Synthesis and properties of σ-π conjugated porous polymers obtained withMizoroki-Heckreaction of tetra vinyl cyclic siloxane with dibromo fluorene

sigma-pi Conjugated porous polymers were synthesized by the Mizoroki-Heck reaction of cyclic siloxane with vinyl groups, 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane (TVMCTS), and 2,7-dibromo-9,9-dialkylfluorene (RFl) compounds, using a Pd catalyst inN,N-dimethylformamide (DMF) at 100 degrees C. The reactions of TVMCTS in combination with 2,7-dibromo-9,9-dihexylfluorene (HFl), 2,7-dibromo-9,9-dioctylfluorene (OFl), and 2,7-dibromo-9,9-ethylhexylfluorene (EHFl) yielded porous polymers whose morphologies were induced by phase separation during the network formation. The reactions in combination with binary RFl systems, TVMCTS-HFl/OFl, and HFl/EHFl systems, also yielded porous polymers. Scanning electron microscope images showed porous structures, which were composed by connected globules and/or isolated-deformed holes. The long and branching structure of the alkyl side chains in RFl decreased Young's modulus of porous polymers in compression test. The porous polymers showed emission derived from sigma-pi conjugated fluorene units on photo excitation. An increase in monomer concentration in the reaction induced red shifts of the emission bands of the porous polymer due to pi-stacking of the fluorene units. The porous polymers showed relatively high fluorescence quantum yields of about 0.2-0.3. Quantum yield of the porous polymers with HFl decreased with increasing monomer concentration in the reaction systems.