Langmuir Blodgett ultrathin membrane of polyfumarate

A Langmuir-Blodgett ultrathin membrane having one or more monomolecular layers, each layer including a uniform molecluar orientation, the membrane constituted of polyfumarate having a degree of polymerization of 20 to 10,000 and obtained by polymerization fumarate represented by the general formula:

• ##STR4## wherein R.sub.1 and R.sub.2 represent the same or different groups and at least one of R.sub.1 and R.sub.2 represents a hydrocarbon group selected from the group consisting of a branched alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a substituted alkyl group having 2 to 6 carbon atoms and containing a ring structure substituent having 3 to 14 carbon atoms, and a substituted cycloaklyl group having 3 to 10 carbon atoms and containing a second ring structure substituent having 3 to 14 carbon atoms;
• trifluoromethyl, pentafluoroethyl, heptafluoro-n-propyl, or a fluorine-substituted hydrocarbon group obtained by substituted at least one or hydrogen atoms of said hydrocarbon group with a fluorine atom;
• and herero atom-containing hydrocarbon group containing in said hydrocarbon group a herero atom selected from the group consisting of nitrogen, oxygen, phosphorus and sulfur atoms and not containing mobile hydrogen atom or atoms;
• or an organosilyl group, an organosilylalkyl group, an organosiloxanyl group, an organosiloxanylalkyl group, an organosiloxanylsilylalkyl group or an organosiloxanyloxysilylalkyl group, each having 1 to 8 silicon atoms.