Morphologies of poly(cyclohexadiene) diblock copolymers: Effect of conformational asymmetry

Jimmy W. Mays; Rajeev Kumar; Scott W. Sides; Monojoy Goswami; Bobby G. Sumpter; Kunlun Hong; Xiaodong Wu; Thomas P. Russell; Samuel P. Gido; Apostolos Avgeropoulos; Thodoris Tsoukatos; Nikos Hadjichristidis; Frederick L. Beyer

doi:10.1016/j.polymer.2012.08.047

Morphologies of poly(cyclohexadiene) diblock copolymers: Effect of conformational asymmetry

Jimmy W. Mays, Rajeev Kumar, Scott W. Sides, Monojoy Goswami, Bobby G. Sumpter, Kunlun Hong, Xiaodong Wu, Thomas P. Russell, Samuel P. Gido, Apostolos Avgeropoulos, Thodoris Tsoukatos, Nikos Hadjichristidis, Frederick L. Beyer

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Abstract

Concerted experimental and theoretical investigations have been carried out to understand the microphase separation in diblock copolymer melts containing poly (1,3-cyclohexadiene), PCHD, as one of the constituents. In particular, we have studied diblock copolymer melts containing polystyrene (PS), polybutadiene (PB), and polyisoprene (PI) as the second block. We have systematically varied the ratio of 1,2-/1,4-microstructures of poly (1,3-cyclohexadiene) to tune the conformational asymmetry between the two blocks and characterized the effects of these changes on the morphologies using transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). Our experimental investigations reveal that the melts of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing nearly equal fractions of each component and high percentage of 1,4-microstructures in the PCHD block form cylindrical rather than lamellar morphologies as expected in symmetric diblock copolymers. In contrast, the morphologies of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing PCHD block with higher 1,2-microstructure are found to be disordered at 110 °C. The change in the morphological behavior is in good agreement with our numerical calculations using the random phase approximation and self-consistent field theory for conformationally asymmetric diblock copolymer melts. Also, the effects of composition fluctuations are studied by extending the Brazovskii-Leibler-Fredrickson-Helfand (J. Chem. Phys. 87, 697 (1987)) theory to conformationally asymmetric diblock copolymer melts. These results allow the understanding of the underlying self-assembly process that highlights the importance of the conformational asymmetry in tuning the morphologies in block copolymers.

Original language	English
Pages (from-to)	5155-5162
Number of pages	8
Journal	Polymer
Volume	53
Issue number	22
DOIs	https://doi.org/10.1016/j.polymer.2012.08.047
State	Published - Oct 12 2012

Funding

This work was supported by the Materials Science and Engineering Division, U.S. Department of Energy (DoE), Office of Basic Energy Sciences (BES) under Contract No. DEAC05-00OR22725 with UT-Battelle, LLC, at Oak Ridge National Laboratory (ORNL). Part of the research was done at the Center for Nanophase Materials Sciences, which is sponsored by the Scientific User Facilities Division of DOE . This research used resources of the Oak Ridge Leadership Computing Facility at the ORNL.

Funders	Funder number
Materials Science and Engineering Division
Office of Basic Energy Sciences
U.S. Department of Energy
Basic Energy Sciences

Keywords

Block copolymer
Morphology
Poly(cyclohexadiene)

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10.1016/j.polymer.2012.08.047

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title = "Morphologies of poly(cyclohexadiene) diblock copolymers: Effect of conformational asymmetry",

abstract = "Concerted experimental and theoretical investigations have been carried out to understand the microphase separation in diblock copolymer melts containing poly (1,3-cyclohexadiene), PCHD, as one of the constituents. In particular, we have studied diblock copolymer melts containing polystyrene (PS), polybutadiene (PB), and polyisoprene (PI) as the second block. We have systematically varied the ratio of 1,2-/1,4-microstructures of poly (1,3-cyclohexadiene) to tune the conformational asymmetry between the two blocks and characterized the effects of these changes on the morphologies using transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). Our experimental investigations reveal that the melts of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing nearly equal fractions of each component and high percentage of 1,4-microstructures in the PCHD block form cylindrical rather than lamellar morphologies as expected in symmetric diblock copolymers. In contrast, the morphologies of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing PCHD block with higher 1,2-microstructure are found to be disordered at 110 °C. The change in the morphological behavior is in good agreement with our numerical calculations using the random phase approximation and self-consistent field theory for conformationally asymmetric diblock copolymer melts. Also, the effects of composition fluctuations are studied by extending the Brazovskii-Leibler-Fredrickson-Helfand (J. Chem. Phys. 87, 697 (1987)) theory to conformationally asymmetric diblock copolymer melts. These results allow the understanding of the underlying self-assembly process that highlights the importance of the conformational asymmetry in tuning the morphologies in block copolymers.",

