TY - JOUR
T1 - Crystallization-Arrested Viscoelastic Phase Separation in Semiconducting Polymer Gels
AU - He, Jing
AU - Kong, Xiaoqing
AU - Wang, Yuhao
AU - Delaney, Michael
AU - Kalyon, Dilhan M.
AU - Lee, Stephanie S.
N1 - Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/3/8
Y1 - 2019/3/8
N2 - Through a combination of rheological characterization and temperature-variable imaging methods, a novel gelation pathway in dilute solutions of a semiconducting polymer to achieve interconnected, crystalline networks with hierarchical porosity is reported. Upon rapid cooling, solutions of regioregular poly(3-hexylthiophene) in ortho-dichlorobenzene formed thermoreversible gels. Confocal microscopy revealed cooling-induced structural rearrangement to progress through viscoelastic phase separation (VPS), which arrested prematurely during the formation of micron-sized solvent-rich "holes"due to interchain crystallization. Cryogen-based scanning electron microscopy uncovered an interfibrillar network exhibiting nanosized pores. These networks formed to equal gel strengths when a third component, either small molecule phenyl-C61-butyric acid methyl ester or noncrystallizing regiorandom, poly(3-hexylthiophene), was added to the solution. Organic solar cells deposited with active layers from phase-separated solutions displayed 45% higher efficiency compared to reference cells. The demonstrated ability to arrest VPS enables control over the morphology of porous materials for applications ranging from membrane filtration to plastic foam manufacturing.
AB - Through a combination of rheological characterization and temperature-variable imaging methods, a novel gelation pathway in dilute solutions of a semiconducting polymer to achieve interconnected, crystalline networks with hierarchical porosity is reported. Upon rapid cooling, solutions of regioregular poly(3-hexylthiophene) in ortho-dichlorobenzene formed thermoreversible gels. Confocal microscopy revealed cooling-induced structural rearrangement to progress through viscoelastic phase separation (VPS), which arrested prematurely during the formation of micron-sized solvent-rich "holes"due to interchain crystallization. Cryogen-based scanning electron microscopy uncovered an interfibrillar network exhibiting nanosized pores. These networks formed to equal gel strengths when a third component, either small molecule phenyl-C61-butyric acid methyl ester or noncrystallizing regiorandom, poly(3-hexylthiophene), was added to the solution. Organic solar cells deposited with active layers from phase-separated solutions displayed 45% higher efficiency compared to reference cells. The demonstrated ability to arrest VPS enables control over the morphology of porous materials for applications ranging from membrane filtration to plastic foam manufacturing.
KW - confocal microscopy
KW - cryo-SEM
KW - gelation
KW - organic photovoltaics
KW - polymer crystallization
KW - rheology
KW - viscoelastic phase separation
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U2 - 10.1021/acsapm.8b00195
DO - 10.1021/acsapm.8b00195
M3 - Article
AN - SCOPUS:85098417543
VL - 1
SP - 500
EP - 508
JO - ACS Applied Polymer Materials
JF - ACS Applied Polymer Materials
IS - 3
ER -