A method for making multi-layer gradient composition thin films, the method comprising: introducing at least one chemical precursor into a plasma, wherein the introducing comprises introducing a first chemical precursor and at least a second chemical precursor different from the first chemical precursor; depositing a thickness of a first film to a surface of a substrate, the first film having a chemical composition derived from the at least one chemical precursor; modifying at least one plasma-related process parameter related to the deposition of the at least one chemical precursor during the depositing of a thickness of a first film; varying the chemical composition of at least a portion of the thickness of the first film, independently or in combination, in a vertical direction or in a vertical and horizontal direction relative to the substrate; depositing, within the first film, a thickness of a second film derived at least in part from the second chemical precursor, the second film of a chemical composition different from the first film, at least a portion of the second film is spatially separated in a horizontal direction, in a vertical direction, or in a horizontal and a vertical direction from the first film relative to the substrate; and providing an interface between the first film and the second film, the interface comprising a change in elemental composition of the first film relative to that of the second film, wherein the interface is between a vertical section of the first film and a vertical section of the second film relative to the substrate; wherein the first film and the second film each have a gradient chemical composition; wherein the deposition comprises an atmospheric plasma deposition technique; and wherein the first chemical precursor and the second chemical precursor are each selected from: (i) a cyclic siloxane; or (ii) tetramethylcyclocyclotetrasiloxane (TMCTS), octamethylcyclocyclotetrasiloxane (OMCTS), dimethyl siloxane (DMSO) or hexamethyldisiloxane (HMDSO). introducing at least one chemical precursor into a plasma, wherein the introducing comprises introducing a first chemical precursor and at least a second chemical precursor different from the first chemical precursor; depositing a thickness of a first film to a surface of a substrate, the first film having a chemical composition derived from the at least one chemical precursor; modifying at least one plasma-related process parameter related to the deposition of the at least one chemical precursor during the depositing of a thickness of a first film; varying the chemical composition of at least a portion of the thickness of the first film, independently or in combination, in a vertical direction or in a vertical and horizontal direction relative to the substrate; depositing, within the first film, a thickness of a second film derived at least in part from the second chemical precursor, the second film of a chemical composition different from the first film, at least a portion of the second film is spatially separated in a horizontal direction, in a vertical direction, or in a horizontal and a vertical direction from the first film relative to the substrate; and providing an interface between the first film and the second film, the interface comprising a change in elemental composition of the first film relative to that of the second film, wherein the interface is between a vertical section of the first film and a vertical section of the second film relative to the substrate; wherein the first film and the second film each have a gradient chemical composition; wherein the deposition comprises an atmospheric plasma deposition technique; and wherein the first chemical precursor and the second chemical precursor are each selected from: (i) a cyclic siloxane; or (ii) tetramethylcyclocyclotetrasiloxane (TMCTS), octamethylcyclocyclotetrasiloxane (OMCTS), dimethyl siloxane (DMSO) or hexamethyldisiloxane (HMDSO). (i) a cyclic siloxane; or (ii) tetramethylcyclocyclotetrasiloxane (TMCTS), octamethylcyclocyclotetrasiloxane (OMCTS), dimethyl siloxane (DMSO) or hexamethyldisiloxane (HMDSO).