keywords = "Block copolymer, Morphology, Poly(cyclohexadiene)",

author = "Mays, {Jimmy W.} and Rajeev Kumar and Sides, {Scott W.} and Monojoy Goswami and Sumpter, {Bobby G.} and Kunlun Hong and Xiaodong Wu and Russell, {Thomas P.} and Gido, {Samuel P.} and Apostolos Avgeropoulos and Thodoris Tsoukatos and Nikos Hadjichristidis and Beyer, {Frederick L.}",

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T1 - Morphologies of poly(cyclohexadiene) diblock copolymers

T2 - Effect of conformational asymmetry

AU - Mays, Jimmy W.

AU - Kumar, Rajeev

AU - Sides, Scott W.

AU - Goswami, Monojoy

AU - Sumpter, Bobby G.

AU - Hong, Kunlun

AU - Wu, Xiaodong

AU - Russell, Thomas P.

AU - Gido, Samuel P.

AU - Avgeropoulos, Apostolos

AU - Tsoukatos, Thodoris

AU - Hadjichristidis, Nikos

AU - Beyer, Frederick L.

PY - 2012/10/12

Y1 - 2012/10/12

N2 - Concerted experimental and theoretical investigations have been carried out to understand the microphase separation in diblock copolymer melts containing poly (1,3-cyclohexadiene), PCHD, as one of the constituents. In particular, we have studied diblock copolymer melts containing polystyrene (PS), polybutadiene (PB), and polyisoprene (PI) as the second block. We have systematically varied the ratio of 1,2-/1,4-microstructures of poly (1,3-cyclohexadiene) to tune the conformational asymmetry between the two blocks and characterized the effects of these changes on the morphologies using transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). Our experimental investigations reveal that the melts of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing nearly equal fractions of each component and high percentage of 1,4-microstructures in the PCHD block form cylindrical rather than lamellar morphologies as expected in symmetric diblock copolymers. In contrast, the morphologies of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing PCHD block with higher 1,2-microstructure are found to be disordered at 110 °C. The change in the morphological behavior is in good agreement with our numerical calculations using the random phase approximation and self-consistent field theory for conformationally asymmetric diblock copolymer melts. Also, the effects of composition fluctuations are studied by extending the Brazovskii-Leibler-Fredrickson-Helfand (J. Chem. Phys. 87, 697 (1987)) theory to conformationally asymmetric diblock copolymer melts. These results allow the understanding of the underlying self-assembly process that highlights the importance of the conformational asymmetry in tuning the morphologies in block copolymers.

AB - Concerted experimental and theoretical investigations have been carried out to understand the microphase separation in diblock copolymer melts containing poly (1,3-cyclohexadiene), PCHD, as one of the constituents. In particular, we have studied diblock copolymer melts containing polystyrene (PS), polybutadiene (PB), and polyisoprene (PI) as the second block. We have systematically varied the ratio of 1,2-/1,4-microstructures of poly (1,3-cyclohexadiene) to tune the conformational asymmetry between the two blocks and characterized the effects of these changes on the morphologies using transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). Our experimental investigations reveal that the melts of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing nearly equal fractions of each component and high percentage of 1,4-microstructures in the PCHD block form cylindrical rather than lamellar morphologies as expected in symmetric diblock copolymers. In contrast, the morphologies of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing PCHD block with higher 1,2-microstructure are found to be disordered at 110 °C. The change in the morphological behavior is in good agreement with our numerical calculations using the random phase approximation and self-consistent field theory for conformationally asymmetric diblock copolymer melts. Also, the effects of composition fluctuations are studied by extending the Brazovskii-Leibler-Fredrickson-Helfand (J. Chem. Phys. 87, 697 (1987)) theory to conformationally asymmetric diblock copolymer melts. These results allow the understanding of the underlying self-assembly process that highlights the importance of the conformational asymmetry in tuning the morphologies in block copolymers.

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KW - Morphology

KW - Poly(cyclohexadiene)

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Morphologies of poly(cyclohexadiene) diblock copolymers: Effect of conformational asymmetry

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Keywords

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