Preparation and characterization of poly-diacetylene microcrystals

The microcrystals formation process of diacetylene (DCHD) in the reprecipitation method has been investigated by SEM and light scattering. Amorphous DCHD particles were confirmed to be formed first, and then to crystallize. The size control of DCHD monomer microcrystals could be achieved by controlling the size of such amorphous DCHD particles, which depended on the concentration of the injected solution. The solid-state polymerization of DCHD monomer microcrystals was carried out by UV-irradiation, and the size of resulting poly-DCHD microcrystals were 50 nm to 150 nm. The size was unchanged during the solid-state polymerization. By adding SDS in the reprecipitation process, poly-DCHD microcrystal size was further reduced to ca. 15 nm, whose dispersion showed extremely low scattering loss, and expected to be the promising nonlinear optical material.