Structure, mobility, and interface characterization of self-organized organic-inorganic hybrid materials by solid-state NMR

The local chemical environments, dynamic heterogeneities, and nature of the interface in structured organic-inorganic composites prepared from poly(is oprene-b-ethyleneoxide) block copolymers, (3-glycidyl-oxypropyl)trimethoxys ilane, and aluminum sec-butoxide via a sol-gel process are characterized by solid-state NMR. Such composites self-assemble into the characteristic mor phologies of block copolymer systems, with the inorganic component selectiv ely swelling the poly(ethylene oxide) phases. Here it is shown that the loc al chemical structure of the aluminosilicate component is nearly unperturbe d by addition of the block copolymer and that the combined aluminosilicate/ poly(ethylene oxide) layer is significantly le ss mobile than the polyisopr ene. Spin-diffusion measurements on 8 composite with lamellar morphology in dicate that no significant (>1 nm thick) poly(ethylene oxide) interphase ex ists between the polyisoprene and poly(ethylene oxide)/aluminosilicate laye rs, and therefore, the inorganic and poly(ethylene oxide) phases are intima tely mixed on a molecular level. Implications of these findings for the mat erials properties are discussed.