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Science 12 August 1994:
Vol. 265. no. 5174, pp. 940 - 942
DOI: 10.1126/science.265.5174.940
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Articles

Controlling Molecular Order in "Hairy-Rod" Langmuir-Blodgett Films: A Polarization-Modulation Microscopy Study

V. K. Gupta 1, J. A. Kornfield 1, A. Ferencz 2, and G. Wegner 2

1 Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
2 Max-Planck-Institut für Polymerforschung, Postfach 3148, D-6500 Mainz, Germany

The interplay of molecular weight, layer thickness, and thermal annealing in controlling molecular order in ultrathin Langmuir-Blodgett films is characterized with the use of polarization-modulation laser-scanning microscopy. The degree and direction of molecular alignment can be imaged rapidly and sensitively through the magnitude and orientation of linear dichroism in Langmuir-Blodgett films of rodlike poly(phthalocyaninatosiloxane) (PcPS). Images are presented for films as thin as two molecular layers (sim44 angstroms). Molecular alignment along the transfer direction is much stronger for films of PcPS with sim25 repeat units (sim10 nanometers long) than for those with sim50 repeat units (sim20 nanometers long). Enhancement of alignment by thermal annealing is also much greater for PcPS-25 than PcPS-50. Intimate interaction with the substrate suppresses improvement in alignment by annealing, evident by an anomalously small increase in anisotropic absorption of the first two layers.

Submitted on April 27, 1994
Accepted on June 27, 1994


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
A route to hierarchical materials based on complexes of metallosupramolecular polyelectrolytes and amphiphiles.
D. G. Kurth, P. Lehmann, and M. Schutte (2000)
PNAS 97, 5704-5707
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Science. ISSN 0036-8075 (print), 1095-9203 (online)