Interfacial nanofibril composite for selective alkane vapor detection

1. A nanofiber composite sensor for detecting alkanes comprising a network of contacting nanofibers having multiple contact points each forming an interfiber interface of interdigitated alkyl chains, wherein the alkanes are adsorbed at the interfiber interface to increase an interfiber distance between first and second nanofibers and decrease charge transfer efficiency.

2. The composite sensor of claim 1 , wherein the alkanes are in vapor or liquid phase.

3. The composite sensor of claim 1 , wherein the interdigitated alkyl chains comprise at least one hydrophobic branched or straight alkyl chain (C n H 2n+1 or O—C n H 2n+1 ), wherein n=1-30.

4. The composite sensor of claim 1 , wherein the first nanofiber is a donor nanofiber formed of a donor molecule and the second nanofiber is an acceptor nanofiber formed of an acceptor molecule with a photoinduced charge transfer process between them to provide a homogeneous donor-acceptor interface at the interfiber interface.

5. The composite sensor of claim 4 , wherein the donor nanofiber is formed from a dodecyl-substituted arylene-ethynylene tetracycle (ACTC).

6. The composite sensor of claim 4 , wherein the donor nanofiber comprises oligothiophene, polythiophene, oligofluorene, polyfluoene, oligocarbazole, polycarbazole, arylene-ethynylene tetracycline, dithiophene, [1]benzothieno[3,2-b][1]benzothiophene, anthracene, tetracene, pentacene, pyrene, perylene, oligo(p-phenylene vinylene) (OPV), poly(p-phenylene vinylene) (PPV), or combinations thereof.

7. The composite sensor of claim 4 , wherein the donor nanofiber is formed of:

wherein R=(C n H 2n+1 or O—C n H 2n+1 ) and n=1-30.

8. The composite sensor of claim 4 , wherein the acceptor nanofiber comprises 3,4,9,10-perylenedicarboximide (PTCDI), naphthalene diimide (NDI), pyrrolo[3,4-c]pyrrole-1,4-dione (PPO), or combinations thereof.

9. The composite sensor of claim 1 , wherein the first and second nanofibers comprise single-walled or multiple-wall carbon nanotube fibers non-covalently bonded with a carbon nanotube dispersant including the interdigitated alkyl chains, such that the first nanofibers and second nanofibers are compositionally homogeneous.

10. The composite sensor of claim 9 , wherein the carbon nanotube dispersant comprises a monomer, oligomer, or polymer that contains at least one of thiophene, pyrene, carbazole, fluorene, phenylene, arylene, vinylene, aniline, imine, azole, pyrrole, porphyrin, phthalocyanine, acenes, DNA, naphthalene, anthracene, perylene, styrene, or a combination thereof.

11. The composite sensor of claim 10 , wherein the network is formed by casting a solution of the carbon nanotube dispersant with the carbon nanotube dispersed therein on a substrate and forming a uniform thin film on the substrate.

12. The composite sensor of claim 1 , further comprising a pair of electrodes electrically associated with the network such that an electrical conductivity measurement occurs across the network.

13. The composite sensor of claim 1 , wherein the sensing material is fabricated into chemiresistors such that the alkane vapor is detected via monitoring the electrical current change.

14. A method of detecting alkanes, comprising:

a) exposing a network of contacting nanofibers having multiple contact points each forming an interfiber interface of interdigitated alkyl chains to a suspected target compound source;

b) measuring an electrical response of the network of nanofibers caused by the alkanes adsorbing at the interfiber interface and increasing an interfiber distance between first and second nanofibers so as to decrease the charge transfer efficiency; and

c) displaying a detection metric based on the electrical response.

15. The method of claim 14 , wherein a temperature of detection is 32-167° F. (0-75° C.).

16. The method of claim 14 , wherein the sensor is reusable.

17. The method of claim 14 , wherein a limit of detection of the method is below a 1% saturated vapor pressure of the analyte.

18. The method of claim 14 , wherein the electrical response of the network of nanofibers is discernible between alkanes of different lengths.

19. The method of claim 14 , wherein the electrical response detects the alkanes in less than 3 seconds and provides the detection metric within 6 seconds.

20. The method of claim 14 , wherein the detection metric is selected from the group consisting of a change in conductivity, change in resistance, change in voltage, change in current, and combinations thereof.

21. The method of claim 14 , wherein the first nanofiber is a donor nanofiber and the second nanofiber is an acceptor nanofiber.

22. The method of claim 14 , wherein the first and second nanofibers are single-walled or multiple-wall carbon nanotube fibers non-covalently bonded with a carbon nanotube dispersant including the interdigitated alkyl chains.