A monomer represented by the structural formula: Z-CHR 3 -Ar-CHR 4 -Z' wherein -Z and -Z' are independently selected from the group consisting of halogen, pseudo-halogen selected from the group consisting of trifluoromethylmethanesulfonyl, para-toluenesulfonyl and methanesulfonyl, -S R" and -SC R 0 with the proviso that -Z and -Z' are not simultaneously halogen or pseudo-halogen, wherein Ar is selected from the group consisting of substituted and non-substituted triptycenylene, substituted and non-substituted pentiptycenylene and substituted and non-substituted iptycenylene, wherein the substituents on the substituted triptycenylene, pentiptycenylene or iptycenylene can be: - linear or branched C 1-20 alkyl and C 1-20 alkoxy and wherein, if the main chain of said linear or branched C 1-20 alkyl or C 1-20 alkoxy includes at least 3 carbon atoms, one or more non-adjacent CH or CH 2 divalent groups of said linear or branched C 1-20 alkyl and C 1-20 alkoxy may independently be replaced by O, S, C(=O), C(=O)O, OC(=O), NH, N-C 1-4 alkyl or NC(=O) and/or wherein one or more hydrogens may be each independently replaced by a substituent selected from the group consisting of fluoro, chloro, aryl, aryloxy, COOR*, SO 3 R*, CN, and NO 2 wherein R* is selected from the group consisting of C 1-20 alkyl, C 2-20 alkenyl and aryl, - C 1 -C 20 alkylsulphate and salts thereof, - oligo- or poly(ethylene oxide), - a phenyl group or a benzyl group, wherein R 0 is selected from the group consisting of -NR 1 R 2; C 1 -C 20 alkyloxy; aryloxy; alkyl; aryl; alkylaryl; arylalkyl; thio C 1-7 alkyl; thio C 3-10 cycloalkyl; arylthio; arylalkylthio; thioheterocyclic ether; ester of the formula COO-alkyl; carboxylic acid and heterocyclyl, wherein R 1 and R 2 are either independently selected from the group consisting of C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, aryl, C 1-4 alkyl-aryl, aryl-C 1-4 alkyl and heterocyclyl, or R 1 and R 2 are linked together to form a cycle comprising 4 to 8 carbons, wherein R 3 and R 4 are selected from the group consisting of hydrogen, C 1 -C 20 -alkyl group, a cyclic C 3 -C 20 -alkyl group, aryl groups, alkylaryl groups, arylalkyl groups and heterocyclic groups and wherein R" is selected from the group consisting of C 1 -C 10 alkyl and aryl, and wherein aryl is optionally substituted with one or more substituents selected from the group consisting of halogen, amino, nitro, hydroxyl and sulfhydryl. - linear or branched C 1-20 alkyl and C 1-20 alkoxy and wherein, if the main chain of said linear or branched C 1-20 alkyl or C 1-20 alkoxy includes at least 3 carbon atoms, one or more non-adjacent CH or CH 2 divalent groups of said linear or branched C 1-20 alkyl and C 1-20 alkoxy may independently be replaced by O, S, C(=O), C(=O)O, OC(=O), NH, N-C 1-4 alkyl or NC(=O) and/or wherein one or more hydrogens may be each independently replaced by a substituent selected from the group consisting of fluoro, chloro, aryl, aryloxy, COOR*, SO 3 R*, CN, and NO 2 wherein R* is selected from the group consisting of C 1-20 alkyl, C 2-20 alkenyl and aryl, - C 1 -C 20 alkylsulphate and salts thereof, - oligo- or poly(ethylene oxide), - a phenyl group or a benzyl group,