We herein report a simple approach to the preparation of gas-forming polyacrylonitrile/polymethyl-methacrylate/methylcyclohexane core-shell nanocapsules for the desorption of optical adhesive films. The proposed gas-forming core-shell nanocapsules are based on a shell structure composed of a polyacrylonitrile/polymethylmethacrylate copolymer, where the core contains vaporizable cyclic hydrocarbons (i.e., methylcyclohexane). These stable functional nanocapsules were spherical in shape, with an average particle size of ~110 nm. Interestingly, using the proposed synthetic method, it was also possible to prepare nanoparticles with varying particle sizes and copolymer ratios through a simple pre-emulsification stage and careful control of the monomer ratio employed. Upon mixing the resulting core-shell nanocapsules uniformly with the optical adhesive films, desorption was observed between layers following heat treatment. Furthermore, the high optical transmittance of the optical adhesive film was retained due to the small size of the core-shell nanoparticles. It was therefore apparent that the proposed method should be applicable for the preparation of future optical films where functional core-shell nanocapsules are required.