期刊
MACROMOLECULES
卷 41, 期 22, 页码 8745-8752出版社
AMER CHEMICAL SOC
DOI: 10.1021/ma801458w
关键词
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资金
- National Science Foundation [DMR-0605856]
- Cornell Center for Materials Research (CCMR)
- Materials Research Science and Engineering Center of the National Science Foundation [DMR-0520404]
- NSF & NIH/NIGMS via NSF Award [DMR-0225180]
Block copolymer-polymer derived ceramic (PDC) precursor nanocomposites were prepared using amorphous poly(isoprene-block-(dimethylamino)ethyl methacrylate) (PI-b-PDMAEMA) and semicrystalline poly (isoprene-block-ethylene oxide) (PI-b-PEO) block copolymers as structure directing agents for poly(ureamethylvinyl)silazane (PUMVS). Studies on hybrid morphologies were performed using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). In the amorphous system, the PUMVS preferentially swells the PDMAEMA, and a systematic increase of the PUMVS to PI-b-PDMAEMA weight ratio resulted in lamellar, hexagonally packed cylindrical and body-centered cubic packed spherical morphologies. Crystallization of PEO in PI-b-PEO/PUMVS hybrids led to crystalline lamellar morphologies over a large range of PUMVS to PI-b-PEO weight ratios. The d-spacing of the PI-b-PEO/PUMVS hybrids increased only slightly upon PUMVS loading, because the strong chain stretching in the PI block is progressively relaxed as the PUMVS swells the PEO. Annealing of the PI-b-PEO/PUMVS system at elevated temperatures led to suppression of the PEO crystallization, resulting in order-order phase transitions.
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