Provided herein are disulfide polymers, methods of their preparation, compositions, and methods of using the same. For example, provided herein are polymers having at least one repeating unit according to Formula (I):or Formula (II): and nanoparticles and compositions including the same. The polymers and compositions provided herein may be used, for example, in the encapsulation of drugs for a slow release drug administration in the treatment or imaging of diseases.
