Polyacetylene(PA) is a symmetric chain 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。