Self-immolative polymers and compositions comprising such polymers are described. The polymers are copolymers of phthalaldehyde and one or more additional aldehydes and can degrade/decompose upon exposure to a desired stimulus, like light, heat, sound, or chemical trigger. The copolymers can be linear or cyclic, and can be crosslinked or uncrosslinked. Polymer compositions, including multilayered and multiregioned compositions, containing the copolymers are disclosed. These compositions can contain agents such as crosslinking agents, crosslinking catalysts, photocatalysts, thermocatalyst, sensitizers, chemical amplifiers, freezing point depressing agent, photo-response delaying agents, and the like. Methods of making and using the copolymers are also described.