3

5-Dialino benzanie-4’-diphenyl ester was synthesized and a novel liquid crystalline side-chain in-situsdf-reinforced PI film material has been achieved from co-condensation of 3．5-diamino benzonic-4’-diphenyl ester

3

3’-4

4'-oxydiphthalic anhydride (ODPA) and 4

4'-oxydianiline (ODA)．The properties of polyimides were characterized by DSC

TGA

WAXD and polanrized optical microscopy respectively．The results indicate that the properties of PIs with mesogenic units

such as molecular weight

solubility

thermal stabihty and tensile strength depend strongly on the content of mesogenic units．The molecular weight decreased and the solubility increased with the increase of mesogemc units’level．Due to the in-situ self-reinforcement of LC side-chains

the mechanical properties of PIs were greatly enhanced

for example

the maximum improvement of tensile strength and modulus reach 270％ and 300％．respectively．TGA study indicates that the 5％ weight loss temperature of PIs excess 520℃．Under polarized optical microscopy

these PIs exhibit LC behaviors in a high temperature range and exhibit nematie phase．Co-polymerization and introduction of side-chain mesogenic units decrease the regularity and syrametry of main-chain

so the side-chain liquid crystalline PIs also exhibit good solubility．