1. Evaluation of Polymeric Nanocomposites for the Detection of Toxic Gas Analytes
Kate Stewart and Alex Penlidis
Department of Chemical Engineering
University of Waterloo

2. Toxic Gas Analytes
There are numerous applications in which sensing gas analytes is important
Ethanol detection to reduce drinking and driving
Acetone detection as a disease indicator
Benzene and formaldehyde detection in air
In any application, target gases are present with other interferent gases

3. Sensing Characteristics
Sensitivity
Related to the detection limit of a sensor; the lower the detection limit, the more sensitive the sensor.
Selectivity
Ratio between the responses of target analyte to interferent analyte.
Operational Temperature
Temperature at which the sensor operates.
Response/Recovery Times
Time it takes to reach 90% of full signal/time it takes to return to 10% of the baseline.

4. Selecting Sensing Materials
Target Analyte
Functional Groups
Molecule Size
Application Constraints
Operational Temperature
Environmental Stability
Sensor Constraints
Type of Sensor
Potential Polymeric Sensing Materials
Resistive?
Conductive
Capacitive?
Dielectric
Mass-based?
Light weight
Add group(s)?
Dopants?
Metal or Metal oxide
Acids Tg
Chemically Stable?
Interferents?
Dominant Mechanisms
Polar?
H-bond?
Lewis acid/base?
Aromatic?
Bulky?
Polymer Modification
Dopants

5. Poly (2,5-dimethyl aniline) P25DMA
Amine group attracts polar molecules, especially molecules able to hydrogen bond
Two methyl side groups reduce the ability of P25DMA to pack closely
Doped with 5 metal oxide nanoparticles
CuO, Al2O3, ZnO, NiO, TiO2 N H
CH3

6. Characterization
X-ray Diffraction (XRD) to determine crystallinity of the polymer composites
Energy Dispersive X-ray (EDX) to determine composition of samples
Scanning Electron Microscopy (SEM) to look at the morphology of the polymer composites

7. Experimental Test System
Very Sensitive Gas Chromatograph with PDHID
MFC: Mass Flow Controller; PC: Pressure Controller; FM: Flow Meter

8. Polymeric Nanocomposite
P25DMA Doped with CuO
(c)
5 μm
(b)
1 μm
(d)
(a)
200 nm
Polymeric Nanocomposite
Weight Percent
P25DMA 5% CuO
0.16
P25DMA 10% CuO
0.07
P25DMA 20% CuO
0.11

9. P25DMA Doped with CuO

10. Polymeric Nanocomposite
P25DMA Doped with Al2O3
(a)
200 nm
1 μm
(c)
5 μm
(b)
(d)
Polymeric Nanocomposite
Weight Percent
P25DMA 5% Al2O3
0.61
P25DMA 10% Al2O3
0.57
P25DMA 20% Al2O3
0.49

11. P25DMA Doped with Al2O3 P25DMA P25DMA 5% Al2O3 P25DMA 10% Al2O3

12. Polymeric Nanocomposite
P25DMA Doped with ZnO
(a)
200 nm
1 μm
(c)
5 μm
(b)
(d)
100 nm
Polymeric Nanocomposite
Weight Percent
P25DMA 5% ZnO
0.34
P25DMA 10% ZnO
0.86
P25DMA 20% ZnO
46.89
1 μm

13. P25DMA Doped with ZnO

14. Polymeric Nanocomposite
P25DMA Doped with NiO
(b)
5 μm
(c)
1 μm
100 nm
(d)
(a)
Polymeric Nanocomposite
Weight Percent
P25DMA 5% NiO
5.58
P25DMA 10% NiO
8.11
P25DMA 20% NiO
19.14

15. P25DMA Doped with NiO

16. Polymeric Nanocomposite
P25DMA Doped with TiO2
(b)
5 μm
(c)
(d)
(a)
1 μm
Polymeric Nanocomposite
Weight Percent
P25DMA 5% TiO2
3.68
P25DMA 10% TiO2
12.37
P25DMA 20% TiO2
17.09

17. P25DMA Doped with TiO2

18. Summary of P25DMA Doped with 5% Metal Oxides

19. Sensor Array
Unknown

20. Gas Mixtures
Gas Mixture

21. Concluding Remarks Sensing mechanisms to choose sensing materials
Not all metal oxide nanoparticles can be fully incorporated into a polymer matrix
Metal oxide nanoparticles affect the morphology and sensing properties of a polymer composite
Selectivity can be improved by combining different partially selective sensing materials into an array
Able to separate 6 different gas analytes using 5 different sensing materials
Able to identify unknown gases

22. Thank you

23. References
Stewart, K. M E. and A. Penlidis. “Designing Polymeric Sensing Materials for the Detection of Ethanol” Macromolecular Symposia 360 (2016)
Stewart, K. M. E., W. T. Chen, R. R. Mansour, and A. Penlidis. “Doped Poly (2,5- dimethyl aniline) for the Detection of Ethanol” Journal of Applied Polymer Science 132 (2015)
Stewart, K. M. E., N. T. McManus, E. Abdel-Rahman, and A. Penlidis. “Doped Polyaniline for the Detection of Formaldehyde” Journal of Macromolecular Science, Part A 49, 1 (2012) 1-6.
Chen, W. T., K. M. E. Stewart, R. R. Mansour, and A. Penlidis. “Novel Undercoupled Radio-frequency (RF) Resonant Sensor for Gaseous Ethanol and Interferents Detection” Sensors and Actuators A 230 (2015)

25. Sensing Mechanisms Primary Mechanisms Secondary Mechanisms
Polarity and Hydrogen Bonding
Lewis Acid-Base
p-orbitals and π-stacking
Metal Coordination
van der Waals Forces
Steric Hindrance
Secondary Mechanisms
Swelling
Solvent Effects

26. Weight Percent of Metal Oxide Incorporated
Polymeric Nanocomposite
CuO
Al2O3
ZnO
NiO
TiO2
P25DMA 5% MOx
0.16
0.61
0.34
5.58
3.68
P25DMA 10% MOx
0.07
0.57
0.86
8.11
12.37
P25DMA 20% MOx
0.11
0.49
46.89
19.14
17.09

27. EDX and SEM Reproducibility
P25DMA 20% TiO2
Polymeric Nanocomposite
P25DMA
5% Al2O3
5% ZnO
5% TiO2
Replicate 1
0.61
0.34
3.68
Replicate 2
0.57
0.33
3.79
Replicate 3
0.72