Morphological Change of Poly(4-\textit{tert}-butylstyrene-\textit{block}-4-\textit{tert}-butoxystyrene) in a Wide Range of Segregation Strength Though Hydrolysis Reaction

Morphological change of symmetric poly(4-\textit{tert}-butylstyrene-\textit{block}-4-\textit{tert}-butoxystyrene)s (BO) upon hydrolysis reaction was investigated by transmission electron microscopy and small-angle X-ray scattering. Segregation strength, \textit{$\chi $N} (\textit{$\chi $}: interaction parameter, $N$: degree of polymerization), which governs the chain dimension, was gradually tuned since poly(4-\textit{tert}-butoxystyrene) (O), a non-polar polymer, can be converted into poly(4-hydroxystyrene) (H), a polar one, through hydrolysis. Samples with different molecular weights and conversion rates of O into H, $f_{H}$s, were prepared. Domain spacing of the lamellar structure, $D$, increased as $f_{H}$ increases where it abruptly increased at a critical $f_{H}$, indicating that the chain stretched perpendicularly to the lamellar interface. The degree of chain stretching compared to a random coil, $D$/$D_{0}$s ($D_{0}$: correlation length at $f_{H}$=0), were scaled by \textit{$\chi $N}. Three regimes can be distinguished in the plot of ($D$/$D_{0})$ vs. \textit{$\chi $N}: (I) the weak segregation regime with $D$/$D_{0}\sim $1 that associates with the scaling behavior of $D\sim N^{0.55}$, (II) the intermediate segregation regime with the scaling behavior of ($D$/$D_{0})\sim $(\textit{$\chi $N})$^{0.34}$, and (III) the strong segregation regime with $D$/$D_{0}\sim $2.3 which corresponds to $D\sim N^{0.67}$.