A novel biphasie behavior is detected by thermal analysis and polarizing microscopy in the polyacrylates [CH 2 −(CH(CO 2 R)] n R=(CH 2 ) 6 −O−Ph−N=N−Ph−OR 1 Ri=C 5 H 11 , C 2 H 5 ). Upon annealing these polymers at different temperatures inside the biphasis gap associated to their nematic-isotropic transition, the two coexisting phases separate and afterwards undergo distinct thermal transitions including the isotropic-nematic and nematic-smectic transitions