Nanoscale control over phase separation in conjugated polymer blends using mesoporous silica spheres

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Conjugated polymers are crucial for organic electronics.
• Controlling polymer blend morphology at the nanoscale is challenging but vital for device performance.

Purpose of the Study:

• To develop a method for preparing blended conjugated polymer microparticles with controlled nanoscale phase separation.
• To investigate the effect of blending order on the morphology and properties of Poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(furfuryl alcohol) (PFA) blends.

Main Methods:

• Utilized mesoporous silica spheres as templates for sequential infiltration-polymerization of PEDOT and PFA.
• Characterized the resulting polymer microparticles using electron microscopy (SEM, TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray microanalysis (EDX), and nitrogen adsorption.
• Removed the silica template using hydrofluoric acid etching and measured electrical conductivity.

Main Results:

• The silica template successfully guided the formation of blended polymer microparticles with retained spherical morphology.
• Sequential blending order significantly impacted phase separation; PEDOT-first blending resulted in nanoscale contact, while PFA-first led to macrophase separation.
• Blended microparticles exhibited conductivity above the percolation threshold, indicating effective nanoscale phase mixing.

Conclusions:

• The mesoporous silica templating method allows for engineered nanoscale phase separation in conjugated polymer blends.
• Controlling the order of polymer addition is critical for achieving desired blend morphology and properties.
• This approach offers potential for enhancing organic electronic device architecture and performance.