All AR coatings deposited on polymer lenses except Chemalux AR in the market are made of brittle ceramic materials such as SiO2, ZrO2, TiO2. These two materials belong to two families with different behaviors. Polymer materials expand and contract 10 to 100 times more than ceramic materials. When these two materials bond together like AR coatings and exposed to heat, polymer lenses try to expand 100 unit length while AR coatings only expand 1 unit length. This will generate a bending over AR coatings, causing AR coatings crazing (see the illustration in the left).

Chemalux AR coatings use hybrid materials made of nanosize ceramic particles embedded into polymer matrix, similarly to scratch resisting coatings. Therefore, the thermal expansion is about same as the polymer lens. When Chemalux AR coated lens is subjected to heat, there is no thermal expansion mismatch, i.e. the Chemalux AR coatings expand the same amount as the lenses. Actually, Chemalux AR coatings are cured at about 100oC for more than one hour. So, the Chemalux AR coated lenses never crack, craze when exposured to the heat.