Some alternating phenylene-furan units can lead to conformationally locked conjugated polymers. Depending upon the substitution pattern, rigid-rod-like or helical structures can be rationally designed. The presence of helical structure in poly(1,4-(2,3-dialkoxyphenylene)-alt-2,5-furan)s has been demonstrated by adding chiral side chains and by performing circular dichroism measurements. In a good solvent, this polymer exhibits some chiroptical properties which decreases upon aggregation in poor solvents. In contrast, rigid-rod-like poly(1,4-(2,5-di-(S)-2-methylbutoxyphenylene)-alt-2,5-furan) only shows chiroptical properties upon aggregation.