Volatile Organic Compound Detection Using Nanostructured Copolymers

Abstract

Regioregular polythiophene-based conductive copolymers with highly crystalline nanostructures are shown to hold considerable promise as the active layer in volatile organic compound (VOC) chemresistor sensors. While the regioregular polythiophene polymer chain provides a charge conduction path, its chemical sensing selectivity and sensitivity can be altered either by incorporating a second polymer to form a block copolymer or by making a random copolymer of polythiophene with different alkyl side chains. The copolymers were exposed to a variety of VOC vapors, and the electrical conductivity of these copolymers increased or decreased depending upon the polymer composition and the specific analytes. Measurements were made at room temperature, and the responses were found to be fast and appeared to be completely reversible. Using various copolymers of polythiophene in a sensor array can provide much better discrimination to various analytes than existing solid state sensors. Our data strongly indicate that several sensing mechanisms are at play simultaneously, and we briefly discuss some of them.

Precisely Defined Heterogeneous Conducting Polymer Nanowire Arrays – Fabrication and Chemical Sensing Applications

“…[12,[21][22][23][24][25][26] In many cases, multiple CP sensors that have diversified chemical properties are needed so that we can obtain distinct responses that serve as ''fingerprints'' corresponding to different analytes. Our method is ideal for fabricating such multiple-nanowire sensor systems.…”

Processing Matters: In situ Fabrication of Conducting Polymer Microsensors Enables Ultralow‐Limit Gas Detection

“…Additionally, in situ fabricated polythiophene films exhibit a much higher conductance (ca. 14 S Á cm À1 in our study) than poly(alkyl-thiophene) and other polythiophene derivatives, [1][2][3] which also contributes to the increased VOC signal strength. Finally, the parallel alignment of Au microelectrodes and polythiophene micrometer-scale stripes greatly accelerates the sensing response, since the signals need a very short period of time to reach the electrodes.…”

“…Figure 5B and C demonstrates their ultralow detection limit and fast responses, respectively, towards ethanol vapor. In comparison with conventional conducting-polymer-based gas sensors that are produced via solution processing and have a detection limit of several or dozen ppm (10 À6 ) for VOCs, [2,3] the in situ fabricated polythiophene sensor exhibits a reduced detection limit for VOCs down to the ppb level (10 À9 ). In addition, the detection limit of our system is superior to currently commercially available metal oxide sensors (hundreds of ppb) and can be operated at room temperature, unlike ZnO or SnO 2 gas sensors which are usually operated above 200 8C.…”

A high purity approach to poly(3‐hexylthiophene) diblock copolymers

“…The combination of superior optoelectronic properties and enhanced solubility 1,2 for regioregular poly(3-hexylthiophene) (rr-P3HT) has enabled materials based on P3HT to be widely used for organic field-effect transistors, 3-5 chemical sensors, 6,7 and photovoltaic solar cells. [8][9][10][11] Significantly, the optoelectronic performance of rr-P3HT thin film has been shown to depend on molecular weight, 12 processing conditions, 10 and end group functionalities which places significant demands on developing synthetic approaches that do not lead to defects in the P3HT chain.…”