Thermal Analysis of Semiconducting Polymer Crystals Free of a Mobile Amorphous Fraction

Ngoc A. Nguyen; Roddel A. Remy; Michael E. Mackay

doi:10.1021/acs.macromol.0c02509

Thermal Analysis of Semiconducting Polymer Crystals Free of a Mobile Amorphous Fraction

Ngoc A. Nguyen, Roddel A. Remy, Michael E. Mackay

Research output: Contribution to journal › Article › peer-review

Abstract

Mobile-amorphous-free crystals of a semiconducting polymer, poly(3-hexyl thiophene) (P3HT), were made via a flow induced crystallization technique to yield crystals that were microns long while the other two dimensions were 6 and 21 nm in size. Thermal analysis revealed a melting point depression that is described by the Gibbs-Thomson (GT) equation resulting in an interpretation that is physically sound. On the contrary, contemporary analysis of the melting enthalpy, which also shows a depression below that for an infinitely sized crystal, yields results that are nonphysical and do not agree with the GT analysis. A simple argument is made to correct this discrepancy, using the first law of thermodynamics, to include the sensible heat of the molten crystal mass required for an extrapolation to the melting enthalpy of an infinitely sized crystal. A satisfactory comparison to the results from the GT equation is now found to reconcile older, literature data to good effect. However, the comparison is not as good for the P3HT crystals made here and believed to be because of the finite size of the crystals in two dimensions coupled with the rather large size of the polymer molecules prohibiting a continuum analysis.

Original language	English (US)
Pages (from-to)	2155-2161
Number of pages	7
Journal	Macromolecules
Volume	54
Issue number	5
DOIs	https://doi.org/10.1021/acs.macromol.0c02509
State	Published - Mar 9 2021
Externally published	Yes

ASJC Scopus subject areas

Organic Chemistry
Polymers and Plastics
Inorganic Chemistry
Materials Chemistry

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10.1021/acs.macromol.0c02509

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title = "Thermal Analysis of Semiconducting Polymer Crystals Free of a Mobile Amorphous Fraction",

abstract = "Mobile-amorphous-free crystals of a semiconducting polymer, poly(3-hexyl thiophene) (P3HT), were made via a flow induced crystallization technique to yield crystals that were microns long while the other two dimensions were 6 and 21 nm in size. Thermal analysis revealed a melting point depression that is described by the Gibbs-Thomson (GT) equation resulting in an interpretation that is physically sound. On the contrary, contemporary analysis of the melting enthalpy, which also shows a depression below that for an infinitely sized crystal, yields results that are nonphysical and do not agree with the GT analysis. A simple argument is made to correct this discrepancy, using the first law of thermodynamics, to include the sensible heat of the molten crystal mass required for an extrapolation to the melting enthalpy of an infinitely sized crystal. A satisfactory comparison to the results from the GT equation is now found to reconcile older, literature data to good effect. However, the comparison is not as good for the P3HT crystals made here and believed to be because of the finite size of the crystals in two dimensions coupled with the rather large size of the polymer molecules prohibiting a continuum analysis.",

author = "Nguyen, {Ngoc A.} and Remy, {Roddel A.} and Mackay, {Michael E.}",

note = "Funding Information: We would like to thank the University of Delaware for the funding through the Department of Materials Science and Engineering, the National Institute of Standards and Technology through the award 70NANB10H256 through the Center for Neutron Science at the University of Delaware, and the W.M. Keck Electron Microscopy Facility at University of Delaware. We thank Prof. Chaoying Ni for assistance with selected area electron diffraction characterization. We also thank Dr. Jeffrey S. Meth at the DuPont Experimental Station for access to the helium pycnometer. Publisher Copyright: {\textcopyright} 2021 American Chemical Society.",

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AU - Nguyen, Ngoc A.

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AU - Mackay, Michael E.

N1 - Funding Information: We would like to thank the University of Delaware for the funding through the Department of Materials Science and Engineering, the National Institute of Standards and Technology through the award 70NANB10H256 through the Center for Neutron Science at the University of Delaware, and the W.M. Keck Electron Microscopy Facility at University of Delaware. We thank Prof. Chaoying Ni for assistance with selected area electron diffraction characterization. We also thank Dr. Jeffrey S. Meth at the DuPont Experimental Station for access to the helium pycnometer. Publisher Copyright: © 2021 American Chemical Society.

PY - 2021/3/9

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N2 - Mobile-amorphous-free crystals of a semiconducting polymer, poly(3-hexyl thiophene) (P3HT), were made via a flow induced crystallization technique to yield crystals that were microns long while the other two dimensions were 6 and 21 nm in size. Thermal analysis revealed a melting point depression that is described by the Gibbs-Thomson (GT) equation resulting in an interpretation that is physically sound. On the contrary, contemporary analysis of the melting enthalpy, which also shows a depression below that for an infinitely sized crystal, yields results that are nonphysical and do not agree with the GT analysis. A simple argument is made to correct this discrepancy, using the first law of thermodynamics, to include the sensible heat of the molten crystal mass required for an extrapolation to the melting enthalpy of an infinitely sized crystal. A satisfactory comparison to the results from the GT equation is now found to reconcile older, literature data to good effect. However, the comparison is not as good for the P3HT crystals made here and believed to be because of the finite size of the crystals in two dimensions coupled with the rather large size of the polymer molecules prohibiting a continuum analysis.

AB - Mobile-amorphous-free crystals of a semiconducting polymer, poly(3-hexyl thiophene) (P3HT), were made via a flow induced crystallization technique to yield crystals that were microns long while the other two dimensions were 6 and 21 nm in size. Thermal analysis revealed a melting point depression that is described by the Gibbs-Thomson (GT) equation resulting in an interpretation that is physically sound. On the contrary, contemporary analysis of the melting enthalpy, which also shows a depression below that for an infinitely sized crystal, yields results that are nonphysical and do not agree with the GT analysis. A simple argument is made to correct this discrepancy, using the first law of thermodynamics, to include the sensible heat of the molten crystal mass required for an extrapolation to the melting enthalpy of an infinitely sized crystal. A satisfactory comparison to the results from the GT equation is now found to reconcile older, literature data to good effect. However, the comparison is not as good for the P3HT crystals made here and believed to be because of the finite size of the crystals in two dimensions coupled with the rather large size of the polymer molecules prohibiting a continuum analysis.

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Thermal Analysis of Semiconducting Polymer Crystals Free of a Mobile Amorphous Fraction

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