a novel fluorine - containing polymeric compound represented by the general formula -- ch . sub . 2 -- ch . sub . a -- nh . sub . 2 ]}. sub . m - n -- ch . sub . 2 -- ch . sub . a -- nh -- co -- nh -- ch . sub . 2 ). sub . a rf ]}. sub . n , in which rf is a perfluoroalkyl group having 6 to 15 carbon atoms , m is a positive integer in the range from 10 to 1500 , n is a positive integer smaller than 0 . 7 m and a is 0 or 1 , is prepared by the reaction of , when a is 0 , a polyvinylamine of the formula -- ch 2 -- chnh 2 ] m , with an alkyl perfluoroalkanoate of the formula rf -- co -- or , in which r is an alkyl group having 1 to 5 carbon atoms , or , when a is 1 , a polyallylamine of the formula -- ch 2 -- ch ] m , with a perfluoroalkylmethyl isocyanate of the formula rfch 2 -- nco . despite the high fluorine content , the polymer is soluble in at least one kind of organic solvents so that langmuir - blodgett &# 39 ; s films can be prepared from a solution of the polymer . the lb films have an extremely low surface energy and useful as a material for protection and modification of various surfaces .