Thermotropic properties of organic nanocrystals embedded in ultrasmall crystallization chambers

Jeong Myeong Ha, Marc A. Hillmyer, Michael Ward

Research output: Contribution to journalArticle

Abstract

Crystallization of organic compounds in nanometer-scale channels of controlled pore glass (CPG) and porous polystyrene (p-PS), the latter prepared by etching of the polylactide (PLA) component of shear-aligned PS-PLA diblock copolymers, produces crystals with dimensions that reflect the size constraints imposed by the channels. The nanoscopic dimensions of the organic crystals embedded in the channels result in a substantial melting point depression compared with the bulk, as demonstrated here for 2,2,3,3,4,4-hexafluoro-1,5-pentanediol (HFPD) and (R)-(+)-3-methyladipic acid (R-MAA). The melting points decreased with decreasing channel diameter, consistent with the increasing surface-area-to-volume ratio of the crystals. Furthermore, at these length scales the latent heat of melting decreased with decreasing crystal size. The melting point depression for both HFPD and R-MAA was greater in p-PS than in CPG, which can only be explained by interactions of the nanocrystals and their corresponding melts with the channel walls. Collectively, these discoveries reveal that simplified descriptions used in previous investigations of embedded crystals, which were limited to porous glass matrixes and ignored the influence of the channel walls, do not capture all the factors affecting the thermotropic properties of the embedded nanocrystals.

Original languageEnglish (US)
Pages (from-to)1392-1399
Number of pages8
JournalJournal of Physical Chemistry B
Volume109
Issue number4
DOIs
StatePublished - Feb 3 2005

Fingerprint

Crystallization
Nanocrystals
nanocrystals
chambers
crystallization
Crystals
Melting point
Polystyrenes
melting points
Glass
crystals
glass
polystyrene
Acids
Latent heat
porosity
Beam plasma interactions
acids
Organic compounds
Block copolymers

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Thermotropic properties of organic nanocrystals embedded in ultrasmall crystallization chambers. / Ha, Jeong Myeong; Hillmyer, Marc A.; Ward, Michael.

In: Journal of Physical Chemistry B, Vol. 109, No. 4, 03.02.2005, p. 1392-1399.

Research output: Contribution to journalArticle

@article{a23594a3f6c04d0394cb9cb1f09cfb9a,
title = "Thermotropic properties of organic nanocrystals embedded in ultrasmall crystallization chambers",
abstract = "Crystallization of organic compounds in nanometer-scale channels of controlled pore glass (CPG) and porous polystyrene (p-PS), the latter prepared by etching of the polylactide (PLA) component of shear-aligned PS-PLA diblock copolymers, produces crystals with dimensions that reflect the size constraints imposed by the channels. The nanoscopic dimensions of the organic crystals embedded in the channels result in a substantial melting point depression compared with the bulk, as demonstrated here for 2,2,3,3,4,4-hexafluoro-1,5-pentanediol (HFPD) and (R)-(+)-3-methyladipic acid (R-MAA). The melting points decreased with decreasing channel diameter, consistent with the increasing surface-area-to-volume ratio of the crystals. Furthermore, at these length scales the latent heat of melting decreased with decreasing crystal size. The melting point depression for both HFPD and R-MAA was greater in p-PS than in CPG, which can only be explained by interactions of the nanocrystals and their corresponding melts with the channel walls. Collectively, these discoveries reveal that simplified descriptions used in previous investigations of embedded crystals, which were limited to porous glass matrixes and ignored the influence of the channel walls, do not capture all the factors affecting the thermotropic properties of the embedded nanocrystals.",
author = "Ha, {Jeong Myeong} and Hillmyer, {Marc A.} and Michael Ward",
year = "2005",
month = "2",
day = "3",
doi = "10.1021/jp045488v",
language = "English (US)",
volume = "109",
pages = "1392--1399",
journal = "Journal of Physical Chemistry B Materials",
issn = "1520-6106",
publisher = "American Chemical Society",
number = "4",

}

TY - JOUR

T1 - Thermotropic properties of organic nanocrystals embedded in ultrasmall crystallization chambers

AU - Ha, Jeong Myeong

AU - Hillmyer, Marc A.

AU - Ward, Michael

PY - 2005/2/3

Y1 - 2005/2/3

N2 - Crystallization of organic compounds in nanometer-scale channels of controlled pore glass (CPG) and porous polystyrene (p-PS), the latter prepared by etching of the polylactide (PLA) component of shear-aligned PS-PLA diblock copolymers, produces crystals with dimensions that reflect the size constraints imposed by the channels. The nanoscopic dimensions of the organic crystals embedded in the channels result in a substantial melting point depression compared with the bulk, as demonstrated here for 2,2,3,3,4,4-hexafluoro-1,5-pentanediol (HFPD) and (R)-(+)-3-methyladipic acid (R-MAA). The melting points decreased with decreasing channel diameter, consistent with the increasing surface-area-to-volume ratio of the crystals. Furthermore, at these length scales the latent heat of melting decreased with decreasing crystal size. The melting point depression for both HFPD and R-MAA was greater in p-PS than in CPG, which can only be explained by interactions of the nanocrystals and their corresponding melts with the channel walls. Collectively, these discoveries reveal that simplified descriptions used in previous investigations of embedded crystals, which were limited to porous glass matrixes and ignored the influence of the channel walls, do not capture all the factors affecting the thermotropic properties of the embedded nanocrystals.

AB - Crystallization of organic compounds in nanometer-scale channels of controlled pore glass (CPG) and porous polystyrene (p-PS), the latter prepared by etching of the polylactide (PLA) component of shear-aligned PS-PLA diblock copolymers, produces crystals with dimensions that reflect the size constraints imposed by the channels. The nanoscopic dimensions of the organic crystals embedded in the channels result in a substantial melting point depression compared with the bulk, as demonstrated here for 2,2,3,3,4,4-hexafluoro-1,5-pentanediol (HFPD) and (R)-(+)-3-methyladipic acid (R-MAA). The melting points decreased with decreasing channel diameter, consistent with the increasing surface-area-to-volume ratio of the crystals. Furthermore, at these length scales the latent heat of melting decreased with decreasing crystal size. The melting point depression for both HFPD and R-MAA was greater in p-PS than in CPG, which can only be explained by interactions of the nanocrystals and their corresponding melts with the channel walls. Collectively, these discoveries reveal that simplified descriptions used in previous investigations of embedded crystals, which were limited to porous glass matrixes and ignored the influence of the channel walls, do not capture all the factors affecting the thermotropic properties of the embedded nanocrystals.

UR - http://www.scopus.com/inward/record.url?scp=13444274463&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=13444274463&partnerID=8YFLogxK

U2 - 10.1021/jp045488v

DO - 10.1021/jp045488v

M3 - Article

C2 - 16851108

AN - SCOPUS:13444274463

VL - 109

SP - 1392

EP - 1399

JO - Journal of Physical Chemistry B Materials

JF - Journal of Physical Chemistry B Materials

SN - 1520-6106

IS - 4

ER -