Size-Controlled Synthesis of Soluble-Conjugated Polymeric Nanoparticles in Dendritic Mesoporous Silica Nanospheres

A size-controlled method has been exploited to synthesize 20 kinds of soluble-conjugated polymeric nanoparticles (SCPNs) through cross-coupling polymerizations between various combinations of symmetrical multifunctional monomers (A(x)+B-y, x > 2, y >= 2). Unlike the classical polycondensation of these kinds of monomers where infinite polymer networks and insoluble polymeric products are typically formed, this confined polymerization in palladium nanoparticles-loaded dendritic mesoporous silica nanospheres produced SCPNs with good to high yields, narrow particle size distribution, and high solubility in common organic solvents. The controlled size of SCPNs characterized with gel permeation chromatography shows narrow distribution and various molecular weight ranging from 2164 to 14 234 Da, transmission electron microscopy and dynamic light scattering analyses range from 5 to 15 nm, suggesting the confined polymerization occurring inside of the mesopores. By simply adjusting the monomer structure and selecting an appropriate cross-coupling polymerization method among Suzuki, Stille, Sonogashira, and direct arylation polymerizations, the obtained SCPNs show bright fluorescence emission varying from blue to red. The SCPNs with long alkyl chain substituents in monomer units show good processability and smooth polymer films are formed by the simple spin-casting method. The repeatable and straightforward synthesis of SCPNs endows them with wide application prospects in light-emission, fluorescence sensing, and bioimaging.