A series of“hairy-rod”polyimides,BBPA(n),with multiple alkyl side chains was prepared from 3,3’,4,4’-biphenyltetracarboxylic dianhydride(BPDA)and 4,4’-biphenyldiamine substituted in the 2,2’-positions with benzoate,whichwas substituted in the 3,4,5-positions with ether side chains of varying lengths.The number of the methylene units,n,inthese alkyl side chains were in even numbers ranging from 8 to 18.Combining techniques of one-dimensional(1D)and 2Dwide angle x-ray diffraction,1D small angle X-ray scattering,differential scanning calorimetry experiments,it was found thatthis series of“hairy-rod”polyimides possess a micro-phase separation between the backbones and side chains.This led to theformation of ordered structures in two different length scales,of which both are hexagonal packing:one is attributed to thealkyl side chains on the sub-nanometer scale,and another is for the whole polymer chains on the nanometer scale.Thedevelopment of the hexagonal structure on the sub-nanometer scale was critically dependent upon the lengths of the alkylside chains.Three relaxation processes were captured by dynamic mechanical analysis,i.e.,segmental motion of thebackbones,α,the melting of the side chain crystals,β_1,which exits only for the materials with longer side chains(n=18,16);and the subglass relaxation of side chains,β_2.The peak relaxation temperature of the αprocess decreased withincreasing the length of side chains,while the one of the β_2 process increased.The activation energy of the αrelaxation wasrelatively independent on the length of side chain,whereas,β_2 process showed the increasing of activation energy withincreasing the length of side chains. A series of “hairy-rod” polyimides, BBPA (n), with multiple alkyl side chains was prepared from 3,3 ’, 4,4’-biphenyltetracarboxylic dianhydride (BPDA) and 4,4’-biphenyldiamine substituted in the 2, 2’-positions with benzoate, which was substituted in the 3,4,5-positions with ether side chains of varying lengths.The number of the methylene units, n, inthese alkyl side chains were in even numbers ranging from 8 to 18. Combining techniques of one-dimensional (1D) and 2D wide angle x-ray diffraction, 1D small angle X-ray scattering, differential scanning calorimetry experiments, it was found that that series of “hairy-rod” polyimides possess a micro-phase separation between the backbones and side chains. This led to the formation of ordered structures in two different length scales, of which both are hexagonal packing: one is attributed to the alkyl side chains on the sub-nanometer scale, and another is for the whole polymer chains on the nanometer scale The development of the hexagonal structure on the sub-nano meter scale was critically dependent upon the lengths of the alkylside chains. Th relaxation processes were captured by dynamic mechanical analysis, ie, segmental motion of thebackbones, α, the melting of the side chain crystals, β_1, which exits only for the materials with longer side chains (n ​​= 18,16); and the subglass relaxation of side chains, β_2. peak relaxation temperature of the αprocess decreased withincreasing the length of side chains, while the one of the β_2 process increased. activation energy of the αrelaxation wasrelatively independent on the length of side chain, while, β_2 process showed the increasing of activation energy withincreasing the length of side chains.