Analysis of Order Formation in Block Copolymer Thin Films Using Resonant Soft X-ray Scattering

The lateral order of poly(styrene-block-isoprene) copolymer (PS-b-PI) thin films is characterized by the emerging technique of resonant soft X-ray scattering (RSOXS) at the carbon π* resonance and compared to ordering in bulk samples of the same materials measured using conventional small-angle X-ra...

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Bibliographic Details
Published inMacromolecules Vol. 40; no. 6; pp. 2092 - 2099
Main Authors Virgili, Justin M, Tao, Yuefei, Kortright, Jeffrey B, Balsara, Nitash P, Segalman, Rachel A
Format Journal Article
LanguageEnglish
Published Washington, DC American Chemical Society 20.03.2007
Subjects
Applied sciences
Exact sciences and technology
Organic polymers
Physicochemistry of polymers
Properties and characterization
Structure, morphology and analysis
Monodispersed polymer
Investigation method
Domain structure
Soft X ray
Isoprene copolymer
Diblock copolymer
X ray scattering
Order disorder transformation
Experimental study
Thin film
Styrene copolymer
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Summary:The lateral order of poly(styrene-block-isoprene) copolymer (PS-b-PI) thin films is characterized by the emerging technique of resonant soft X-ray scattering (RSOXS) at the carbon π* resonance and compared to ordering in bulk samples of the same materials measured using conventional small-angle X-ray scattering. We show resonance using theory and experiment that the loss of scattering intensity expected with a decrease in sample volume in the case of thin films can be overcome by tuning X-rays to the π* resonance of PS or PI. Using RSOXS, we study the microphase ordering of cylinder- and sphere-forming PS-b-PI thin films and compare these results to position space data obtained by atomic force microscopy. Our ability to examine large sample areas (∼9000 μm2) by RSOXS enables unambiguous identification of the lateral lattice structure in the thin films. In the case of the sphere-forming copolymer thin film, where the spheres are hexagonally arranged, the average sphere-to-sphere spacing is between the bulk (body-centered cubic) nearest neighbor and bulk unit cell spacings. In the case of the cylinder-forming copolymer thin film, the cylinder-to-cylinder spacing is within experimental error of that obtained in the bulk.
ISSN:0024-9297
1520-5835
DOI:10.1021/ma061734k