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Title: Nematic-like stable glasses without equilibrium liquid crystal phases

In this paper, we report the thermal and structural properties of glasses of posaconazole, a rod-like molecule, prepared using physical vapor deposition (PVD). PVD glasses of posaconazole can show substantial molecular orientation depending upon the choice of substrate temperature, T substrate, during deposition. Ellipsometry and IR measurements indicate that glasses prepared at T substrate very near the glass transition temperature (T g) are highly ordered. For these posaconazole glasses, the orientation order parameter is similar to that observed in macroscopically aligned nematic liquid crystals, indicating that the molecules are mostly parallel to one another and perpendicular to the interface. To our knowledge, these are the most anisotropic glasses ever prepared by PVD from a molecule that does not form equilibrium liquid crystal phases. These results are consistent with a previously proposed mechanism in which molecular orientation in PVD glasses is inherited from the orientation present at the free surface of the equilibrium liquid. This mechanism suggests that molecular orientation at the surface of the equilibrium liquid of posaconazole is nematic-like. Posaconazole glasses can show very high kinetic stability; the isothermal transformation of a 400 nm glass into the supercooled liquid occurs via a propagating front that originates at the freemore » surface and requires ~10 5 times the structural relaxation time of the liquid (τ α). We also studied the kinetic stability of PVD glasses of itraconazole, which is a structurally similar molecule with equilibrium liquid crystal phases. Finally, while itraconazole glasses can be even more anisotropic than posaconazole glasses, they exhibit lower kinetic stability.« less
Authors:
 [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [1] ;  [2] ; ORCiD logo [1]
  1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemistry
  2. Univ. of Wisconsin, Madison, WI (United States). School of Pharmacy
Publication Date:
Grant/Contract Number:
SC0002161; DMR-1234320; DMR-1121288
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 5; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; free surface; ellipsometry; liquid surfaces; physical vapor deposition; nematic liquid crystals; glasses; anisotropy; birefringence; glass transitions
OSTI Identifier:
1465678
Alternate Identifier(s):
OSTI ID: 1361753

Gómez, Jaritza, Gujral, Ankit, Huang, Chengbin, Bishop, Camille, Yu, Lian, and Ediger, M. D.. Nematic-like stable glasses without equilibrium liquid crystal phases. United States: N. p., Web. doi:10.1063/1.4974829.
Gómez, Jaritza, Gujral, Ankit, Huang, Chengbin, Bishop, Camille, Yu, Lian, & Ediger, M. D.. Nematic-like stable glasses without equilibrium liquid crystal phases. United States. doi:10.1063/1.4974829.
Gómez, Jaritza, Gujral, Ankit, Huang, Chengbin, Bishop, Camille, Yu, Lian, and Ediger, M. D.. 2017. "Nematic-like stable glasses without equilibrium liquid crystal phases". United States. doi:10.1063/1.4974829. https://www.osti.gov/servlets/purl/1465678.
@article{osti_1465678,
title = {Nematic-like stable glasses without equilibrium liquid crystal phases},
author = {Gómez, Jaritza and Gujral, Ankit and Huang, Chengbin and Bishop, Camille and Yu, Lian and Ediger, M. D.},
abstractNote = {In this paper, we report the thermal and structural properties of glasses of posaconazole, a rod-like molecule, prepared using physical vapor deposition (PVD). PVD glasses of posaconazole can show substantial molecular orientation depending upon the choice of substrate temperature, Tsubstrate, during deposition. Ellipsometry and IR measurements indicate that glasses prepared at Tsubstrate very near the glass transition temperature (Tg) are highly ordered. For these posaconazole glasses, the orientation order parameter is similar to that observed in macroscopically aligned nematic liquid crystals, indicating that the molecules are mostly parallel to one another and perpendicular to the interface. To our knowledge, these are the most anisotropic glasses ever prepared by PVD from a molecule that does not form equilibrium liquid crystal phases. These results are consistent with a previously proposed mechanism in which molecular orientation in PVD glasses is inherited from the orientation present at the free surface of the equilibrium liquid. This mechanism suggests that molecular orientation at the surface of the equilibrium liquid of posaconazole is nematic-like. Posaconazole glasses can show very high kinetic stability; the isothermal transformation of a 400 nm glass into the supercooled liquid occurs via a propagating front that originates at the free surface and requires ~105 times the structural relaxation time of the liquid (τα). We also studied the kinetic stability of PVD glasses of itraconazole, which is a structurally similar molecule with equilibrium liquid crystal phases. Finally, while itraconazole glasses can be even more anisotropic than posaconazole glasses, they exhibit lower kinetic stability.},
doi = {10.1063/1.4974829},
journal = {Journal of Chemical Physics},
number = 5,
volume = 146,
place = {United States},
year = {2017},
month = {2}
}