Based on side-chain "Jacketing" effect, a series of main-chain/side-chain liquid crystalline polymers (MCSCLCPs) with different lengths of alkyl tail, poly (2,5-bis {[6-(4-alkoxy-4'-oxybiphenyl)-6-hexyl] oxycarbonyl} styrene) (denoted as Pm, m represents the number of carbons in the alkyl tails and m = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.) were synthesized through radical polymerization. Their phase structures were investigated using combined techniques, such as polarized optical microscope (POM), differential scanning calorimetry (DSC), one- and two-dimensional wide-angle X-ray diffraction (1D- and 2D-WAXD) and grazing-incidence wide angle X-ray scattering (GI-WAXS). It has been identified that the phase structure of Pms is strongly dependent on the length of alkyl tail. Pms (m <= 4) with short alkyl tail exhibit double ordered structure on the nanometer and subnanometer scales. Pms (m >= 5) with lengthened alkyl tail form typical smectic C phase. Furthermore, GI-WAXS result reveals that both smectic and hierarchically ordered structure can form preferred orientation on the naked silicon wafer because of the homeotropic property of the side-chain mesogens. (C) 2018 Elsevier Ltd. All rights reserved.