(US5795496-A)      Preparation of a proton conducting polymer film comprises: (i) treating a sulphonic acid polymer material to enhance its proton conducting characteristics; and (ii) further treating in such a way as to link together some but not all of the proton carrying elements to form a denser but still stable membrane.    Also claimed are: (A) a proton-conducting polymer film where the crosslinked sulphonate containing surface has a higher crosslinking than the opposing surface; (B) a fuel cell electrode/membrane assembly (10) comprising an oxidation allowing anode material (14) attached to the above proton conducting polymer membrane material (18) attached to a reduction allowing cathode (16); and (C) preparation of an asymmetric proton-conducting polymer film comprising selectively sulphonating the polymer material and then partially crosslinking some of the sulphonate groups so that they will not conduct protons.    USE -   Used in a methanol based oxidation/reduction fuel cell (claimed). It is also used to limit fuel crossover in a methanol fuel cell by separating the anode and cathode (claimed).    ADVANTAGE -   Occluding of methanol is carried out by limiting a size of free volumes in the proton conducting membrane (claimed). The film has low methanol permeability but high proton conductivity and is made from inexpensive, readily available materials. These materials are stable at high temperatures.    (EP870340-A1)      Preparation of a proton conducting polymer film comprises: (i) treating a sulphonic acid polymer material to enhance its proton conducting characteristics; and (ii) further treating in such a way as to link together some but not all of the proton carrying elements to form a denser but still stable membrane.    Also claimed are: (A) a proton-conducting polymer film where the crosslinked sulphonate containing surface has a higher crosslinking than the opposing surface; (B) a fuel cell electrode/membrane assembly (10) comprising an oxidation allowing anode material (14) attached to the above proton conducting polymer membrane material (18) attached to a reduction allowing cathode (16); and (C) preparation of an asymmetric proton-conducting polymer film comprising selectively sulphonating the polymer material and then partially crosslinking some of the sulphonate groups so that they will not conduct protons.    USE -   Used in a methanol based oxidation/reduction fuel cell (claimed). It is also used to limit fuel crossover in a methanol fuel cell by separating the anode and cathode (claimed).    ADVANTAGE -   Occluding of methanol is carried out by limiting a size of free volumes in the proton conducting membrane (claimed). The film has low methanol permeability but high proton conductivity and is made from inexpensive, readily available materials. These materials are stable at high temperatures.    (JP2000501223-W)      Preparation of a proton conducting polymer film comprises: (i) treating a sulphonic acid polymer material to enhance its proton conducting characteristics; and (ii) further treating in such a way as to link together some but not all of the proton carrying elements to form a denser but still stable membrane.    Also claimed are: (A) a proton-conducting polymer film where the crosslinked sulphonate containing surface has a higher crosslinking than the opposing surface; (B) a fuel cell electrode/membrane assembly (10) comprising an oxidation allowing anode material (14) attached to the above proton conducting polymer membrane material (18) attached to a reduction allowing cathode (16); and (C) preparation of an asymmetric proton-conducting polymer film comprising selectively sulphonating the polymer material and then partially crosslinking some of the sulphonate groups so that they will not conduct protons.    USE -   Used in a methanol based oxidation/reduction fuel cell (claimed). It is also used to limit fuel crossover in a methanol fuel cell by separating the anode and cathode (claimed).    ADVANTAGE -   Occluding of methanol is carried out by limiting a size of free volumes in the proton conducting membrane (claimed). The film has low methanol permeability but high proton conductivity and is made from inexpensive, readily available materials. These materials are stable at high temperatures.