Objective Cyclic olefin copolymer (COC) is a kind of amorphous polymer material which attracts more and more attention in recent years, and it has many advantages such as high transmittance covering the full spectrum, low birefringence coefficient, very low water absorption, low density, not fragile, high Abbe number, stable chemical properties, acid and alkali resistance, and excellent mechanical properties. Compared with traditional transparent plastics such as polymethyl methacrylate (PMMA) and polycarbonate (PC), COC not only has the same optical performance as PMMA, but also has higher temperature resistance than it. And these characteristics are the excellent properties needed for the preparation of optical elements. Therefore, COC is considered as an ideal substitute material for PC, PMMA, polystyrene, polyvinyl chloride, and some engineering plastics, and has a good development prospect in the optical field. However, COC is similar to traditional polymer materials due to its high coefficient of thermal expansion, and thus film cracking or shedding occurs due to the temperature change during or after film coating. There are many domestic and foreign researches on the deposition of optical films on the surface of PC and PMMA, but there are few reports on the use of COC as the substrate, although COC has good performances in the visible band. Therefore, this paper mainly designs and develops the anti-reflection film for the band of 400--700 nm, and conducts researches on how to improve the adhesion and environmental resistance of optical films on the COC surface.

Methods The material characteristics are analyzed according to the thin film thermal stress theory, and the ZrO₂ with the smallest thermal stress is selected as the adhesive layer by calculating the thermal stress between the first layer material and the substrate. The plasma treatment time of the substrate surface is studied. The XPS test is performed on the surface of the treated sample to find a solution with a relatively high surface oxygen content, and the technological parameters are optimized to solve the problem of film shedding due to the mismatch between the coefficients of thermal expansion of the film and the substrate. It is found that the film layer of the sample after the film pulling test is not completely fell off. Firstly, the shedding position from the spectral curve of the sample is analyzed, and then through the analysis of the moment of film, the transition layer is coated, which improves the adhesion between the coating and the adhesive layer. Finally, the samples with the two structures are tested by SEM. Through the analysis of the micrograph of the film cracking sample after the constant temperature and humidity test, it is found that the film layer is not compact enough, which causes the water vapor to enter the film layer during the test and to change the stress, and the technology of ion beam bombardment after coating is used to increase the film filling density.

Results and Discussions The effect of plasma treatment under different time on the content of chemical elements and functional groups on the surface of the substrate is studied (Fig. 4), and the technological parameters are optimized to increase the activity of substrate surface and improve the adhesion between the substrate and the coating. The thermal stresses of different materials with COC as the substrate are analyzed (Table 2), and the ZrO₂ with the smallest thermal stress is selected as the adhesive layer, which solves the problem of film shedding due to the mismatch between the coefficients of thermal expansion of the film and the substrate. The film layer of the shedding sample is analyzed by the moment of film, and the adhesive layer L5 is coated in the middle, so that the film layers can infiltrate and form chemical bonds on the basis of moment matching (Fig. 7), which greatly improves the adhesion between the film layers. The technology of ion beam bombardment after coating solves the problem of low film aggregation density caused by non-heating in the film formation process (Table 6), and makes the sample pass the constant temperature and humidity test.

Conclusions In this paper, the cyclic olefin copolymer is used as the substrate to study the properties of the substrate and the film material. And ZrO₂ is selected as the adhesive layer and the surface of the substrate is treated with plasma to improve the adhesion between the film and the substrate. Then the moment between the film layers is analyzed and the L5 is selected as the transition layer material to combine the adhesive layer with the coating, so that the film layers can infiltrate and form chemical bonds on the basis of moment matching, which greatly improves the adhesion between the film layers. The technology of ion beam bombardment after coating solves the problem of film cracking in the constant temperature and humidity test due to the non-compact film layer. The test results show that the average reflectivity of the anti-reflection film at 400--700 nm is 0.117%. Furthermore, the anti-reflection film can pass the film adhesion test, the high and low temperature test, and the constant temperature and humidity test, and possesses good environmental adaptability.