Disclosed herein are a polymeric material comprising a plurality of polymeric nanosheets arranged in a layer-by-layer configuration to provide a two-dimensional microporous polymeric material, wherein each of the plurality of polymeric nanosheets is formed from a plurality of ladder-shaped polymers, the ladder-shaped polymers are formed from at least one multivalent monomeric material that has: two or more polymerisable functional groups selected from one or both of acetylene and vinyl functional groups; and a functional group capable of forming a halogen bond with a halogen atom, use of the polymeric material, and a method of manufacturing the polymeric material. Also disclosed herein is a method of adsorbing Li.sup.+ and/or B.sup.3+ ions from an aqueous solution comprising a mixture of ionic species.

Disclosed herein are a polymeric material comprising a plurality of polymeric nanosheets arranged in a layer-by-layer configuration to provide a two-dimensional microporous polymeric material, wherein each of the plurality of polymeric nanosheets is formed from a plurality of ladder-shaped polymers, the ladder-shaped polymers are formed from at least one multivalent monomeric material that has: two or more polymerisable functional groups selected from one or both of acetylene and vinyl functional groups; and a functional group capable of forming a halogen bond with a halogen atom, use of the polymeric material, and a method of manufacturing the polymeric material. Also disclosed herein is a method of adsorbing Li.sup.+ and/or B.sup.3+ ions from an aqueous solution comprising a mixture of ionic species.