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Physical vapor deposition as a route...

Gomez, Jaritza.

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Physical vapor deposition as a route to glasses with liquid crystalline order.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Physical vapor deposition as a route to glasses with liquid crystalline order./
Author:	Gomez, Jaritza.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2017,
Description:	126 p.
Notes:	Source: Dissertation Abstracts International, Volume: 78-06(E), Section: B.
Contained By:	Dissertation Abstracts International78-06B(E).
Subject:	Materials science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10254141
ISBN:	9781369498424

Physical vapor deposition as a route to glasses with liquid crystalline order.
Gomez, Jaritza.

Physical vapor deposition as a route to glasses with liquid crystalline order. - Ann Arbor : ProQuest Dissertations & Theses, 2017 - 126 p.

Source: Dissertation Abstracts International, Volume: 78-06(E), Section: B.

Thesis (Ph.D.)--The University of Wisconsin - Madison, 2017.

Physical vapor deposition (PVD) is an effective route to prepare glasses with a unique combination of properties. Substrate temperatures near the glass transition (Tg) and slow deposition rates can access enhanced mobility at the surface of the glass allowing molecules at the surface additional time to sample different molecular configurations. The temperature of the substrate can be used to control molecular mobility during deposition and properties in the resulting glasses such as higher density, kinetic stability and preferential molecular orientation.

ISBN: 9781369498424Subjects--Topical Terms:

543314
Materials science.

Physical vapor deposition as a route to glasses with liquid crystalline order.
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100 1 $a Gomez, Jaritza. $3 3347410
245 1 0 $a Physical vapor deposition as a route to glasses with liquid crystalline order.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2017
300 $a 126 p.
500 $a Source: Dissertation Abstracts International, Volume: 78-06(E), Section: B.
500 $a Adviser: Mark D. Ediger.
502 $a Thesis (Ph.D.)--The University of Wisconsin - Madison, 2017.
520 $a Physical vapor deposition (PVD) is an effective route to prepare glasses with a unique combination of properties. Substrate temperatures near the glass transition (Tg) and slow deposition rates can access enhanced mobility at the surface of the glass allowing molecules at the surface additional time to sample different molecular configurations. The temperature of the substrate can be used to control molecular mobility during deposition and properties in the resulting glasses such as higher density, kinetic stability and preferential molecular orientation.
520 $a PVD was used to prepare glasses of itraconazole, a smectic A liquid crystal. We characterized molecular orientation using infrared and ellipsometry. Molecular orientation can be controlled by choice of Tsubstrate in a range of temperatures near Tg. Glasses deposited at Tsubstrate = Tg show nearly vertical molecular orientation relative to the substrate; at lower Tsubstrate, molecules are nearly parallel to the substrate. The molecular orientation depends on the temperature of the substrate during preparation and not on the molecular orientation of the underlying layer. This allows preparing samples of layers with differing orientations. We find these glasses are homogeneous solids without evidence of domain boundaries and are molecularly flat. We interpret the combination of properties obtained for vapor-deposited glasses of itraconazole to result from a process where molecular orientation is determined by the structure and dynamics at the free surface of the glass during deposition.
520 $a We report the thermal and structural properties of glasses prepared using PVD of a rod-like molecule, posaconazole, which does not show equilibrium liquid crystal phases. These glasses show substantial molecular orientation that can be controlled by choice of Tsubstrate during deposition. Ellipsometry and IR indicate that glasses prepared at Tg -- 3 K are highly ordered. At these Tsubstrate, molecules show preferential vertical orientation and orientation is similar to that measured in aligned nematic liquid crystal. Our results are consistent with a recently proposed mechanism where molecular orientation in equilibrium liquids can be trapped in PVD glasses and suggest that the orientation at the free surface of posaconazole is nematic-like. In addition, we show posaconazole glasses show high kinetic stability controlled by Tsubstrate.
590 $a School code: 0262.
650 4 $a Materials science. $3 543314
650 4 $a Physical chemistry. $3 1981412
690 $a 0794
690 $a 0494
710 2 $a The University of Wisconsin - Madison. $b Chemistry. $3 2049906
773 0 $t Dissertation Abstracts International $g 78-06B(E).
790 $a 0262
791 $a Ph.D.
792 $a 2017
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10254141