Synthesis of novel cyclosiloxane monomers containing push-pull moieties and their anionic ring opening polymerization

Area of Science:

• Materials Science
• Polymer Chemistry
• Organic Electronics

Background:

• Development of advanced dielectric materials is crucial for next-generation electronic devices.
• Tailoring polymer structures with specific functional groups can significantly influence their electrical and thermal properties.

Purpose of the Study:

• To synthesize novel tetracyclosiloxane monomers incorporating nitroaniline (NA) or Disperse Red 1 (DR1) push-pull groups.
• To investigate the ring-opening polymerization of these monomers.
• To characterize the resulting polymers' thermal properties and dielectric permittivity.

Main Methods:

• Synthesis of novel tetracyclosiloxane monomers.
• Ring-opening polymerization using tetramethylammonium hydroxide.
• Characterization using spectral methods, gel permeation chromatography, and single crystal X-ray diffraction.
• Analysis of thermal properties via dynamic scanning calorimetry.
• Dielectric permittivity measurements using broadband impedance spectroscopy.

Main Results:

• Polymers with NA groups exhibit a low glass transition temperature (Tg) below room temperature (RT).
• Polymers with DR1 groups melt at 55 °C.
• NA-modified polymers show high permittivity (up to 17.3) at RT due to mobile polar groups.
• DR1-modified polymers have lower permittivity (8.8) at RT but increase to 22 above melting point.
• Polar group mobility significantly impacts dielectric permittivity.

Conclusions:

• Polymers with NA groups are promising for active dielectric materials in actuators, capacitors, and stretchable electronics due to high permittivity and low Tg.
• Polymers with DR1 groups are suitable for nonlinear optical devices, especially above their melting temperature where dipoles become mobile.