• Coatings;
  • Gradients;
  • Polymers;
  • Surface engineering;
  • Transport modeling

A new method for generating and modeling reduced-scale copolymer gradients by CVD is reported. By exploiting diffusion through confined channels, functionalized [2.2]paracyclophanes are copolymerized into their poly(p-xylylene) (PPX) analogues as a composition gradient. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) are used to verify the gradient composition profiles. Gradients are deposited on both flat substrates and 3-dimensional cylinders. Both the thickness and compositional profiles are fitted to a diffusion-based model using realistic physical parameters. The derived equation can be generalized and optimized for any copolymerization gradient through a confined geometry, thus allowing for broad applicability to other copolymer systems.