PURPOSE: To obtain a method for producing a light-responsive polymer material excellent in durability in repeated reversible changes from hydrophilic to hydrophobic due to light irradiation by introducing a specific compd. as light- responsive groups into side chains of a polymer or by dispersing the compd. in a polymer.

CONSTITUTION: A compd. having a light-responsive group is introduced into side chains of a polymer or dispersed in a polymer, giving a light-responsive polymer material. The reversible change of the surface of the material from hydrophilic to hydrophobic can be controlled by utilizing the isomerization due to proton transfer of the light-responsive groups caused by light irradiation or heaing. Examples of the compd. are salicylideneaniline derivs. of formulas I, II, and III and a nitrobenzene deriv. of formula IV. The material is used in printing or copying with a printer, a copying machine, a facsimile, etc. After the material is applied to a substrate and treated with a thermal pulse due to an image signal under irradiation with light to selectively convert parts of the polymer surface into hydrophobic (or hydrophilic) parts, a hydrophobic (or hydrophilic) ink is attached to the parts and transferred to a printing or copying material.