The present invention relates to the use of a compound having the formula (I) wherein: n represents an integer varying from 720 to 6 200, and i varies from 1 to n, R.sub.i represents in particular OH, or a group of the formula (III) wherein k represents an integer varying from 1 to 17, and R'.sub.i represents a linear or branched alkyl chain comprising p carbon atoms, wherein p is an integer varying from 1 to 17, with the proviso that k+p is not greater than 28, and preferably not greater than 20, and wherein at least one R.sub.i group represents a group of formula (III), for the preparation of a viscoelastic composition.