The thermal and biphasic behaviour is reported for a side-chain smecti
c polyacrylate having a number average molecular weight of 59000g mol(
-1) and a first polydispersity index of 1.9. Evidence is provided for
the existence of smectic Ad and smectic Al mesophases, the former bein
g enantiotropic and the latter monotropic. The biphasic behaviour was
studied by DSC by annealing the polymer inside the apparent biphasic g
ap associated with the smectic Ad-isotropic transition. A biphasic tem
perature range in which isotropic and smectic Ad phases coexist at equ
ilibrium was revealed, and the thermodynamic width of this biphasic re
gion was estimated to be about 2.0 K.