1/21/2011
Hierarchical Structure in Nanoscale Thin Films of a Poly(styrene-b- methacrylate grafted with POSS) (PS214-b-PMAPOSS27)
(10568–10581) Macromolecules 43 #24 (2010)
Ahn et al of the Pohang University of Science and Technology, South Korea, Tokyo Institute of Technology, Japan and University of Wisconsin-Madison, Wisconsin prepared an organic−inorganic diblock copolymer, poly(styrene-b-methacrylate grafted with polyhedral oligomeric silsesquioxane) (PS-b-PMAPOSS), with PS (an average degree of polymerization DP of 214) and PMAPOSS (DP = 27) blocks.  The polymer  was stable up to 330 °C with  a glass transition at 96 °C (PS block) and a melting transition at 173 °C (PMAPOSS block).  The diblock copolymer molecules in the thin films undergo phase separation into PS and PMAPOSS domains, which generates a lamellar structure.  On heating, the orthorhombic crystals and the molecularly stacked layers melt over the range 170−190 °C. On subsequent cooling, the orthorhombic crystals and molecularly stacked layers are not fully recovered, which indicates that the formation of orthorhombic crystals and stacked layers in the PMAPOSS domains requires thermal annealing. (RDC 1/19/2011)