We have investigated the influence of the flat interface between a silicon single crystal and aqueous polybutadiene-b-poly(ethyleneoxide) solutions on the solutions' isotropic to nematic phase transition (I/N). An I/N pre-transition is induced by the wall at volume fractions of the polymer which are about 15% smaller than required for the phase transition in the bulk. Contrary to theoretical predictions for hard rod fluids and semi-flexible polymer systems this pre-transition is not followed by complete wetting of the interface by the nematic phase upon further increase of the polymer volume fraction.