Acetylenic monomers undergo aqueous suspension polymerization providing particles constructed by helical substituted polyacetylene. Different from suspension polymerization of vinyl monomers, a cosolvent is indispensable to dissolve Rh catalyst and solid acetylenic monomers. The cosolvent is found to play essential roles in monomers' polymerization and the particles' formation. To systemically explore the effects of cosolvents, three monomers, M1 (achiral, liquid), M2 (achiral, solid), and M3 (chiral, solid), and six cosolvents (divided into two groups by their miscibility with water) are used for performing suspension polymerization in aqueous media at 30 degrees C, with Rh+ B- (C6H5)(4) as catalyst and polyvinylpyrrolidone as stabilizer. FTIR spectra and gel permeation chromatography confirm the occurrence of polymerization. Raman spectra demonstrate the high cis contents of the polymer chains. Scanning electron microscope images show that the polymer particles obtained under optimal conditions are in spherical morphology. Circular dichroism and UV-vis spectroscopy demonstrate the helical structures of the polymer chains forming the chiral particles. Dynamic light scattering characterization is carried out to characterize the nanoparticles. The type and amount of the cosolvent affect the polymerization remarkably. Cosolvents with higher polarity lead to smaller polymer particles, while lower polar cosolvents provide larger ones. (C) 2017 Wiley Periodicals, Inc.