Abstract: Compositions and methods for treating substrates, such as fibrous materials, are disclosed. Such compositions and methods can be used to impart or maintain a level of oil repellency and/or water repellency in fibrous substrates such as paper-based materials and/or textiles. In general, such compositions can utilize a copolymer having a plurality of polycationic segments, which can be joined by various other polymeric segments such as silicones and/or hydrophilic polymeric segments. The copolymer can be formulated as a highly-branched polymer, which can have substantivity to a fibrous material to impart oil repellency and/or water repellency. In several instances, the copolymer can be formulated to be fluorine-free. Various details of such copolymers are discussed, as well as methods of utilizing and making such copolymers.