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

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Physical vapor deposition as a route to glasses with liquid crystalline order./
Author:	Gomez, Jaritza.
Description:	1 online resource (126 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 78-06(E), Section: B.
Subject:	Materials science. -
Online resource:	click for full text (PQDT)
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. - 1 online resource (126 pages)

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

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

Includes bibliographical references

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.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9781369498424Subjects--Topical Terms:

557839
Materials science.
Index Terms--Genre/Form:

554714
Electronic books.

Physical vapor deposition as a route to glasses with liquid crystalline order.
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100 1 $a Gomez, Jaritza. $3 1187137
245 1 0 $a Physical vapor deposition as a route to glasses with liquid crystalline order.
264 0 $c 2017
300 $a 1 online resource (126 pages)
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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.
504 $a Includes bibliographical references
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.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Materials science. $3 557839
650 4 $a Physical chemistry. $3 1148725
655 7 $a Electronic books. $2 local $3 554714
690 $a 0794
690 $a 0494
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a The University of Wisconsin - Madison. $b Chemistry. $3 1187138
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10254141 $z click for full text (PQDT)