Three-Dimensional Observation of Phase-Separated Poly(Methyl Methacrylate)/Poly(Styrene-ran-4- bromostylene) Blends by 3D NMR Microscopy with X-ray Microscopy Satoshi Koizumi, 1 Yuji Yamane, 1 Shigeki Kuroki, 1 Isao Ando, 1 Yukihiro Nishikawa, 2 Hiroshi Jinnai 2 1 Department of Chemistry and Materials Science, International Research Center of Macromolecular Science, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552, Japan 2 Department of Polymer Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan Received 1 December 2005; accepted 23 April 2006 DOI 10.1002/app.24952 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Three-dimensional (3D) image patterns of phase-separated poly(methyl methacrylate) (PMMA)/poly (styrene-ran-4-bromostyrene) (PS-Br) blends heated at 1808C for 6, 8, and 10 h were observed by 3D NMR mi- croscopy with 3D X-ray microscopy in order to character- ize the 3D structure of the polymer blends using a stand- ard 3D reconstruction protocol program for obtaining the 3D digital array of the PS-Br/PMMA morphologies. The phase-separated structure of the polymer blends in several 10-mm scales was reasonably characterized. The phase-sep- arated structure of polymer blends by 3D NMR images was quantitatively consistent with that by 3D X-ray images. It can be said that 3D NMR microscopy is a very useful means for analyzing the 3D structure of phase-separated polymer blends as well as 3D X-ray images. Ó 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 470–475, 2007 Key words: three-dimensional structure; NMR imaging; 3D NMR microscopy; 3D X-ray microscopy; phase-separated PMMA/PS-Br blends INTRODUCTION It has been demonstrated that NMR imaging is a very useful means for obtaining nondestructively mm-scale spatial information on probe molecules in bulk mat- ters with mm-scale cavities. 1,2 For this, NMR imaging has been successfully used to elucidate the stimulus- response process of polymer gels under the applica- tion of external stimuli, such as stress, heating, and electric field, the transportation of probe metal ions in a polymer gel under electric field, and the number of channel cavities and its size distribution in a polymer gel. 3–11 Studies of bicontinuous structures developed via spinodal decomposition (SD) have been a research theme among researchers dealing with binary mix- tures of molecular fluids, binary alloys, and polymer blends. 12,13 Scattering techniques such as light, small- angle X-ray, and small-angle neutron have been extensively used to examine the phase-separated structure of polymer blends. 13–15 As a result of these studies, a great deal of information on the time evolu- tion of the phase-separated structures has been obtained. Most recently, laser scanning confocal mi- croscopy (LSCM) was shown to be an excellent tool to capture the 3D interface structure of polymer blends. 16–18 By using LSCM, the time evolution of the interface between two coexisting phases developed via SD was quantitatively captured in 3D images. At present, high-resolution X-ray computed tomography (X-ray CT) was also developed and it will be possible to provide very useful quantitative information about the mm-scale 3D structures of polymer blend systems; the mechanism of phase separation for polymer blends has been clarified. In the X-ray CT method, the contrast of images comes from the difference of absorption for X-ray, which corresponds to the difference of electron den- sity. Polymers have almost the same absorption for X- ray. If polymer blends are observed by X-ray CT, heavy atom-labeling is necessary for contrast enhance- ment. In the case of LSCM, the labeling of fluorescence species is necessary for contrast enhancement. On the other hand, in 1 H NMR microscopy the con- trast of images comes from the difference of 1 H spin density, 1 H spin-lattice relaxation time (T 1 ), and 1 H spin-spin relaxation time (T 2 ). Here, the difference of T 1 and T 2 corresponds to the difference in molecular motion. Thus, one does not need to label any specified Correspondence to: S. Kuroki (skuroki@polymer.titech.ac.jp). Journal of Applied Polymer Science, Vol. 103, 470–475 (2007) V VC 2006 Wiley Periodicals, Inc.