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Home  >  Journal list  >  Polymer Journal  >  Vol.39  No.12 (2007)  >  pp.1312-1318

Polymer Journal
<<Previous article Vol.39  No.12 (2007)   pp.1312 - 1318 Next article>>

Living Polymerization Induced Macro- and Microdomain Investigated by Focusing Ultra-small-angle Neutron Scattering

Ryuhei Motokawa1), You Iida2), Yue Zhao1), Takeji Hashimoto1) and Satoshi Koizumi1)
1) Research Group for Soft Matter & Neutron Scattering, Advanced Science Research Center, Japan Atomic Energy Agency
2) Department of Physics, Tohoku University


ABSTRACT:  By utilizing a biconcave refractive neutron lens (MgF2) 5-inch size & high resolution position sensitive area photomultiplier with scintillator (ZnS), we constructed a focusing ultra-small-angle neutron scattering (USANS) spectrometer (SANS-J-II) at research reactor JRR3, Tokai, Japan. SANS-J-II can successfully reach to qmin=0.0003 Å−1, where q (=4πsin(θ)⁄λ) is the magnitude of scattering vector given by wavelength λ and scattering angle 2θ, and simultaneously cover conventional small-angle neutron scattering (SANS) region to q=0.004 Å−1. Focusing USANS, thus realized, plays an important role to investigate the time-evolution of hierarchically ordered structures in the living radical polymerization solution, preparing poly(methyl methacrylate)-block-polystyrene (PMMA-b-PS). In the reaction process to synthesize a PS block chain from the end of PMMA block chain, we found the interplay between macro- and microphase separation. SANS at q>0.001 Å−1 determined time-evolving microdomain structures; as the polymerization proceeds, (i) first by order-disorder transition, a lamellar microdomain appears and (ii) second by order-order transitions, the morphologies of microdomains change to PMMA cylinder and successively to PMMA sphere. USANS at q<0.001 Å−1, exhibiting power law scattering (∼q−α) due to macrophase separation between PMMA-b-PS and PS homopolymer (appeared as by product). The exponent α varies from 4 to 2, reflecting a grain boundary of macrodomain rich-in PMMA-b-PS; when a lamellar microdomain appears, Porod law gives α=4, whereas when cylinder and sphere appear, α=2, due to inhomogeniety of the microdomain spatial distribution of the microdomains.


Keyword:
Ultra-small-angle Neutron Scattering/ Small-angle Neutron Scattering/ Living Radical Polymerization/ Phase Separation/ Microdomain

Published online: December 14, 2007
© Copyright, 2007 by The Society of Polymer Science, Japan

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