Results from molecular dynamics simulations of isolated poly(dialkylsi1oxane) chains are analyzed with emphasis on the conformational dynamics of a fragment of five repeat units, in which the alkyl group is tert-butyl. This fragment furnishes a typical example of a chain in which the bulky substituents restrict to a considerable extent the rotational motions of the backbone, which otherwise enjoys a high degree of flexibility. The rotational motions of the bonds flanking the oxygen atom are observed to be strongly correlated the main mechanism of relaxation in the time range of picoseconds is the coupled counterro- tations of those adjacent bonds. Examination of the molecular dynamics trajectories over much longer time scales, such as tenths of nanoseconds, reveals correlations between the rotational motions of neighboring repeat units, causing a relatively long-range coupling of backbone bonds along the chains, mainly between bonds i and i + 3. The orientational motion of the pair of bonds flanking the oxygen atom is analyzed within the framework of the dynamic rotational isomeric state formalism. In a recent work, molecular dynamics (MD) simulations were employed for a comparative study of the conforma- tional statistics and unperturbed dimensions of a series of poly(dialkylsi1oxane) (PDAS) chains, of the general for- mula CH30(SiRzO),CH3, where x: is the number of repeat units and R 5 CmHZm+l.l In the present work, the con- formational dynamics of the same class of chains, with methyl, ethyl, propyl, butyl, isopropyl, isobutyl, and tert- butyl side groups, is considered, with special emphasis on poly(di-tert-butylsiloxane) (PDTBS), the member of the family which is distinguished by the strong correlations between neighboring bond rotations. One of the main aspects of PDAS conformational statistics is the strong inderdependence of the rotational states of the pair of bonds centered about the oxygen atom, which is evident in the time-averaged probabilities for different pairs of values of the dihedral angles at these bonds. No distinct correlation between the states of the bonds flanking the Si atom is apparent, in the time- averaged probabilities for this pair of bonds. The inter- dependence of the dihedral angles #i and 4i+1 associated with the respective bonds of type Si-0 and 0-Si becomes increasingly pronounced with increasing size of the side chains symmetrically attached to the Si atoms. Among the series of disubstituted polysiloxanes investigated by MD simulations, PDTBS presents the example with the bulkiest side groups. The probability distribution surface P(di,di+l) obtained as a function of the torsional angles c$~ and &+I, with a methoxy-terminated fragment of x = 5 repeat units, exhibits well-defined sequences of ridges and valleys, as a consequence of the strong coupling of the two dihedral angles. All members of the PDAS series have an intrinsically flexible backbone, as a consequence of$he long Si-0 bond, the lower barrier height for the intrinsic torsional potential at this bond, the absence of Substituents at the oxygen atom, the large mean value of the Si-0-Si angle, and the unusually small force constant for bending at Si-0-Si.