Polyacetylene (PA) is a symmetric chain of conjugated macromolecule, whose chain symmetry can, however, be broken by external and internal perturbations, generating helically chiral polymers.

• 聚乙炔是链对称的共轭大分子,在内外界的微扰下，其主链的对称性能够被破坏，而产生螺旋手性结构。