Controlled Handedness of Twisted Lamellae in Banded Spherulites of Isotactic Poly(2-vinylpyridine) as Induced by Chiral Dopants

Abstract

Herein, we suggest a unique approach to control the handedness of twisted lamellae in banded spherulites of a stereoregular polymer, isotactic poly(2-vinylpyridine) (iP2VP). When (R)- or (S)-hexahydromandelic acid (HMA), which can associate with iP2VP, was introduced as a chiral dopant, mirror-image CD spectra in the complex systems showed induced circular dichroism (ICD) of the iP2VP by chiral HMA. Banded spherulites resulting from lamellar twisting due to the imbalanced stresses at the opposite folding surfaces could be formed by crystallization of the iP2VP/HMA complexes, which had a crystalline structure similar to that of neat iP2VP. A preferential sense of the twisted crystalline lamellae was found in the iP2VP/HMA complex, thus suggesting homochiral evolution from conformational to hierarchical chirality.