Controlled radical polymerization induced macro- and microphase separation investigated by focusing ultra-small-angle neutron scattering

Motokawa, Ryuhei   ; Koizumi, Satoshi; Hashimoto, Takeji; Iida, You*

We constructed a focusing ultra-small-angle scattering spectrometer (SANS-J-II) at research reactor JRR3, Tokai, Japan. Focusing unlra-small-angle neutron scattering (USANS) and conventional small-angle neutron scattering (SANS) can observe the length scale about 1000 nm - 100 nm and 100 nm - 1 nm, respectively. 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. In the reaction process to synthesize PS block chains from the end of PMMA block chain, we found the interplay between macro and microdomain structures as follows. As the polymerization proceeds, (i) first by polymerization-induced disorder-order 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.