q m = 0.0224 ยฑ1 , which gives the domain [9] center-to-center spacing of 280 (D = 2p/q m ). A number of additional broad scattering maxima were also observed at higher q, but the positions are somewhat unclear for this sample due to the noise in the data. Figure shows a SAXS profile of porous MSSQ generated by 40 wt.-% of 4c. It shows a strong first scattering peak with a number of higher-order scattering maxima caused by interpore interference, indicating that the spatial arrangement of the pores is regular. The pore spacing obtained from q m is ~310 for this sample. Two other broad scattering maxima marked by arrows can be attributed to the form factor. Assuming spherical pores, the scattering maxima give a radius of 75 for 4c and 39 for 4a, consistent with the pore sizes estimated from the transmission electron microscopy (TEM) images.
In summary, environmentally responsive star-shaped copolymers with a compatiblilizing outer corona were used to organize the MSSQ vitrificate into nanostructures through a matrix-mediated collapse of the interior core. DMA, SANS, and SAXA measurements strongly suggest that the core is phase separated in the as-cast films and serves, as a macromolecular template, where one star generates one pore. The porous morphology was strongly dependent on the arm number, molecular weight of the interior core as well as the volume fraction of copolymer in MSSQ mixtures. The bottomยฑup/ coreยฑout approach to star porogens produced a porous structure with pores that range in size from 7 to 40 nm, depending on polymer molecular weight and architecture.