Hydrophilic polymers contain polar or charged functional groups, rendering them soluble in water. Within this section, most hydrophilic polymers are grouped by the chemistry of their structure. For example, acrylics include acrylic acid, acrylamide, and maleic anhydride polymers and copolymers. Amine-functional polymers include allylamine, ethyleneimine, oxazoline, and other polymers containing amine groups in their main- or side-chains. Note that polar polymers that are insoluble in water, such as poly(vinylpyridine), are listed in the Hydrophobic Polymers section.