The synthesis of new chiral side-chain liquid-crystalline polysiloxanes containing p-(allyoxy)benzoxy-p-chlorophenyl (ABCH) as mesogenic units and undecylenic acid menthol ester (UM) as chiral nonmesogenic units is presented. The chemical structures of monomers and polymers are confirmed by IR spectroscopy. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are used to measure thermal properties of those polymers. Mesogenic properties are characterized by polarized optical microscope (POM), DSC, and small-angle X-ray diffraction. Analytic results revealed that polymers P-0-P-6 are thermotropic liquid-crystalline polymers with low glass transition; Polymers P-2-P-6 exhibit chiral smectic liquid-crystalline properties with marble texture, optical rotation, and a sharp reflection at low angles in X-ray diffraction; polymers P-0, P-1 only exhibit smectic liquid-crystalline properties without chirality; and P-7 only exhibits chirality without liquid-crystalline properties. All the polymers exhibit good thermal stability with temperature of 5% mass loss over 297degreesC. (C) 2003 Wiley Periodicals, Inc.