We present an analysis of the thermodynamic properties of chain molecules f
ormed from Yukawa segments using the statistical associating fluid theory w
ith interactions of variable range (SAFT-VR) and the high-temperature expan
sion of the mean-spherical solution (MSA-HTE) to the Ornstein-Zernike equat
ion for a simple Yukawa fluid. The SAFT-VR expressions derived previously f
or this system allow the MSA-HTE equation of state to be reformulated in te
rms of first-order perturbation quantities, thus improving its accuracy. Fu
rthermore, the MSA-HTE solution provides a full theoretical derivation of t
he perturbation theory used in SAFT-VR, together with a completely analytic
al equation of state for chain molecules composed of segments which interac
t via the Yukawa potential. (C) 1999 American Institute of Physics. [S0021-
9606(99)50242-0].