Surface alignment of P3HT and other conductive polymers

In summary, The orientation of poly(3-hexyl thiophene) and other conductive polymers on a surface, such as silicon/silicon dioxide, can either be "edge-on" or "face-on". This alignment is due to the interaction with the substrate, which can be either enthalpic or entropic depending on the type of interaction (chemical or ion exchange). The most common reason for the "edge-on" alignment is the hydrophobicity of the aromatic thiophene rings compared to the alkyl tails.
  • #1
Tom_Bristol
2
0
Hi all,

It is well known that poly(3-hexyl thiophene) and other conductive polymers with alkyl substituents align when deposited on a surface (e.g. by spin coating or drop casting). The common orientations for P3HT on silicon/silicon dioxide are "edge-on" in which the alkyl side-chains point normal to the surface, and "face-on" in which the thiophene rings lie parallel to the surface. I have read quite a few papers that discuss this observation, for example these two highly cited Nature articles:

[1] http://www.nature.com/nature/journal/v401/n6754/full/401685a0.html
[2] http://www.nature.com/nmat/journal/v5/n3/full/nmat1590.html

My question is: what is the exact energetic reason for this alignment. The "edge-on" alignment is most common and my rationale for this is that the SiO2 surface is quite polar. The aromatic thiophene rings are more hydrophobic than the alkyl tails, thus it is favourable for the polymers to stand up such that the thiophene rings do not interact with the substrate. The second article I posted does discuss the mechanism a little but I am looking for a good reference that explains this phenomenon.

Many thanks.
 
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  • #2
in my view, in the case of thin polymer film assembly, alignment will be strongly governed by the type of interaction with the substrate. If this is agreed upon, then the energetic explanation depends on the type of interaction. Is it chemical (covalent), with a functionalized substrate? Then the driving force for self assembly is probably enthalpic. Is it based on ion exchange? Then it is most likely entropic.
 

FAQ: Surface alignment of P3HT and other conductive polymers

What is the importance of surface alignment in conductive polymers?

Surface alignment is crucial in conductive polymers because it determines the orientation and arrangement of polymer chains on the surface, which can greatly affect the electrical properties of the material.

How is surface alignment of P3HT and other conductive polymers achieved?

The surface alignment of P3HT and other conductive polymers can be achieved through various methods such as substrate surface treatment, mechanical rubbing, and electric field alignment techniques.

What factors influence the surface alignment of conductive polymers?

The surface properties of the substrate, the type of conductive polymer, and the method of alignment are some of the factors that can influence the surface alignment of conductive polymers.

Can surface alignment of conductive polymers be controlled?

Yes, surface alignment of conductive polymers can be controlled by adjusting the parameters of the alignment method and by using different substrate surface treatments to achieve the desired orientation and arrangement of polymer chains on the surface.

What are the potential applications of surface aligned conductive polymers?

Surface aligned conductive polymers have a wide range of applications in electronics, optoelectronics, and energy devices due to their improved electrical properties and higher charge carrier mobility.

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