Conjugated Copolymers That Shouldn't Be.

Area of Science:

• Materials Science
• Polymer Chemistry
• Organic Electronics

Background:

• Cage silsesquioxanes (SQs) are explored as structural units in hybrid polymers due to their defined structures and properties.
• Previous research focused on the physical and mechanical benefits of incorporating SQs into polymer backbones.

Purpose of the Study:

• To investigate the photophysical properties of copolymers derived from divinyl double decker (DD) SQs and vinyl-ladder (LL) SQs.
• To identify minimal SQ structures that facilitate extended conjugation and unusual electronic behavior.

Main Methods:

• Synthesis of copolymers using divinyl double decker (DD) SQs and vinyl-ladder (LL) SQs.
• Heck catalyzed co-polymerization with bromo-aromatic compounds.
• Photophysical characterization including emission spectroscopy.
• Investigation of charge transfer properties with F4TCNQ dopant.

Main Results:

• Copolymers from vinylDDvinyl SQs showed significant emission red-shifts compared to model compounds.
• Oligomers from vinyl-LL-vinyl SQs exhibited even larger red-shifts (30-60 nm) despite lacking a complete cage structure.
• Evidence of unconventional conjugation and apparent integer charge transfer (ICT) was observed in LL-based copolymers.

Conclusions:

• The study reveals unconventional conjugation pathways in silsesquioxane-based copolymers.
• The observed red-shifts and ICT suggest potential applications in p-type doped organic/inorganic semiconductors.