抄録
Cl- ion distribution in the polyelectrolyte brush in the amphiphilic diblock copolymer monolayer on the water surface was evaluated by in situ neutron reflectivity (NR) technique with contrast variation method. The X-ray reflectivity (XR) profiles for spread monolayer of poly(diethylsilacyclobutane)-bpoly(methacrylic acid) with NaCl and NaBr as an added salt were well reproduced by 3-box model with assuming hydrophobic, carpet and brush triple layer structure. However, NR profile for 1M NaCl condition could not fitted by 3-box model while those for NaBr and NaCl at lower concentration could be fitted. NR profile under 1M NaCl condition with D2O/H2O(8/2) as subphase, where the contribution from Cl- ions to neutron reflectivity is eliminated, was well fitted with 3-box model with the same nanostructure of monolayer by XR. Hence, we concluded that the disagreement observed for 1M NaCl condition is due to the contribution of Cl- ions whose distribution is inhomogeneous in brush layer. By model fitting of NR profile with inhomogeneous Cl- ion distribution, it was predicted that Cl- ions were concentrated just beneath the carpet layer.
