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Macromolecules , 38 , 4947 (2005). Macromolecules , ASAP (July 13, 2005).

Controlled Crystallization in Novel Block Copolymers Richard A. Register, Princeton University, DMR-0220236. The hexagonally-perforated lamellar (HPL) structure is appealing as a nanostructured template ( e.g. , to direct crystallization) due

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Macromolecules , 38 , 4947 (2005). Macromolecules , ASAP (July 13, 2005).

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  1. Controlled Crystallization in Novel Block CopolymersRichard A. Register, Princeton University, DMR-0220236 The hexagonally-perforated lamellar (HPL) structure is appealing as a nanostructured template (e.g., to direct crystallization) due to its unique combination of two- and three-dimensional continuity of the components. Unfortunately, previous observations of HPL in block copolymers have shown it to be unstable (relative to other structures), and to possess a disordered arrangement of the perforations unless sheared. We have synthesized polystyrene-poly(ethylene-alt-propylene) diblock copolymers, S/EP, that forms highly-regular HPL structures which persists indefinitely. In this system, HPL can be accessed from other, stable phases (cylinders or lamellae) simply by changing temperature; we have elucidated these structural transformations, which require from seconds to hours to occur, via in situ small-angle x-ray scattering (SAXS). S S EP EP S 2D 50 nm 3D Left: schematic HPL structure in S/EP diblocks showing 2D continuity of (minority) S domains and 3D continuity of (majority) EP domains. Top: TEM image of a thin section of HPL. 2D Left: Synchrotron SAXS pattern of an unsheared sample of S/EP 9/14 simply heated to 260oC. Peaks indicate a highly regular ABC stacking of the perforations. Left: Time-resolved SAXS for S/EP 7/13 following a quench from 180 to 140oC, which causes the structure to transform from cylinders (C) to HPL in the ensuring 40 minutes, as shown in the inset. S/EP 7/13 Macromolecules, 38, 4947 (2005). Macromolecules, ASAP (July 13, 2005). Strucral transformatio between amorphous phase, mesophases (nematic and smectic C) and triclinic crystalline phase induced by stretching.

  2. Controlled Crystallization in Novel Block CopolymersRichard A. Register, Princeton University, DMR-0220236 Outreach: On March 17, Princeton University hosted the Science and Engineering Exposition, bringing nearly 1000 local middle-school children to campus for a fast-paced exposure to the excitement of science and engineering. The Register group ran a series of demonstrations on the unusual behavior of polymers, and the microscopic structure which lies behind it (such as superabsorbent polymer gels, see photo at left). The event (particularly the polymer demo) was covered in local print and broadcast media, reaching an even wider audience. Group members later ran similar demos in April, at Toll Gate Grammar School in Pennington, and in May, at Super Science Weekend in Trenton. The PI (right) and graduate student Sasha Myers (center) demonstrate the structure and properties of polymer gels. A similar photo ran in the New York Times (March 18, 2005).

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