Friction transfer

M. Misaki, Y. Ueda, S. Nagamatsu, Y. Yoshida, N. Tanigaki, and K. Yase, Formation of singlecrystal-like poly(9,9-dioctylfluorene) thin films by the friction-transfer technique with subsequent thermal treatments, Macromolecules, 37 6926-6931, 2004. 

S Nagamatsu, W Takashima, K Kaneto, Y Yoshida, N Tanigaki, K Yase, and K Omote, Backbone arrangement in friction-transferred regioregular poly(3-alkylthiophene)s, Macro molecules, 36 5252-5257, 2003. 

RE Gill, G Hadziioannou, P Lang, F Gamier, and JC Wittmann, Highly oriented thin films of a substituted oligo(para-phenylenevinylene) on friction-transferred PTFE substrates, Adv. Mater., 9 331-338, 1997. 

Y Yoshida, JP Ni, N Tanigaki, and K Yase, Polarized electroluminescence of oligophenyl thin films prepared on friction transferred poly(p-phenylenes), Mol. Cryst. Liq. Cryst., 370 69-72, 2001. 

When a glass plate which is heated e.g. at 130°C is rubbed with a polytetrafluoroethylene (PTFE) briquette, a highly oriented thin film (2— 100 nm thick) of PTFE can be made on the plate such a film is termed a friction-transfer layer [24]. This method is applicable to make thin oriented layers of other polymers. Various kinds of organic compormds can be oriented on the PTFE friction-transfer layer from vapor phase, from solutions and from the melts [24]. 

Pentacene and tetracene films can be oriented by using friction-transferred PTFE polymer substrates (see Section 3.3). The films consist of both crystallographic... 

Poly[(p-butoxyphenyl)phenylsilane] (PBPPS) has been employed as an emissive layer of an organic EL device.95 PBPPS was spin coated onto an uniaxially oriented poly(diethylsilane) (PDES) ultrathin film. Polarized NUV-EL was observed and the polarization direction was found to be identical with the drawing direction of the friction-transfer process for the PDES film, indicating that PBPPS in the emissive layer was aligned parallel to the uniaxial orientation of PDES. 

Alternative methods, including friction transfer [71] and directional epitaxial crystallization [76], have also been used successfully in the alignment of PFs. In the friction transfer method one provides a crystalline templating substrate, (e.g., PTFE) and then applies a CP over layer. As in the case of a rubbed substrate, the CP does not significantly impact the orienting ability of the aligned substrate. This process is commonly referred to as graphoepitaxy. 

Polymer-metal friction pairs are also characterized by frictional transfer of material. This implies the material displacement from the polymer part friction surface onto that of the metal counterbody. Macrotransfer is realized either as a fatigue detachment of polymer particles sticking to the counterbody or as galling, i.e. sticking of the viscous-flow fragments from the polymer surface layer, their extension and movement in the friction direction. 

The value of polymer part wear in acid is roughly of the same order as in air. The behavior of wear curves of the polymer samples during dry friction is attributed to frictional transfer (curves 4 -6 ) in which case the curves are arranged in order of material strength the strongest non-modified PE wears less. Impregnation of the mineral oil and Cl improves chemical resistance of PE and it therefore wears less (curves 5 and 6) than the pure PE (curve 4). 

Additional orientation can be seen in x-ray studies of P3HT and P3DDT upon friction transfer byNagamatsu [132]. 

K. Yase, E.-M. Han, K. Yamamoto, Y. Yoshida, N. Takada and N. Taniguchi, One-dimensional growth of phenylene oligomer single crystals of friction-transferred poly(p-phenylene) film, Jpn. J. Appl. Phys.. 36, 2843-2848 (1997). 

Brinkmann, M., Graff, S., Straupe, C., Wittmann, J.-C., Chaumont, C., Nuesch, F., Aziz, A., Schaer, M., Zuppiroh, L., 2003. Orienting tetracene and pentacene thin films onto friction-transferred poly(tetrafluoroethylene) substrate. The Journal of Physical Chemistry B 107, 10531-10539. 

For polymers, anisotropic friction 10) was observed on lamellar crystals II -13 as well as on extended-chain crystals obtained by friction transfer deposition 14). The anisotropic friction for lamellar crystals was explained by the occurrence of chain-folding oriented preferentially in planes parallel to the corresponding crystal face. For extended-chain crystals friction anisotropy observed parallel and perpendicular to the chain direction was interpreted by the interlocking asperity model. In this paper we give an overview regarding our nanotribological observations on oriented high density polyethylene (HDPE), poly(tetrafluoroethylene) (PTFE) and on crystals of polyethylene (PE) and transcrystallized poly(ethylene oxide) (PEO). 

Materials and Orientation. The HDPE samples used in this study were obtained by (a) compression in a channel die 15, 16) and (b) by orienting a slider 17) in friction transfer 18). PTFE surfaces were unidirectionally oriented by sliding a block of... 

Nagamatsu S, Takashima W, Kaneto K, Yoshida Y, Tanigaki N, Yase K. Backbone arrangement in Friction-Transferred regioregular poly(3-alkylthiophene)s. Macromolecules 2003 36 5252-5257. 

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