A simple procedure to tailor the compositional gradient of copolymeric materials

Copolymeric structures with compositional gradient were produced by "in situ" radical polymerization -in water and with redox initiation- of acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) in the presence of an inhibitor (hydroquinone). The inhibitor has a key role in controlling the mixing of precursor solutions because it produces a retardation of the polymerization. Raman spectral analysis confirmed the changes in the composition along the long axis of the produced cylindrical materials. Compression tests were also performed, exhibiting the gradient and reference material's unique properties, which were well correlated to the compositional pattern.