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Preferential Association of Segment Blocks in Polyurethane Nanocomposites

Research and Teaching Output of the MIT Community

Show simple item record James-Korley, LaShanda T. Liff, Shawna M. Kumar, Nitin McKinley, Gareth H. Hammond, Paula T. 2007-01-23T12:03:41Z 2007-01-23T12:03:41Z 2007-01-23T12:03:41Z
dc.description Submitted to Macromolecules en
dc.description.abstract Controlling the level of dispersion of silicate layers in polymer matrices through intermolecular interactions and exploiting these interactions to enhance thermomechanical behavior are key challenges in the field of polymer nanocomposites. In this investigation, unmodified Laponite platelets are dispersed in a segmented polyurethane containing polar, hydrophilic soft segments and a hydrophobic hard segment using a novel solvent exchange method and compared to polyurethane nanocomposites containing more hydrophobic hard and soft domains. It was determined that the silicate layers were preferentially, but not exclusively, attracted to the hydrophilic, polar soft domains. An apparent micro-phase segregated morphology was observed in transmission electron microscopy for this system, revealing regions of exfoliation and intercalation. According to polarizing optical microscopy, strain-induced alignment is inhibited for this polyurethane nanocomposite, which is reflected in dramatic reductions in tensile strength and ultimate extensibility. In comparison, the Laponite discs appear to be preferentially, but not exclusively, embedded to the hard domains in the segmented polyurethanes containing more hydrophobic hard and soft domains. Exfoliation of the clay platelets leads to enhanced modulus and toughness without a reduction in extensibility. This study provides clues for exploiting silicate-polymer interactions to tune material properties without chemical modification. en
dc.description.sponsorship Institute for Soldier Nanotechnology (ISN) at MIT en
dc.format.extent 2367674 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.relation.ispartofseries 06-P-07 en
dc.subject Polyurethane nanocomposite en
dc.subject block copolymer polarity en
dc.subject Preferential segregation en
dc.title Preferential Association of Segment Blocks in Polyurethane Nanocomposites en
dc.type Preprint en

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