NOVELTY - Product comprises a proton conductive polymer membrane comprising a polymer chain having a repeating unit derived from 2,3,7,8-tetramethoxy-10,10-dimethyl-10H-phenoxasiline-4,6-disulfonic acid.    USE - The product comprising proton conductive polymer membrane is useful in a fuel cell.    ADVANTAGE - The product exhibits improved proton conductivity at a low relative humidity. The membrane allows fuel cells to operate at a low relative humidity and reduces the problems associated with cathode flooding, water management and freeze start up, and reduces the cost of operating a fuel cell.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) the 2,3,7,8-tetramethoxy-10,10-dimethyl-10H-phenoxasiline-4,6-disulfonic acid;    (2) a method comprising chlorosulfonating at least one of 2,3,7,8-tetramethoxydibenzo(b,d)furan, 2,3,7,8-tetramethoxyoxanthrene, 2,3,7,8-tetramethoxyphenoxathiine, 2,3,7,8-tetramethoxyphenoxathiine 10,10-dioxide, 2,3,7,8-tetramethoxy-10,10-dimethyl-10H-phenoxasiline or 1,1'-oxybis(3,4-dimethoxybenzene);    (3) a method-I comprising introduce two thiol unit to 1,1'-oxybis(3,4-dimethoxybenzene) followed by oxidation to produce 2,2'-oxybis(4,5-dimethoxybenzenesulfonic acid);    (4) a method-II comprising transforming 2,2'-oxybis(4,5-dimethoxybenzenesulfonyl chloride) into diethyl 2,2'-oxybis (4,5-dimethoxybenzenesulfonate) with triethylamine in ethanol, followed by adding 2 equivalents of tetrabutylammonium iodide or n-butyllithium to 1 equivalent of diethyl 2,2'-oxybis(4,5-dimethoxybenzenesulfonate) during reflux conditions in acetone to produce bis-tetrabutylammonium 2,2'-oxybis(4,5-dimethoxybenzenesulfonic acid) salt;    (5) the 2,2'-oxybis(4,5-dimethoxybenzenesulfonic acid) salt;    (6) a method-III comprising treating 1,1'-oxybis(3,4-dimethoxybenzene) a Charles Mioskowski reagent in the presence of triflic anhydride, followed by the addition of excess triethylamine to produce the intermediate dimethyl 3,3'-(oxybis((4,5-dimethoxybenzene-2,1-diyl)sulfanediyl))dipropanoate, followed by an elimination step by potassium tert-butoxide to produce 2,2'-oxybis(4,5-dimethoxybenzene thiol);    (7) a method-IV of synthesis of an ether with isopropyl groups comprising 1,1-oxybis(4-methoxy-3-(propan-2-yloxy)benzene) by reacting 2-methoxy-phenol with methanesulfonyl chloride and triethylamine, N-bromosuccinimide, lithium diisopropylamide and isopropyl bromide and potassium carbonate to form 4-bromo-2-isopropoxy-1-methoxy-benzene (a), reacting 3-hydroxy-4-methoxy-benzaldehyde with isopropyl bromide, potassium carbonate and dimethylformamide, meta-chloroperoxybenzoic acid and dichloromethane, and potassium carbonate and methanol to form 3-isopropoxy-4-methoxy-phenol (b) and reacting (a) and (b) with sodium hydride, dimethylformamide and copper iodide at 180 degrees C to form 2-isopropoxy-4-(3-isopropoxy-4-methoxy-phenoxy)-1-methoxy-benzene;    (8) a method-V comprising converting diethyl 2,2'-oxybis(5-hydroxy-4-methoxybenzenesulfonate) or diethyl 2,2'-oxybis(4-hydroxy-5-methoxybenzenesulfonate) to bis(N,N,N-tributylbutan-1-aminium) 2,2'-oxybis(5-hydroxy-4-methoxybenzenesulfonate) or bis(N,N,N-tributylbutan-1-aminium) 2,2'-oxybis(4-hydroxy-5-methoxybenzenesulfonate), respectively using tetrabutylammonium iodide;    (9) the bis(M) 1,9-dihydroxy-2,8-dimethoxydibenzo(b,d)furan-4,6-disulfonate;    (10) a method-VI of making a tricyclic monomer comprising bis(M) 1,9-dihydroxy-2,8-dimethoxydibenzo(b,d)furan-4,6-disulfonic acid salt comprising oxidizing diethyl 2,2'-oxybis(4-hydroxy-5-methoxybenzenesulfonate) to produce diethyl 2,2'-oxybis(4-oxy-radical-5-methoxybenzenesulfonate) or diethyl 2,2'-oxybis(3-aryl-radical-5-methoxy-4-oxocyclohexa-1,5-diene-1-sulfonate) and collapsing the same to produce diethyl 1,9-dihydroxy-2,8-dimethoxydibenzo(b,d)furan-4,6-disulfonate;    (11) the diethyl 2,8-dimethoxy-3,7-dioxodibenzo(b,d)furan-9a,9b(3H,7H)-disulfonate; and    (12) a method-VII of making polymerizable tricyclic monomers comprising converting 2,3,6,7-tetramethoxy-biphenylene, 2,3,7,8-tetramethoxydibenzo(b,d)furan, 2,3,7,8-tetramethoxy-dibenzothiophene, 2,3,7,8-tetramethoxydibenzo(b,d)thiophene 5,5-dioxide, or 2,3,7,8-tetramethoxydibenzo(b,d)thiophene 5,5-dioxide to 2,3,6,7-tetramethoxybiphenylene-1,8-disulfonic acid, 2,3,7,8-tetramethoxydibenzo(b,d)furan-4,6-disulfonic acid, 2,3,7,8-tetramethoxydibenzo(b,d)thiophene-4,6-disulfonic acid, 2,3,7,8-tetramethoxydibenzo(b,d)thiophene-4,6-disulfonic acid 5,5-dioxide, or 2,3,7,8-tetramethoxy-5,5-dimethyl-5H-dibenzo(b,d)silole-4,6-disulfonic acid, respectively.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of product.    Fuel cell (10)    Electrolyte layer (12)    Electrode layers (14)    Gas diffusion layers (18)    Bipolar plate (20)    Microporous layer. (22)