document: In general, the ion exchange capacity (IEC) is closely related to the proton conductivity of PEMs because the acid functionalities, such as sulfonic acid groups, contribute to the proton conduction in a membrane. Beyond a certain sulfonation degree, PEMs tend to absorb too much water or are even soluble in water, which negatively affect their mechanical resistance and water resistance [17,18]. Therefore, the improvement of proton conductivity using aromatic polymers with moderately adjusted IEC values has been under intense investigation [19–23]. To achieve high proton conductivity with moderate IEC values, the formation of ion channel structures, which enable effective proton conduction, has been studied. In the course of these studies, an ideal morphology has been pursued by microphase separation of segmented block copolymers in which hydrophilic sulfonated polymer segments form an interconnected three-dimensional network responsible for efficient proton transport, while a complementary network of hydrophobic non-sulfonated segments imparts a reinforcing effect, preventing excessive swelling in water and enhancing the mechanical properties. An image of the ideal morphology for PEMs is shown in Fig. 2.
doc_bio_tags: O O O B I I B O O O O O B O O B O O O O O O B I I O O O B O O O B O O O O O B O O O O O B O O O O O B O O O O O O O B O O O O O O B O O B I O O O B O O O O O O O O O B I I O O B O O B I I I I O O B I I O O O O O O O O O O O O O O O O O O O B I I O O B I I I O O O O O O O O B O O O O O O O O O O O O O B I I I I O B I I I O O O O O O O B O O O O O
extractive_keyphrases: aromatic polymers effective proton conduction enhancing the mechanical properties formation of ion channel structures high proton conductivity hydrophilic sulfonated polymer segments iec ion exchange capacity membrane pems preventing excessive swelling in water proton segmented block copolymers sulfonic acid groups water
abstractive_keyphrases: complementary network of hydrophobic non-sulfonated segments hydrophobic non-sulfonated segments improvement of proton conductivity using aromatic polymers with moderately adjusted iec values interconnected three-dimensional network ion channel structures proton conduction proton conductivity proton transport