded (Figure 1). The reading will be static, measuring only the known electrical properties of the polymer film. This method imparts chemical memory by returning a different, triggered value when the polymer is dissolved by the environment as part of a chemical-memory threshold sensing (CMS) device.2
One challenging application for small, deployable CMS devices is the harsh environment of near-borehole fracture region of an oil well. The size limitations (10 μm thickness) provided satisfactory chemical memory in nonexposed samples. A shift of 9 MHz in resonant frequency was observed. The coating remains robust in high temperature inerts such as water at 130 °C. The threshold sensor successfully triggers when exposed to hexanes at room temperature, demonstrating a full chemical memory cycle. This demonstration of both a polymer and a complete PWR sensor suitable for a high temperature shows a way forward for developing a new array of chemical memory sensors, targeting the chemistry to the target molecule of interest. In addition, further enhancements of the chemical memory effect would help broaden the applicability of this simple, passive sensor.
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ASSOCIATED CONTENT
* Supporting Information S
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.iecr.6b04541. 1 H NMR pPAcN 2-propyl chloride, 13C NMR spectra, GPC data, TGA and DSC data, and sensor cycle repeats (PDF)
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AUTHOR INFORMATION
Corresponding Author
*Tel.: 1-512-471-4689; E-mail:
[email protected]. ORCID
Tanuj Trivedi: 0000-0001-5552-4766 John G. Ekerdt: 0000-0002-1788-5330 Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This work was partly supported by the Advanced Energy Consortium (http://www.beg.utexas.edu/aec/) and the NSF NNCI. AEC member companies include Repsol, Shell, and Total.
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REFERENCES
(1) Chawla, V.; Ha, D. S. An Overview of Passive RFID. IEEE Communications Magazine 2007, 45, 11−17. (2) Pasupathy, P.; Trivedi, T.; Leonhardt, B.; Zhang, S.; Ekerdt, J. G.; Neikirk, D. P. Miniature passive wireless Resonant platform for chemical memory based threshold sensing. IEEE Sens. J. 2017, 17, 1209−1210. (3) Pasupathy, P.; Munukutla, S.; Neikirk, D. P.; Wood, S. L. Versatile wireless sacrificial transducers for electronic structural surveillance sensors. 2009 IEEE Sensors 2009, 979−983. (4) Ong, K. G.; Grimes, C. A.; Robbins, C. L.; Singh, R. S. Design and application of a wireless, passive, resonant-circuit environmental monitoring sensor. Sens. Actuators, A 2001, 93, 33−43. D
DOI: 10.1021/acs.iecr.6b04541 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX
