A series of diamine monomers, i.e., 2,2'-bis{4-[3,4,5-tris(n-alkan-1-yloxy)benzoate]}-4,4'-biphenyldiamines containing multiple alkyl side chains, were synthesized in which the length of the alkyl side chains was varied from 5 to 18 carbon atoms. Polyimides were prepared from the diamines and pyromellitic dianhydride (PMDA), 3,3'4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,2'-dibromo-4,4',5,5'-biphenyltetracarboxylic dianhydride (DBBPDA), and 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), respectively, using a one-step method in 1,2-dichlorobenzene or 1-chloronaphthalene. Most of the polymers had good solubility in chlorinated solvents. Several copolyimides were prepared: BPDA, 2,2'-bis(trifluoromethyl)benzidine (PFMB), and C14 and C16 diamines. The solubility of copolyimides was dramatically affected by different monomer addition sequences. The high-molecular-weight polyimides could be solution cast into flexible, tough films except for those based on PMDA. The side chains that contained at least 10 carbon atoms crystallized. The melting points of the crystalline regions increased as the length of the side chains increased. Variable-temperature (VT) solid state C-13 nuclear magnetic resonance (NMR) showed that the polyimide containing C18 side chains crystallized at room temperature. A wide-angle X-ray diffraction (WAXD) study showed that the spacing between the main chains increased as the number of carbon atoms in the side chains increased. The diameter of aggregated backbones was 2.14 nm, indicating several polyimide main chains stacked each other to form supermolecular, nanoscale structures. Three polyimides and one copolyimide were used to prepare alignment layers. The films generated liquid crystal pretilt angles of 6, 9, 90, and 90 degrees, respectively.