Packaging materials including at least one copolymer sheet containing a first polymer having a high coefficient of thermal expansion, and a second polymer having a low coefficient of thermal expansion are described. In some configurations, the copolymer sheet includes one or more sections of a bimorph structure having a first layer of the first polymer and a second layer of the second polymer. Methods of making a packaging material by bonding the first layer and the second layer to form a copolymer sheet; and heating the copolymer sheet at discrete sections to destroy the layer definition forming discrete sections having a bimorph structure of the first layer and the second layer are also described, as are kits useful for preparing the packaging material.