Molecular conformations of diblock oligomers H(CH2)(10)(OCH2CH2)(m)OH (m = 2, 4, and 6) in the solid state were studied at high pressures (1-2 GPa) by IR spectroscopy. The oxyethylene chain in the oligomers with m = 2 and 4 assumes the all-trans planar conformation, while that in the oligomer with m = 6 assumes the helical conformation. The stabilized planar structure of the oxyethylene chain at high pressures is explained by increased intermolecular cohesive forces in the alkyl block reinforced by external pressures.