Molecular Alignment of n-Alkanes and Head-to-Tail-Type Poly(3-Alkylthiophene) on Substrates: Study with Films Prepared by Casting and Vacuum Deposition

ABSTRACT

Cast and vacuum-deposited films of several kinds of n-alkanes with different crystal systems were made on a glass substrate. X-ray diffraction (XRD) data showed that n-alkane molecules in both the cast and the vacuum-deposited films were essentially aligned perpendicularly on the substrate. When the vacuum-deposited film of n-alkane became thicker, the XRD pattern indicated that n-alkane molecules in the upper layer lay on the perpendicularly aligned n-alkane layer. Molecular alignment of the film of head-to-tail-type poly(3-hexylthiophene-2,5-diyl), HT-P3HexTh, also depended on the thickness of the film.

Keywords:

• casting
• molecular alignment
• n-alkane
• poly(3-hexylthiophene-2,5-diyl)
• vacuum deposition

Acknowledgments

This research was partly supported by the 21st-Century Center of Excellence program.

Notes

^a From the (00l) peaks with d _l the d spacing of the original peak (d = d _l  × l) was evaluated. The d spacings calculated from the (00l) peaks (l = 1, 2,…) were averaged to give the value given in the parentheses.

^b Data of additionally observed peak for the upper layer of the thicker film (cf. the text).

^a The molar ratio of n-alkane in the solution used for film preparation. Cast from chloroform.

^b The peak assigned for (001) plane of n − C₃₀H₆₂ is described as 30-(001). (00l) diffraction peak of new crystal phase are described as X-l. Three new crystalline phases were observed in this study.

^a The molar ratio of n-alkane in the solution used for film preparation. Cast from chloroform.

^b The peak assigned for (001) plane of n − C₃₀H₆₂ is described as 30-(001).(00l) diffraction peak of new crystalline phase is described as Y-l.

^a The molar ratio of n-alkane in the solution used for film preparation. Cast from chloroform.

^b The peak assigned for (002) plane of n-C₂₉H₆₀ is described as 29-(002). (00l) diffraction peak of a new crystalline phase is described as Z-l.