The effect of side groups on rheological properties of different polysilanes in solution phase is investigated and correlated, with radial uniformity of estimated thickness of wet films. The polymethylphenylsilane homopolymer has shear rate-dependent flow properties in the interval 0.2-0.8 s-1 and relaxation time of 0.53 s. This behavior is changed for the copolymer containing methylphenylsilylene units, which becomes less sensitive to shear deformation as a result of chain reduced mobility, with the highest relaxation time of 1.54 s and flow activation energy of 27.08 kJ/mol, combined with the smallest deviation from constant viscosity (~0.02 Pa·s). Such Newtonian flow leads to higher uniformity of the wet film thickness profile alongthe radial position of the spin-coating wafer, comparatively with the other polysilane solutions. Higher spinning times (>60 s) and lower spinning speeds (<590 rpm) are also favorable, to obtain polysilane films with constant thickness. Molecular modeling was performed to investigate polysilane conformation in solution, and its interaction with toluene molecules. The studied polymer solutions have slightly higher work of adhesion to indium tin oxide, and polyethylene terephthalate (around 143 mN/m) substrates, in regard with glass and silicon (around 140 mN/m).