Fabrication and Photopatterning of Graded Polymer Coatings via Initiated Chemical Vapor Deposition

Polymer coatings with spatially graded properties are highly desirable for advanced applications in microfluidics, biomedical interfaces, and responsive materials yet remain challenging to fabricate with precision and scalability. Here, we report a solvent-free strategy for fabricating graded polymer coatings via initiated chemical vapor deposition (iCVD), combined with postdeposition photopatterning. A copolymer of N,N-dimethylacrylamide (DMAA) and allyl methacrylate (AMA) was deposited by dynamically adjusting monomer flow rates during iCVD, yielding coatings with a continuous vertical gradient in composition. Fourier transform infrared spectroscopy and energy-dispersive X-ray analysis confirmed a systematic variation in chemical composition throughout the coating thickness. Surface wettability evolved correspondingly, as evidenced by the water contact angle measurements. UV light (λ = 254 nm) exposure through photomask enabled spatial cross-linking of the allyl-containing regions, producing high-resolution micropatterns with approximately 380 nm etch depths in 90 min. Nanoindentation measurements revealed a gradient in mechanical stiffness, with Young’s modulus increasing from the DMAA-rich base (∼0.27 GPa) to the cross-linked AMA-rich surface (∼6.2 GPa) after UV irradiation. This approach demonstrates that temporal vapor-phase control and postfunctionalization can be synergistically integrated to fabricate conformal, mechanically anisotropic coatings with microstructured features. The strategy offers a versatile platform for engineering multifunctional polymer interfaces with precise spatial control, all within a dry, scalable, and lithography-compatible process.