Research

Overview of Conjugated Polymers and Carbon Nanotubes Interaction

  • Conjugated polymers can be processed to interact with carbon nanotubes, resulting in dark dispersions of nanotube solutions.

Creation of Nanotube Dispersion Solution

  • By removing side chains from conjugated polymers, a dispersion with carbon nanotubes can be formed.

    • These polymers will still have interactions with carbon nanotubes despite the removal of side chains.

    • The removal of side chains is critical for the precipitation process in the dispersion solution.

Importance of Side Chains

  • Side chains on polymers generally help keep antigens in solution.

  • Upon removal, the solution is expected to precipitate due to the absence of stabilizing side chains.

    • A comparison with control experiments shows that fluoride does not influence the control setup, confirming that effects stem from side chain removal.

Impact on Conductivity

  • The primary goal of the experiment was to investigate conductivity changes following the removal of the side chains.

    • As side chains are removed, the carbon nanotubes can come into closer contact, enhancing conductivity.

  • Evidence of increased conductivity was established through several observations:

    1. Conductivity of thin films of these carbon nanotubes, $k$, was monitored before and after treatment.

    2. After removal of side chains using a fluoride solution, a significant increase in conductivity was recorded:

    • A measured change of approximately 100 times greater in conductivity.

    1. Control experiments demonstrated no changes in conductivity.

  • When thin films were connected in a loop circuit with a light bulb and battery, the following results were observed:

    • Before side chain removal: light bulb remained off.

    • After side chain removal: light bulb turned on, indicating successful conductivity of the films.

Development of Flexible, Conductive Materials

  • A student named Dora conducted further experiments to laminate carbon nanotube films onto elastomer surfaces (rubbery materials).

    • The rough surface of the elastomer:

    • Appears smooth to touch but is micron-level rough.

  • When two elastomer-coated films are sandwiched together, connectivity issues arise due to minimal contact points on rough surfaces.

    • Applying mechanical pressure allows them to make better contact, thus increasing vertical conductivity across these films.

    • Measurement: Initial resistance recorded at 1.7 kΩ, reduced to 200 Ω under a 50g weight.

    • Demonstrated that pressure can change the resistance across these films.

Measurement and Responsiveness of the Device

  • Dora employed an Instron instrument for precise pressure application and measurement over multiple trials.

    • Two significant findings:

    1. Instantaneous response time to applied pressure:

    • Pressure increase causes immediate conductivity increment; response occurs within ten milliseconds.

    1. Reversible response to pressure:

    • Upon pressure release, conductivity returns to original levels almost instantaneously.

  • Linear behavior in response to varying pressure settings over a wide pressure range was noted.

  • Reproducibility of results:

    • Conducted 20 different pressure trials, maintaining consistency in response curves.

    • Visual data was collated to show reproducible results across 500 repeated experiments.

    • Confirmed precision in pressure response across experimental trials.

Conclusion

  • The experiments successfully demonstrated how the removal of side chains from conjugated polymers can significantly enhance the conductivity of thin films made with carbon nanotubes.

  • Additionally, the integration of these films into elastomer matrices showed promising results for responsive pressure applications.