Polynorbornene-based polycations

A method of synthesizing a multiblock, ammonium-functionalized norbornene copolymer comprising:

• performing a controlled vinyl addition polymerization in the presence of a metal catalyst of a first norbornene monomer substituted with a first alkyl group and at least a second norborene monomer substituted with a second alkyl group by adding a predetermined amount of the first norborene monomer and a predetermined amount of the second norbornene monomer sequentially to the reaction to form blocks of an intermediate norbornene multiblock copolymer, the second alkyl group comprising a substituent which undergoes a substitution reaction with a tertiary amine precursor of an ammonium cationic group, and reacting the tertiary amine precursor for the ammonium cationic group with the intermediate norbornene multiblock copolymer to form the multiblock, ammonium-functionalized norbornene copolymer, wherein the first alkyl group is a C1-C20 alkyl group and the second alkyl group is a C1-C20, and wherein the multiblock, ammonium-functionalized norbornene copolymer comprises an odd number of blocks and wherein a first block and a last block of the multiblock, ammonium-functionalized norborene copolymer are formed from the first monomer.

A membrane formed from solution casting of a multiblock, ammonium-functionalized norbornene copolymer formed by a process comprising:

• performing a controlled vinyl addition polymerization in the presence of a metal catalyst of a first norbornene monomer substituted with a first alkyl group and at least a second norbornene monomer substituted with a second alkyl group by adding a predetermined amount of the first norbornene monomer and a predetermined amount of the second norbornene monomer sequentially to the reaction to form blocks of an intermediate norbornene multiblock copolymer, the second alkyl group comprising a substituent which undergoes a substitution reaction with a tertiary precursor of an ammonium cationic group, and reacting the tertiary precursor for the ammonium cationic group with the intermediate norborene multiblock copolymer to form the multiblock, ammonium-functionalized norbornene copolymer, wherein the first alkyl group is a C1-C20 alkyl group and the second alkyl group is a C1-C20 alkyl group, and wherein the multiblock, ammonium-functionalized norbornene copolymer comprises an odd number of blocks and wherein a first block and a last block of the multiblock, ammonium-functionalized norbornene copolymer are formed from the first norbornene monomer.